• Scenario:
  • A 27-year-old transgender man presents to the clinic for a routine gynecological exam. He has not had a pelvic exam in over five years due to feelings of severe discomfort and body dysmorphia related to his reproductive organs. He expresses extreme anxiety about the visit because he fears being misgendered or treated insensitively by the healthcare staff or patients, which has happened to him in the past. 
  • This scenario requires cultural awareness and humility because it involves gender-affirming care, sensitive handling of body dysmorphia during a gynecological visit, and trauma-informed care.
• Cultural Factors to Consider:
  • Transgender identity:
    • The patient’s gender identity and pronouns must be respected throughout the entire interaction. Furthermore, he may have added psychological distress secondary to his identity during the encounter.
  • Body dysmorphia/Discomfort with reproductive anatomy:
    • The patient may experience body dysmorphia that results in discomfort with examinations that require exposure of his body. Dysmorphia surrounding reproductive organs can make gynecological exams especially emotionally and mentally taxing for transgender patients.
  • Past medical trauma:
    • The patient avoided gynecological care in the past due to prior negative experiences, such as being misgendered or mistreated by healthcare providers. He may have a mistrust in clinicians that requires more intentional efforts to build rapport. 
• Unique Beliefs or Considerations:
  • Avoiding gendered language in gynecological care:
    • Gender-neutral language should be used at all times to respect the patient’s gender identity and reduce distress. Gynecological care is not only for women.
  • Anxiety around vulnerable exams:
    • The patient experiences discomfort with his anatomy, which has led to avoidance of healthcare services that focus on these areas. Special sensitivity is needed to minimize emotional distress during the exam.
    • The patient may be particularly anxious about being undressed or exposed during the exam, especially the parts of his body that trigger dysphoria.
  • Impact of HRT:
    • If the patient is on testosterone, it may have caused changes to his reproductive organs that should be discussed. 
  • Fear of misgendering:
    • The patient’s past healthcare experiences might make him hypervigilant to any signs of being misgendered, increasing his anxiety during the visit. It may be best to limit the number of personnel that the patient has to interact with, in order to minimize his anxieties. 
• Areas of Potential Conflict
  • Body dysphoria and exposure:
    • The patient may feel overwhelmed or upset by the exam, particularly during the physical exposure of his genitalia. This can cause tension between the need for medical care and the patient’s emotional comfort.
  • Misgendering:
    • If the provider or staff use incorrect pronouns or language, this could lead to significant distress or trigger dysphoria, making the patient feel invalidated. He could even choose to leave the clinic without receiving care.
  • Gendered medical spaces:
    • The patient may feel uncomfortable in a health clinic environment that is often perceived as exclusively for women, potentially leading to feelings of isolation or unease. 
• Expected Skills to Be Demonstrated:
  • LGBTQ+ allyship
    • The student should acknowledge, but also normalize, the patient’s identity. It would be best for the student to share their own pronouns, and confirm the patient’s.
  • Cultural humility:
    • The student should be sensitive to the patient’s anxieties and acknowledge the emotional challenges associated with gynecological care as a transgender man.  However, the student shouldn’t say things about how they “understand” the patient’s anxieties, especially if the student is cisgender. The patient’s anxieties are unique to him and couldn’t be understood by the student.
  • Gender-affirming language:
    • Use gender-neutral or patient-preferred terms for body parts. Ask the patient what terms he is most comfortable with to describe his body.
  • Empathy and reassurance:
    • The clinician should regularly check in with the patient during the visit, ensuring his comfort and emotional well-being throughout the exam. 
  • Trauma-informed care:
    • Approach the exam with patience and an understanding of how body dysmorphia can cause heightened emotional responses. Offer options like having the patient keep his clothes on until absolutely necessary and maximizing coverage during the exam.
  • Clear communication:
    • Explain each step of the exam before proceeding, and provide options like a smaller speculum or alternative examination positions to minimize discomfort.
• Patient Education/Counseling/Follow-Up:
  • Education:
    • Discuss the importance of regular gynecological care and routine cervical cancer screening, even for transgender men.
    • Provide education on any health concerns specific to someone on testosterone, such as atrophy, amenorrhea, or changes in vaginal tissue. 
  • Counseling:
    • Offer a referral to a mental health professional experienced in transgender care and body dysmorphia.
    • Offer a referral to medical facilities or other community resources that specialize in providing care to LGBTQ+ patient populations.
  • Follow-up:
    • For routine care, the patient should ideally follow-up annually, but at most every three years for cervical cancer screening. He can follow-up as needed for any episodic complaints.
    • Ensure the patient knows he can request another provider if it helps him feel more comfortable and offer a follow-up visit where he can express any concerns about the care he received.
    • Emphasize that his emotional comfort is a priority and that future visits can be adjusted to his needs.

I plan to begin seriously studying for my PANCE in December, but I have been making preparations to streamline that for some time now and have been doing a lot of “passive” PANCE studying by studying for my EORs and OSCEs. I have been keeping track of my weak areas with this amazing tool that I found on Reddit, I seriously recommend it to everyone – Here’s the link, and I also posted it in our Class Drive  – I’ve been copying and pasting all my EOR missed keywords from my PAEA assessment hub, and it automatically organizes them by body system and question category, also generating me a review to-do list. From this, I have a clear idea of what I need to review by seeing what I have repeatedly gotten wrong over the course of this year.

Apparently ob-gyn and ortho/rheum are my weakest areas overall, so I plan to endeavor on extra practice questions on those categories. I also can see what specific diseases I have gotten questions wrong repeatedly, and I plan to review those topics in depth. For example, Multiple Sclerosis and Myasthenia Gravis seem to trip me up over and over, so they will both get extra attention. Clinical therapeutics and interventions seem to be my weakest question type, so I will also pay special attention to review those as I study. I compared my spreadsheet to my EOC performance and my weak areas seem to be fairly consistent across both, which is helpful to verify.
 
In terms of resources, I strategically have used only Rosh over the course of this year so that I could save Kaplan and UWorld to use for my PANCE-specific studying. I plan to do as many practice questions as I can, doing extra of the aforementioned categories and question types. Regarding the specific diseases that I seem to constantly struggle with, I will use Osmosis and my old ClinMed notes. I am a visual learner, so Osmosis really helps me to retain information that I otherwise find difficult to grasp. PANCE Prep Pearls is also perfect for this area of my studying, so I definitely will use it to review these problem topics as well.

Regarding timing, I plan to dedicate our week off December 9th-15th to studying as much as I can and then attend our on-campus review the following week. I want to slow my studying to give my brain a break between December 20th and 25th, celebrating graduation and Christmas. Then on December 26th, I will take a full-length practice test to see how I do, and then reassess my remaining weak areas and study them daily through New Year’s Eve. From there, I hope to feel prepared enough that I can take the days leading up to my exam day to rest, as I have found that to be best for my focus on exam day. While having a general study plan is important, I don’t want to make too detailed of a plan. I know by now that my ability to focus varies unpredictably on a daily basis. I have found that I perform better and feel better when I honor that part of myself, so I want to approach my study schedule with flexibility in which topics I cover each day — But I am confident I will get everything done because I always do! 

Clinical Question: 
A 4YOM diagnosed with otitis media is prescribed amoxicillin. His mother is concerned because she says the last time he took amoxicillin for an ear infection, he developed diarrhea for multiple days. She said she researched the subject and read that supplementary probiotics could be helpful in preventing this adverse effect, and she asked if I recommend she gives them to him.

PICO Question: 
In children prescribed antibiotics, does probiotic supplementation reduce the incidence of antibiotic-associated diarrhea?

P: children taking antibiotics, Pediatric patients taking antibiotics
I: Probiotic supplementation, Probiotic use
C: No probiotics, Placebo
O: Incidence of antibiotic-associated diarrhea (AAD), Prevention of antibiotic-associated diarrhea (AAD)

Search Strategy: 
In searching for my articles, my strategy had a few different components. First, I limited my search results to be for articles from the past 10 years. Furthermore, given the number of high level articles I was seeing, I wanted to ensure that my chosen articles were highest level, so I began my searches by adding “systematic review” as either a keyword or a search filter – Not only because they provide the highest level of evidence, but also because I know that my search question is fairly broad and rigorously researched, so I expected reviews to be plentiful. From there, I browsed abstracts and chose articles most specific to my PICO question, sometimes going back to remove the “systematic review” keyword in order to broaden my results.

1. CUNY York OneSearch
probiotic antibiotic diarrhea children systematic review → 2014-2024 → 68 results 
I scrolled through the first 10 results. I prioritized peer-reviewed level 1 evidence studies with open access. I looked for articles from American journals. I looked for titles that best matched my PICO keywords. 
The Fadin et al. article was the 1st result.
The Guo et al. article was the 5th result.

2. NIH PMC 
probiotic antibiotic diarrhea children systematic review → 2014 – 2024 → 33 results
I scrolled through the first 10 results. I looked for articles from American journals. I looked for titles that best matched my PICO keyword.
The Szajewska et al. review was the 1st result 
The Yang et al. review was the 8th result

3. Google Scholar
Being familiar with it, I know the Google Scholar algorithm tends to generate many more results than other search engines do. I opted to include more keywords in my search than I did on the other search engines, in hopes of making my results more selective and applicable to my PICO.
probiotic antibiotic diarrhea children pediatrics systematic review → 2014-2024 → 16,200 results
I opened and appraised an article, but I realized it was a narrative review that was not very applicable.
The Hayes et al. review was the 5th result.
I scrolled through the first page of results but was only seeing the articles I had already selected, as well as earlier versions of the same studies – I decided to return to PubMed for my 6th article.

4. NIH PMC
pediatric antibiotic induced diarrhea probiotics → newest first
Given that I was seeing so many of the same studies repeatedly, I wanted to look with the filter of “newest first” to mix up the first generated page of results. This also ensures I include the most recent data. I removed “review” or “systematic review” to broaden my results.
The Lukasik et al. study was the 6th result.

Articles Chosen for Inclusion:

Article 1: Probiotics in the Management of Antibiotic-Associated Diarrhea in Children

Citation
Fadin L, Vieira K, Toledo A, da Silva A, Pereira V, Winkelstroter L. Probiotics in the Management of Antibiotic-Associated Diarrhea in Children. Topics in Clinical Nutrition. 2023; 38 (3): 211-223. doi: 10.1097/TIN.0000000000000332.

Abstract
This review aimed to evaluate probiotic use to prevent antibiotic-associated diarrhea in children. A total of 1564 studies of randomized clinical trials published in English were found using PubMed, Cochrane, and Virtual Health Library (MEDLINE/LILACS). A meta-analysis included 4 trials in subgroup Lactobacillus rhamnosus (95% confidence interval [CI]: 0.17-0.49; P < .00001), 2 trials in subgroup L reuteri (95% CI: 0.51-1.77; P = .87), and 5 groups in subgroup association of species of probiotics (95% CI: 0.21-1.71; P = .33). The findings suggest that L rhamnosus alone may be useful in preventing antibiotic-associated diarrhea in children.

Article 2: Probiotics for the prevention of pediatric antibiotic‐associated diarrhea

Citation
Guo Q, Goldenberg JZ, Humphrey C, El Dib R, Johnston BC. Probiotics for the prevention of pediatric antibiotic-associated diarrhea. Cochrane Database Syst Rev. 2019;4(4):CD004827. Published 2019 Apr 30. doi:10.1002/14651858.CD004827.pub5

Abstract
Background
Antibiotics alter the microbial balance commonly resulting in antibiotic‐associated diarrhea (AAD). Probiotics may prevent AAD via providing gut barrier, restoration of the gut microflora, and other potential mechanisms of action.

Objectives
The primary objectives were to assess the efficacy and safety of probiotics (any specified strain or dose) used for the prevention of AAD in children.

Search methods
MEDLINE, Embase, CENTRAL, CINAHL, and the Web of Science (inception to 28 May 2018) were searched along with registers including the ISRCTN and Clinicaltrials.gov. We also searched the NICE Evidence Services database as well as reference lists from relevant articles.

Selection criteria
Randomized, parallel, controlled trials in children (0 to 18 years) receiving antibiotics, that compare probiotics to placebo, active alternative prophylaxis, or no treatment and measure the incidence of diarrhea secondary to antibiotic use were considered for inclusion.

Data collection and analysis
Study selection, data extraction, and risk of bias assessment were conducted independently by two authors. Dichotomous data (incidence of AAD, adverse events) were combined using a pooled risk ratio (RR) or risk difference (RD), and continuous data (mean duration of diarrhea) as mean difference (MD), along with corresponding 95% confidence interval (95% CI). We calculated the number needed to treat for an additional beneficial outcome (NNTB) where appropriate. For studies reporting on microbiome characteristics using heterogeneous outcomes, we describe the results narratively. The certainty of the evidence was evaluated using GRADE.

Main results
Thirty‐three studies (6352 participants) were included. Probiotics assessed included Bacillus spp., Bifidobacterium spp., Clostridium butyricum , Lactobacilli spp. , Lactococcus spp., Leuconostoc cremoris , Saccharomyces spp., orStreptococcus spp., alone or in combination. The risk of bias was determined to be high in 20 studies and low in 13 studies. Complete case (patients who did not complete the studies were not included in the analysis) results from 33 trials reporting on the incidence of diarrhea show a precise benefit from probiotics compared to active, placebo or no treatment control.

After 5 days to 12 weeks of follow‐up, the incidence of AAD in the probiotic group was 8% (259/3232) compared to 19% (598/3120) in the control group (RR 0.45, 95% CI 0.36 to 0.56; I² = 57%, 6352 participants; NNTB 9, 95% CI 7 to 13; moderate certainty evidence). Nineteen studies had loss to follow‐up ranging from 1% to 46%. After making assumptions for those lost, the observed benefit was still statistically significant using an extreme plausible intention‐to‐treat (ITT) analysis, wherein the incidence of AAD in the probiotic group was 12% (436/3551) compared to 19% (664/3468) in the control group (7019 participants; RR 0.61; 95% CI 0.49 to 0.77; P <0.00001; I² = 70%). An a priori available case subgroup analysis exploring heterogeneity indicated that high dose (≥ 5 billion CFUs per day) is more effective than low probiotic dose (< 5 billion CFUs per day), interaction P value = 0.01. For the high dose studies the incidence of AAD in the probiotic group was 8% (162/2029) compared to 23% (462/2009) in the control group (4038 participants; RR 0.37; 95% CI 0.30 to 0.46; P = 0.06; moderate certainty evidence). For the low dose studies the incidence of AAD in the probiotic group was 8% (97/1155) compared to 13% (133/1059) in the control group (2214 participants; RR 0.68; 95% CI 0.46 to 1.01; P = 0.02). Again, assumptions for loss to follow‐up using an extreme plausible ITT analysis was statistically significant. For high dose studies the incidence of AAD in the probiotic group was 13% (278/2218) compared to 23% (503/2207) in control group (4425 participants; RR 0.54; 95% CI 0.42 to 0.70; P <0.00001; I² = 68%; moderate certainty evidence).

None of the 24 trials (4415 participants) that reported on adverse events reported any serious adverse events attributable to probiotics. Adverse event rates were low. After 5 days to 4 weeks follow‐up, 4% (86/2229) of probiotics participants had an adverse event compared to 6% (121/2186) of control participants (RD 0.00; 95% CI ‐0.01 to 0.01; P < 0.00001; I² = 75%; low certainty evidence). Common adverse events included rash, nausea, gas, flatulence, abdominal bloating, and constipation.

After 10 days to 12 weeks of follow‐up, eight studies recorded data on our secondary outcome, the mean duration of diarrhea; with probiotics reducing diarrhea duration by almost one day (MD ‐0.91; 95% CI ‐1.38 to ‐0.44; P <0.00001; low certainty evidence). One study reported on microbiome characteristics, reporting no difference in changes with concurrent antibiotic and probiotic use.

Authors’ conclusions
The overall evidence suggests a moderate protective effect of probiotics for preventing AAD (NNTB 9, 95% CI 7 to 13). Using five criteria to evaluate the credibility of the subgroup analysis on probiotic dose, the results indicate the subgroup effect based on high dose probiotics (≥ 5 billion CFUs per day) was credible. Based on high‐dose probiotics, the NNTB to prevent one case of diarrhea is 6 (95% CI 5 to 9). The overall certainty of the evidence for the primary endpoint, incidence of AAD, based on high dose probiotics was moderate due to the minor issues with risk of bias and inconsistency related to a diversity of probiotic agents used. Evidence also suggests that probiotics may moderately reduce the duration of diarrhea, a reduction by almost one day. The benefit of high dose probiotics (e.g. Lactobacillus rhamnosus orSaccharomyces boulardii) needs to be confirmed by a large well‐designed multi‐centered randomized trial. It is premature to draw firm conclusions about the efficacy and safety of ‘other’ probiotic agents as an adjunct to antibiotics in children. Adverse event rates were low and no serious adverse events were attributable to probiotics. Although no serious adverse events were observed among inpatient and outpatient children, including small studies conducted in the intensive care unit and in the neonatal unit, observational studies not included in this review have reported serious adverse events in severely debilitated or immuno‐compromised children with underlying risk factors including central venous catheter use and disorders associated with bacterial/fungal translocation.

Article 3: Overview of systematic reviews of probiotics in the prevention and treatment of antibiotic-associated diarrhea in children

Citation
Yang Q, Hu Z, Lei Y, et al. Overview of systematic reviews of probiotics in the prevention and treatment of antibiotic-associated diarrhea in children. Front Pharmacol. 2023;14:1153070. Published 2023 Jul 24. doi:10.3389/fphar.2023.1153070

Abstract
Background: Antibiotics alter the microbial balance commonly resulting in antibiotic-associated diarrhea (AAD). Probiotics may prevent and treat AAD by providing the gut barrier and restoring the gut microflora. This study will overview the Systematic Reviews (SRs) of probiotics in preventing and treating AAD in children. It will also assess the reporting, methodological, and evidence quality of the included SRs to provide evidence for their clinical practice. Methods: After searching PubMed, Embase, Cochrane Library, CNKI, CBM, VIP, and WanFang Data databases, and finally included SRs of probiotics in the prevention and treatment of AAD in children, which were published before 1 October 2022. The reporting, methodological, and evidence quality of the included SRs were assessed by PRISMA 2020 statement, AMSTAR 2 tool, and GRADE system. Results: A total of 20 SRs were included, and the results of PRISMA 2020 showed that 4 out of 20 SRs with relatively complete reporting, and the others within some reporting deficiencies, with scores ranging from 17 points to 26.5 points; the results of AMSTAR 2 showed that 3 SRs belonged to moderate quality level, 10 SRs belonged to low-quality level and 7 SRs being extremely low-quality level; the results of the GRADE system showed that a total of 47 outcomes were reported for the included SRs, three were high-level evidence quality, 16 were medium-level evidence quality, 24 were low-level evidence quality, and four were extremely low-level evidence quality; the results of the Meta-analysis showed that high doses (5-40 billion CFUs per day) of probiotics had a significant effect in the prevention of AAD, but it is too early to conclude the effectiveness and safety of other probiotic drugs for AAD in children, except for Lacticaseibacillus rhamnosus and Saccharomyces boulardii. Conclusion: Current evidence shows that probiotics effectively prevent and treat AAD in children, and the effect of probiotics on pediatric AAD may be a potential dose-response effect. However, the conclusion should be treated with caution due to deficiencies in the methodological, reporting, and evidence quality of the included SRs. Therefore, the methodological, reporting, and evidence quality of relevant SRs still need further improvement.

Article 4: Probiotics for the Prevention of Antibiotic-Associated Diarrhea in Children

Citation
Szajewska H, Canani RB, Guarino A, et al. Probiotics for the Prevention of Antibiotic-Associated Diarrhea in Children. J Pediatr Gastroenterol Nutr. 2016;62(3):495-506. doi:10.1097/MPG.0000000000001081

Abstract
This article provides recommendations, developed by the Working Group (WG) on Probiotics of the European Society for Pediatric Gastroenterology, Hepatology, and Nutrition, for the use of probiotics for the prevention of antibiotic-associated diarrhea (AAD) in children based on a systematic review of previously completed systematic reviews and of randomized controlled trials published subsequently to these reviews. The use of probiotics for the treatment of AAD is not covered. The recommendations were formulated only if at least 2 randomized controlled trials that used a given probiotic (with strain specification) were available. The quality of evidence (QoE) was assessed using the Grading of Recommendations Assessment, Development, and Evaluation guidelines. If the use of probiotics for preventing AAD is considered because of the existence of risk factors such as class of antibiotic(s), duration of antibiotic treatment, age, need for hospitalization, comorbidities, or previous episodes of AAD diarrhea, the WG recommends using Lactobacillus rhamnosus GG (moderate QoE, strong recommendation) or Saccharomyces boulardii (moderate QoE, strong recommendation). If the use of probiotics for preventing Clostridium difficile-associated diarrhea is considered, the WG suggests using S boulardii (low QoE, conditional recommendation). Other strains or combinations of strains have been tested, but sufficient evidence is still lacking.

Article 5: Probiotics for the Prevention of Pediatric Antibiotic-Associated Diarrhea

Citation
Hayes SR, Vargas AJ. Probiotics for the Prevention of Pediatric Antibiotic-Associated Diarrhea. Explore (NY). 2016;12(6):463-466. doi:10.1016/j.explore.2016.08.015

Abstract
Background: Antibiotics are frequently prescribed in children. They alter the microbial balance within the gastrointestinal tract, commonly resulting in antibiotic-associated diarrhea (AAD). Probiotics may prevent AAD via restoration of the gut microflora.

Objectives: The primary objectives were to assess the efficacy and safety of probiotics (any specified strain or dose) used for the prevention of AAD in children.

Search methods: MEDLINE, EMBASE, CENTRAL, CINAHL, AMED, and the Web of Science (inception to November 2014) were searched along with specialized registers including the Cochrane IBD/FBD review group, CISCOM (Centralized Information Service for Complementary Medicine), NHS Evidence, the International Bibliographic Information on Dietary Supplements, as well as trial registries. Letters were sent to authors of included trials, nutraceutical and pharmaceutical companies, and experts in the field requesting additional information on ongoing or unpublished trials. Conference proceedings, dissertation abstracts, and reference lists from included and relevant articles were also searched.

Selection criteria: Randomized, parallel, controlled trials in children (0-18 years) receiving antibiotics, that compare probiotics to placebo, active alternative prophylaxis, or no treatment and measure the incidence of diarrhea secondary to antibiotic use were considered for inclusion.

Data collection and analysis: Study selection, data extraction, and methodological quality assessment using the risk of bias instrument were conducted independently and in duplicate by two authors. Dichotomous data (incidence of diarrhea and adverse events) were combined using a pooled risk ratio (RR) or risk difference (RD), and continuous data (mean duration of diarrhea and mean daily stool frequency) as mean difference (MD), along with their corresponding 95% confidence interval (95% CI). For overall pooled results on the incidence of diarrhea, sensitivity analyses included available case versus extreme-plausible analyses and random- versus fixed-effect models. To explore possible explanations for heterogeneity, a priori subgroup analysis was conducted on probiotic strain, dose, definition of antibiotic-associated diarrhea, and risk of bias. We also conducted post hoc subgroup analyses by patient diagnosis, single versus multi-strain, industry sponsorship, and inpatient status. The overall quality of the evidence supporting the outcomes was evaluated using the GRADE criteria.

Main results: Overall, 23 studies (3938 participants) met the inclusion criteria. Trials included treatment with either Bacillus spp., Bifidobacterium spp., Clostridium butyricum, Lactobacilli spp., Lactococcus spp., Leuconostoc cremoris, Saccharomyces spp., or Streptococcus spp., alone or in combination. Eleven studies used a single-strain probiotic, four combined two probiotic strains, three combined three probiotic strains, one combined four probiotic strains, two combined seven probiotic strains, one included ten probiotic strains, and one study included two probiotic arms that used three and two strains, respectively. The risk of bias was determined to be high or unclear in 13 studies and low in 10 studies. Available case (patients who did not complete the studies were not included in the analysis) results from 22/23 trials reporting on the incidence of diarrhea show a precise benefit from probiotics compared to active, placebo, or no treatment control. The incidence of AAD in the probiotic group was 8% (163/1992) compared to 19% (364/1906) in the control group (RR = 0.46; 95% CI: 0.35-0.61; I2 = 55%, 3898 participants). A GRADE analysis indicated that the overall quality of the evidence for this outcome was moderate. This benefit remained statistically significant in an extreme-plausible (60% of children lost to follow-up in probiotic group and 20% lost to follow-up in the control group had diarrhea) sensitivity analysis, where the incidence of AAD in the probiotic group was 14% (330/2294) compared to 19% (426/2235) in the control group (RR = 0.69; 95% CI: 0.54-0.89; I2 = 63%, 4529 participants). None of the 16 trials (n = 2455) that reported on adverse events documented any serious adverse events attributable to probiotics. Meta-analysis excluded all but an extremely small non-significant difference in adverse events between treatment and control (RD = 0.00, 95% CI: -0.01 to 0.01). The majority of adverse events were in placebo, standard care, or no treatment group. Adverse events reported in the studies include rash, nausea, gas, flatulence, abdominal bloating, abdominal pain, vomiting, increased phlegm, chest pain, constipation, taste disturbance, and low appetite. AUTHORS׳ CONCLUSIONS: Moderate quality evidence suggests a protective effect of probiotics in preventing AAD. Our pooled estimate suggests a precise (RR 0.46; 95% CI: 0.35-0.61) probiotic effect with an NNT of 10. Among the various probiotics evaluated, Lactobacillus rhamnosus or Saccharomyces boulardii at 5-40 billion colony-forming units/day may be appropriate given the modest NNT and the likelihood that adverse events are very rare. It is premature to draw conclusions about the efficacy and safety of other probiotic agents for pediatric AAD. Although no serious adverse events were observed among otherwise healthy children, serious adverse events have been observed in severely debilitated or immunocompromised children with underlying risk factors including central venous catheter use and disorders associated with bacterial/fungal translocation. Until further research has been conducted, probiotic use should be avoided in pediatric populations at risk for adverse events. Future trials would benefit from a standard and valid outcomes to measure AAD.

Article 6: Probiotics for the prevention of antibiotic-associated adverse events in children-A scoping review to inform development of a core outcome set

Citation
Łukasik J, Guo Q, Boulos L, Szajewska H, Johnston BC. Probiotics for the prevention of antibiotic-associated adverse events in children-A scoping review to inform development of a core outcome set. PLoS One. 2020;15(5):e0228824. Published 2020 May 29. doi:10.1371/journal.pone.0228824

Abstract
Introduction: Routine use of probiotics during antibiotic therapy in children remains a subject of discussion. To facilitate synthesis of individual study results and guideline formulation, it is important to assess predefined, similar, and clinically important outcomes. Core outcome sets are a proposed solution for this issue. The aim of this review was to document choice, design, and heterogeneity of outcomes in studies that assessed the effects of probiotics used for the prevention of antibiotic-associated adverse events in children.

Methods: A scoping literature search covering three major databases was performed. Studies that evaluated oral probiotics’ use concomitant with antibiotic therapy in children were included. Data on outcome definitions, measurement instruments, and follow-up were extracted. The outcomes were assigned to predefined core areas and domains. Data were analyzed descriptively.

Results: Thirty-seven studies were included in this review. Diarrhea, the most commonly reported outcome, had diagnostic criteria clearly defined only in 21 studies. In total, 16 different definitions of diarrhea were identified. Diarrhea duration, severity, and etiology were reported in 9, 4, and 7 studies, respectively. Twenty studies assessed gastrointestinal symptoms other than diarrhea. Seven studies reported outcomes related to resource use or the economic impact of the intervention. Only 2 studies assessed outcomes related to life impact. None of the studies predefined adverse events of probiotic use.

Conclusions: Identified outcomes were characterized by substantial heterogeneity. The majority of outcomes were not designed to evaluate endpoints of real-life relevance. Results from this review suggest the need for a new core outcome set consisting of outcomes important for decision-making.

——-

Summary of the Evidence:

Author (Date)	Level of Evidence	Sample/Setting(# of subjects/ studies, cohort definition etc. )	Outcome(s) studied	Key Findings	Limitations and Biases
Fadin et al. (2023)	Level I	Articles had to meet the following criteria: (i) studies evaluating the effectiveness of probiotic use in AAD; (ii) studies in children from 0 to 17 years of age; and (iii) studies using a randomized, placebo-controlled study design.  A total of 1564 records were identified. Of these, 40 records were selected by title and abstract and 12 full-text articles were included in the analysis. All included similar data including probiotic regimen (single or multistrain), daily dose administered, and the duration of probiotic treatment, in addition to the diagnosis that motivated the use of antibiotic treatment	1. incidence of AAD by the percentage extracted to demonstrate the effectiveness of using probiotics 2. duration of follow-up3. duration of days of diarrhea.	Majority of studies demonstrated that the probiotic group had a lower incidence of AAD in children, with the exception of 2. Both tested the organism L reuteri. Suggesting its low efficacy in reducing incidence of pediatric AAD. The most significant result was the reduction of the risk of AAD by approximately 95%, using the highest probiotic dose (2 × 10 10 CFU/2× daily) of L rhamnosus	Variations in methodological quality among the selected studies.  Different definitions of AAD or diarrhea, as well as the different units of measurement used to refer to the amount of probiotic applied and the time of administration.
Guo et al. (2019)	Level I	Randomized, parallel, controlled trials in children (0 to 18 years) receiving antibiotics, that compare probiotics to placebo, active alternative prophylaxis, or no treatment  Thirty‐three studies (6352 participants) were included.	Incidence of diarrhea secondary to antibiotic use  Secondary: Mean duration of diarrheaAdverse event rates	Overall evidence suggests a moderate protective effect of probiotics for preventing AAD (NNTB 9, 95% CI 7 to 13).  The subgroup effect based on high dose probiotics (≥ 5 billion CFUs per day) was most credible (NNTB 6 (95% CI 5 to 9). Evidence also suggests that probiotics may moderately reduce the duration of diarrhea, a reduction by almost one day.	Data from studies testing different probiotic species were pooled. The overall certainty of the evidence for the primary endpoint, incidence of AAD, based on high dose probiotics was moderate due to the issues with risk of bias and inconsistency related to a diversity of probiotic agents used.
Szajewska et al. (2016)	Level I	previously completed systematic reviews and of randomized controlled trials (RCTs) published through November 2015 21 RCTs involving 3255 children were included	Incidence of diarrhea/AAD and C difficile-associated diarrhea (all as defined by the investigators)	The pooled results of 21 RCTs showed that compared with placebo or no intervention, probiotics as a class reduced the risk of AAD by 52% (21.2% vs 9.1%, respectively; RR 0.48, 95% CI 0.37–0.61)  If the use of probiotics for preventing AAD is considered, they recommend using L rhamnosus GG or S boulardii (moderate quality of evidence; strong recommendation).	The quality of each SR included, and then also of each RCT included in each SR, varied widely. Many trials included unclear random sequence generation, unclear or no allocation concealment, and unclear or no blinding of participants and personnel. Methods and analyses performed also varied between included SRs.
Yang et al. (2022)	Level I	SRs of probiotics in the prevention and treatment of AAD in children, which were published before 1 October 2022 A total of 20 SRs were included	incidence of AAD; adverse effects; duration of diarrhea;  total effective rate;  mean hospital stay; incidence of CDAD; mean stool frequency; cure rate;  antidiarrheal time.	High doses (5–40 billion CFUs per day) of the probiotic organisms L.  rhamnosus and S. boulardii  had a significant effect in the prevention of AAD They also improve the overall efficiency and clinical cure rate, shorten the duration of diarrhea, mean frequency of diarrhea, the average hospitalization time and antidiarrheal time, and the incidence of adverse effects was low, the safety of probiotics was good.	The results of existing evidence show that the methodological, reporting and evidence quality of SRs of probiotics for AAD in children are generally low. There is still a need to improve the quality of evidence-based evidence to better explain the clinical application value of probiotics for AAD in children in the future. The results of this study need to be applied with reasonable interpretation.
Hayes and Vargas, (2016)	Level I	Randomized, parallel, controlled trials in children (0–18 years) receiving antibiotics, that compare probiotics to placebo, active alternative prophylaxis, or no treatment and measure the incidence of diarrhea secondary to antibiotic use were considered for inclusion. Overall, 23 studies (3938 participants) met the inclusion criteria.	incidence of AAD Adverse events attributable to probiotics	Moderate quality evidence suggests a protective effect of probiotics in preventing AAD. Pooled estimate suggests a probiotic effect with an NNT of 10. Among the various probiotics evaluated, Lactobacillus rhamnosus or Saccharomyces boulardii at 5–40 billion colony-forming units/day may be appropriate given the modest NNT and the likelihood that adverse events are very rare.	Heterogeneity and high risk of bias in some studies Variable definitions of diarrhea with respect to the frequency, duration, and consistency of bowel movements significantly modified the reported benefit of probiotic treatment on the risk of AAD.
Lukasik et al., 2020	Level I	Studies that evaluated oral probiotics’ use concomitant with antibiotic therapy in children were included. Eligible studies could be RCTs, non-randomized trials (NRTs), or observational studies (e.g., cohort studies, case-control studies) and had to be conducted in a population of children up to 18 years of age.  Thirty-seven studies were included in this review. 32 were RCTs.	Incidence of diarrhea was the most commonly reported outcome Diarrhea duration, severity, and etiology were reported in 9, 4, and 7 studies, respectively.	Outcomes reported in studies on probiotic use in children receiving antibiotic therapy are characterized by substantial heterogeneity. In the majority of trials, the outcomes and outcome measures are not designed to evaluate outcomes of real-life relevance such as patient and parent reported quality of life. Results from this review suggest the need for a new core outcome set with endpoints that cover the span of domains and outcomes important to patients, families and clinicians for decision-making.	Essentially, this large SR concluded that the studies they analyzed were far too heterogenous to even find helpful to be analyzed together. The discussion moreso lists out how every variable considered is limited by severe heterogeneity having to do with differences in definition of variables, clinical setting, adverse effects evaluated, and more. I thought this study was important to include because it has many of the same articles as the other studies, but was deemed invaluable.

Conclusion(s):

Fadin et al. (2023)	Studies testing the organism L reuteri did not find it to have a significant effect on reducing pediatric AAD, implying its low efficacy. All studies testing other organisms demonstrated that the probiotic group had a lower incidence of AAD. The most significant result was the reduction of the risk of AAD by approximately 95%, using the highest probiotic dose (2 × 10^10 CFU/2× daily) of L rhamnosus.
Guo et al. (2019)	Overall evidence suggests a moderate protective effect of probiotics for preventing AAD. The most significant effect was seen using high dose probiotics (≥ 5 billion CFUs per day). Evidence also suggests that probiotics may moderately reduce the duration of diarrhea, a reduction by almost one day.
Szajewska et al. (2016)	The pooled results of 21 RCTs showed that compared with placebo or no intervention, probiotics as a class reduced the risk of AAD by 52%. The microorganisms L rhamnosus GG or S boulardii demonstrated the most significant effect.
Yang et al. (2022)	High doses (5–40 billion CFUs per day) of the probiotic organisms L.  rhamnosus and S. boulardii  had a significant effect in the prevention of AAD. They also improve the overall efficiency and clinical cure rate, as well as shorten the duration of diarrhea, mean frequency of diarrhea, average hospitalization time and antidiarrheal time.
Hayes and Vargas (2016)	Moderate quality evidence suggests a protective effect of probiotics in preventing AAD, with an NNT of 10. Among the various probiotics evaluated, Lactobacillus rhamnosus or Saccharomyces boulardii at 5–40 billion colony-forming units/day seems most appropriate.
Lukasik et al. (2020)	This review is unable to come to clinically applicable conclusions, because outcomes reported in studies are characterized by substantial heterogeneity. In the majority of trials, the outcomes and outcome measures are not designed to evaluate outcomes of real-life relevance such as patient and parent reported quality of life. Results from this review suggest the need for a standardized outcome set with endpoints that cover topics that are important to patients, families and clinicians for decision-making.

Five of six appraised systematic reviews found an overall significant protective benefit of probiotic supplementation against antibiotic-associated diarrhea in children. Each of these five reviews concluded that this effect is dose-dependent, recommending high doses of 5 to 40 billion colony-forming units/day. These reviews also all concluded that the microorganism Lactobacillus rhamnosus had the most significant protective effect, with most also finding Saccharomyces boulardii to be of greater efficacy than other organisms. Dissimilarly, the final review that I appraised was unable to come to any conclusions regarding the efficacy of probiotics in preventing antibiotic-associated diarrhea in children. This is because the authors believe that the studies they analyzed, some of which have overlapping inclusion criteria with the other reviews that I appraised, were of low level evidence and have too much heterogeneity when it comes to the operationalization of variables and outcomes. Therefore, the authors state that their pooled analysis could not be used to confidently make clinical recommendations.

Clinical Bottom Line:

Weight of the Evidence
1. Guo et al. (2019)
This is a Cochrane Review with a large sample and rigorous selection process, updating and building on a Cochrane published a few years early, thus I weigh it highest.

2. Lukasik et al. (2020)
This study came out one year after the Guo et al. article and has similar aims, methods, and articles analyzed, making it an important comparator. However, keeping that in mind, this study concluded that too much heterogeneity existed between the articles to draw conclusions, which to me indicates that the researchers were extremely rigorous and responsible about their research. Thus, I weigh it second.

3. Fadin et al. (2023)
This is the newest study I found, but is relatively smaller compared to other articles I chose. I still weigh it highly given its recency, but find the methods and magnitude to be inferior to Guo et al.

4. Yang et al. (2022)
This is the second most recent study analyzed, and it’s a systematic review of systematic reviews. Although this makes it a more robust study, it also increases the likelihood of homogeneity between the SRs and the RCTs they individually contain, which is something I am wary of given the conclusions of Lukasik et al.

5. Hayes and Vargas (2016)
This is an older study, so I weigh it less heavily. Compared to the Szajewska study from 2016, this study only analyzes randomized, parallel, controlled trials, which likely will have less heterogeneity compared to the other study. Given the conclusions of Lukasik et al., I believe that means stronger evidence.

6. Szajewska et al. (2016)
As mentioned above, this is an older study that analyzes SRs, making it possibly outdated and also increasing the likelihood of heterogeneity amongst the studies analyzed. Thus, I weigh it the least.

Magnitude of any effects
Of the five reviews that reported effects, each reported moderate evidence of the protective effects of probiotics in general against pediatric antibiotic-associated diarrhea. The specific microorganisms L.  rhamnosus or S.boulardii at 5–40 billion colony-forming units/day were consistently shown to have a strong level of evidence demonstrating its protective effect. Unfortunately, the range of doses, frequency, and duration were too heterogeneous between each article and their analyzed studies to draw conclusions on such parameters.

Clinical significance
To answer my patient’s mother’s question, I would tell her it seems worthwhile to pursue probiotic supplementation over the course of her child’s amoxicillin course, and that I specifically recommend daily probiotic supplementation of greater than 5 billion CFU of L. rhamnosus. This specific microorganism and dose consistently shows a strong protective benefit against antibiotic-associated diarrhea, without significant additional adverse effects. Specifically, high-dose L. rhamnosus seems to prevent antibiotic-associated diarrhea from occurring at all in some patients. In others, it seems to decrease the duration of diarrheal symptoms when they do occur. It seems to completely prevent diarrheal symptoms in anywhere between 1-in-6 to 1-in-10 patients, depending on the study. It seems to decrease symptom duration by at least 1 day according to multiple studies.
I would caution this mother that this practice requires further research to be more precise, but generally, the benefits demonstrated are significant and far outweigh any risks. Given heterogeneity between studies, more research is required to establish which treatment schedule is most ideal, but many studies researched coadministration on the same days that antibiotics are given, so I would be comfortable advising that.

Other considerations
It’s important to keep in mind what Lukasik et al. concluded in 2020, which is that the existing body of research was too heterogenous for a pooled analysis. It’s evident that more research is required to formally guide clinical practice. All of the appraised reviews, including the ones who made recommendations for high-dose L. rhamnosus supplementation, acknowledged issues with heterogeneity and low-level evidence in their included studies. They still felt data was adequate to draw conclusions, and while I agree that the data supports high-dose L. rhamnosus supplementation despite these study limitations, it’s clear that higher level research needs to be completed in order to better validate these findings. Specifically, standardizing a definition of diarrhea seems most important. At this point, I think pursuing research only on L. rhamnosus and S. boulardii would be most worthwhile, as these two organisms seem to be the most promising and this would eliminate heterogeneity between microorganisms tested.

References/PDFs
CAT_Probiotics.pdf

Guo_et_al-2019-Cochrane_Database_of_Systematic_Reviews.pdf
J pediatr gastroenterol nutr – 2016 – Szajewska – Probiotics for the Prevention of Antibiotic‐Associated Diarrhea in.pdf
Probiotics in the Management of Antibiotic-Associated Diarrhea in Children_A Systematic Review and Meta-analysis of Randomized and Controlled Trials.pdf
Hayes and Vargas.pdf
Lukasik et al.pdf
Yang et al..pdf

Clinical Question: 

54yof presents for evaluation of suspected viral sinusitis, reports she frequently and recurrently has viral respiratory infections. She states she heard from her PCP that vitamin D supplementation can help prevent colds. 

PICO Question: 

In the general adult population, does vitamin D supplementation prevent respiratory infections compared to placebo?

P	I	C	O
adults	Vitamin D supplementation	control	Incidence of respiratory infection
	D3 supplementation	placebo	Prevention of respiratory infection
	D2 supplementation		Rate of respiratory infection
	Cholecalciferol supplementation		Frequency of respiratory infection

Search Strategy: 

In searching for my articles, my strategy had a few different components. First, I limited my search results to be for articles from the past 10 years; however, results were abundant enough that I prioritized articles from the last 7 years only. I came across a bit of an obstacle in that the majority of the results I found were specifically about COVID-19. This makes a lot of sense given the applicability of that data within the last five years; However, I was aiming to research viral infections on a broader lens, so I had to prioritize articles that did not include COVID-19 in the title. Furthermore, I wanted to ensure that my chosen articles were highest level, so I included “review” as either a keyword or a search filter – Not only because they provide the highest level of evidence, but also because I know that my search question is fairly broad and rigorously researched, so I expected reviews to be plentiful. From there, I browsed articles and chose ones that thoroughly vetted the articles they included and specifically had analyses dedicated to more than one viral URI. 

1. CUNY York OneSearch → vitamin D supplement respiratory infection systematic review → 2014-2024 → 87 results
   1. I scrolled through the first 25 results. I prioritized peer-reviewed level 1 evidence studies with open access. I looked for articles from American journals. I looked for titles that best matched my PICO keywords. I avoided articles that made mention of specific viral infections such as COVID-19 or influenza. I opened 5 articles total and opted to include 3 of them here.
      1. The Jolliffe et al. article was the second result
      2. The Martineau et al. article was the third result
      3. The Cho et al. article was the 23rd result
2. NIH PMC → “vitamin D respiratory infection review” → 2014-2024 → 692 results
   1. I scrolled through the first 15 results. I looked for articles from American journals. I looked for titles that best matched my PICO keywords. I avoided articles that made mention of specific viral infections such as COVID-19 or influenza. I opened 4 articles but did not choose to include any of them. I strongly considered including a meta-analysis of the effect of vitamin D on various body systems, including respiratory amongst others, but I opted to keep looking for something more specific. I saw the 3 articles that I already selected amongst the results.
3. Google Scholar
   1. Being familiar with it, I know the Google Scholar algorithm tends to generate many more results than other search engines do. I opted to include more keywords in my search and limit my publish date filter more strictly than I did on the other search engines, in hopes of making my results more selective and applicable to my PICO.
      1. vitamin d supplementation respiratory infection review → 2020-2024 → 16,700 results
   2. I scrolled through two pages of results, and seeing how abundant they were while also noting that the overwhelming majority of them were specifically about COVID-19, I opted to limit my search to studies from the last year only
      1. vitamin d supplementation respiratory infection prevention review → Since 2023 → 16,900 results
         1. I scrolled through the first page of results, but keeping my search strategy in mind, none felt worthy of including in my PICO
   3. Given my equivocal findings amongst my articles so far, I really wanted something extremely recent. I broadened my study types but narrowed my years.
      1. vitamin d URI prevention review → since 2023 → 17,100 results
         1. The Jia et al. article was the first result
4. Struggling to find a 5th article, I returned to NIH PMC and modified some keywords to broaden my search → vitamin d supplementation respiratory infection → 10 years → 10,405 results
   1. I scrolled through the first 15 results, and I opened 2 studies that had potential to be applicable to my PICO following my general search strategy above
      1. The Rejnmark et al. article was the second result

Articles Chosen for Inclusion:

Article 1

Link	Vitamin D supplementation to prevent acute respiratory tract infections: systematic review and meta-analysis of individual participant data
Citation	Martineau AR, Jolliffe DA, Hooper RL, et al. Vitamin D supplementation to prevent acute respiratory tract infections: systematic review and meta-analysis of individual participant data. BMJ. 2017;356:i6583. Published 2017 Feb 15. doi:10.1136/bmj.i6583
Abstract	ObjectivesTo assess the overall effect of vitamin D supplementation on risk of acute respiratory tractinfection, and to identify factors modifying this effect.DesignSystematic review and meta-analysis of individual participant data (IPD) from randomized controlled trials.Data sourcesMedline, Embase, the Cochrane Central Register of Controlled Trials, Web of Science, ClinicalTrials.gov, and the International Standard Randomised Controlled Trials Number registry from inception to December 2015. eligibility criteria for study selectionRandomized, double blind, placebo controlled trials of supplementation with vitamin D3 or vitamin D2 of any duration were eligible for inclusion if they had been approved by a research ethics committee and if data on incidence of acute respiratory tract infection were collected prospectively and prespecified as an efficacy outcome.Results25 eligible randomized controlled trials (total 11 321 participants, aged 0 to 95 years) were identified. IPD were obtained for 10 933 (96.6%) participants. Vitamin D supplementation reduced the risk of acute respiratory tract infection among all participants (adjusted odds ratio 0.88, 95% confidence interval 0.81 to 0.96; P for heterogeneity <0.001). In subgroupanalysis, protective effects were seen in those receiving daily or weekly vitamin D without additional bolus doses (adjusted odds ratio 0.81, 0.72 to 0.91) but not in those receiving one or more bolus doses (adjusted odds ratio 0.97, 0.86 to 1.10; P forinteraction=0.05). Among those receiving daily or weekly vitamin D, protective effects were stronger in those with baseline 25-hydroxyvitamin D levels <25 nmol/L (adjusted odds ratio 0.30, 0.17 to 0.53) than in those with baseline 25-hydroxyvitamin D levels ≥25 nmol/L (adjusted odds ratio 0.75, 0.60 to 0.95; P for interaction=0.006). Vitamin D did not influence the proportion of participants experiencing at least one serious adverse event (adjusted odds ratio 0.98, 0.80 to 1.20, P=0.83). The body of evidence contributing to these analyses was assessed as being of high quality.ConclusionsVitamin D supplementation was safe and it protected against acute respiratory tract infection overall. Patients who were very vitamin D deficient and those not receiving bolus doses experienced the most benefit

Article 2

Link	Vitamin D supplementation to prevent acute respiratory infections: a systematic review and meta-analysis of aggregate data from randomized controlled trials
Citation	Jolliffe DA, Camargo CA Jr, Sluyter JD, et al. Vitamin D supplementation to prevent acute respiratory infections: a systematic review and meta-analysis of aggregate data from randomized controlled trials. Lancet Diabetes Endocrinol. 2021;9(5):276-292. doi:10.1016/S2213-8587(21)00051-6
Abstract	BackgroundA 2017 meta-analysis of data from 25 randomized controlled trials (RCTs) of vitamin D supplementation for the prevention of acute respiratory infections (ARIs) revealed a protective effect of this intervention. We aimed to examine the link between vitamin D supplementation and prevention of ARIs in an updated meta-analysis.Methods For this systematic review and meta-analysis, we searched MEDLINE, Embase, the Cochrane Central Register of Controlled Trials, Web of Science, and the ClinicalTrials.gov registry for studies listed from database inception to May 1, 2020. Double-blind RCTs of vitamin D3, vitamin D2, or 25-hydroxyvitamin D (25[OH]D) supplementation for any duration, with a placebo or low-dose vitamin D control, were eligible if they had beenapproved by a research ethics committee, and if ARI incidence was collected prospectively and prespecified as an efficacy outcome. Studies reporting results of long-term follow-up of primary RCTs were excluded. Aggregated study-level data, stratified by baseline 25(OH)D concentration and age, were obtained from study authors. Usingthe proportion of participants in each trial who had one or more ARIs, we did a random-effects meta-analysis to obtain pooled odds ratios (ORs) and 95% CIs to estimate the effect of vitamin D supplementation on the risk of having one or more ARIs (primary outcome) compared with placebo. Subgroup analyses were done to estimatewhether the effects of vitamin D supplementation on the risk of ARI varied according to baseline 25(OH)D concentration (<25 nmol/L vs 25·0–49·9 nmol/L vs 50·0–74·9 nmol/L vs >75·0 nmol/L), vitamin D dose (daily equivalent of <400 international units [IU] vs 400–1000 IU vs 1001–2000 IU vs >2000 IU), dosing frequency (daily vs weekly vs once per month to once every 3 months), trial duration (≤12 months vs >12 months), age at enrollment (<1·00 years vs 1·00–15·99 years vs 16·00–64·99 years vs ≥65·00 years), and presence versus absence of airway disease (ie, asthma only, COPD only, or unrestricted). Risk of bias was assessed with the Cochrane Collaboration Risk of Bias Tool. The study was registered with PROSPERO, CRD42020190633.Findings We identified 1528 articles, of which 46 RCTs (75 541 participants) were eligible. Data for the primary outcome were obtained for 48 488 (98·1%) of 49 419 participants (aged 0–95 years) in 43 studies. A significantly lower proportion of participants in the vitamin D supplementation group had one or more ARIs (14 332 [61·3%] of 23 364 participants) than in the placebo group (14 217 [62·3%] of 22 802 participants), with an OR of 0·92 (95% CI 0·86–0·99; 37 studies; I²=35·6%, pheterogeneity=0·018). No significant effect of vitamin D supplementation on the risk of having one or more ARIs was observed for any of the subgroups defined by baseline 25(OH)D concentration. However, protective effects of supplementation were observed in trials in which vitamin D was given in a daily dosing regimen (OR 0·78 [95% CI 0·65–0·94]; 19 studies; I²=53·5%, pheterogeneity=0·003), at daily dose equivalents of 400–1000 IU (0·70 [0·55–0·89]; ten studies; I²=31·2%, pheterogeneity=0·16), for a duration of 12 months or less (0·82 [0·72–0·93]; 29 studies; I²=38·1%, pheterogeneity=0·021), and to participants aged 1·00–15·99 years at enrolment (0·71 [0·57–0·90]; 15 studies; I²=46·0%, pheterogeneity=0·027). No significant interaction between allocation to the vitamin D supplementation group versus the placebo group and dose, dose frequency, study duration, or age was observed. In addition, no significant difference in the proportion of participants who had at least one serious adverse eventin the vitamin supplementation group compared with the placebo group was observed (0·97 [0·86–1·07]; 36 studies; I²=0·0%, pheterogeneity=0·99). Risk of bias within individual studies was assessed as being low for all but three trials. InterpretationDespite evidence of significant heterogeneity across trials, vitamin D supplementation was safe and overall reduced the risk of ARI compared with placebo, although the risk reduction was small. Protection was associated with administration of daily doses of 400–1000 IU for up to 12 months, and age at enrolment of 1·00–15·99 years. The relevance of these findings to COVID-19 is not known and requires further investigation.

Article 3

Link	Efficacy of Vitamin D Supplements in Prevention of Acute Respiratory Infection: A Meta-Analysis for Randomized Controlled Trials
Citation	Hae-Eun Cho, Seung-Kwon Myung, Cho H. Efficacy of Vitamin D Supplements in Prevention of Acute Respiratory Infection: A Meta-Analysis for Randomized Controlled Trials. Nutrients. 2022;14(4):818. doi:https://doi.org/10.3390/nu14040818
Abstract	Background: Previous systematic reviews and meta-analyses of randomized controlledtrials (RCTs) have reported inconsistent results regarding the efficacy of vitamin D supplements in the prevention of acute respiratory infections (ARIs). Methods: We investigated these efficacy results by using a meta-analysis of RCTs. We searched PubMed, EMBASE, and the Cochrane Library in June 2021. Results: Out of 390 trials searched from the database, a total of 30 RCTs involving 30,263 participants were included in the final analysis. In the meta-analysis of all the trials, vitamin D supplementation showed no significant effect in the prevention of ARIs (relative risk (RR) 0.96, 95% confidence interval (CI) 0.91–1.01, I2 = 59.0%, n = 30). In the subgroup meta-analysis, vitamin D supplementation was effective in daily supplementation (RR 0.83, 95% CI, 0.73–0.95, I2 = 69.1%, n = 15) and short-term supplementation (RR 0.83, 95% CI, 0.71–0.97, I2 = 66.8%, n = 13). However, such beneficial effects disappeared in the subgroup meta-analysis of high-quality studies (RR 0.89, 95% CI, 0.78–1.02, I2 = 67.0%, n = 10 assessed by the Jadad scale; RR 0.87, 95% CI, 0.66–1.15, I2 = 51.0%, n = 4 assessed by the Cochrane’s risk of bias tool). Additionally, publication bias was observed.Conclusions: The current meta-analysis found that vitamin D supplementation has no clinical effect in the prevention of ARIs

Article 4

Link	Vitamin D supplementation for prevention of acute respiratory infections in older adults: A systematic review and meta-analysis
Citation	Jia H, Sheng F, Yan Y, Liu X, Zeng B. Vitamin D supplementation for prevention of acute respiratory infections in older adults: A systematic review and meta-analysis. PLoS One. 2024;19(5):e0303495. Published 2024 May 24. doi:10.1371/journal.pone.0303495
Abstract	BackgroundAcute respiratory infections (ARIs) have a substantial impact on morbidity, healthcare utilization, and functional decline among older adults. Therefore, we systematically reviewed evidence from randomized controlled trials (RCTs) to evaluate the efficacy and safety of vitamin D supplementation in preventing ARIs in older adults. MethodsPubMed, Embase, the Cochrane Library, and ClinicalTrials.gov were searched until 1 February 2024. RCTs evaluating the use of vitamin D supplements to protect older adults from ARIs were included. Two reviewers independently screened papers, extracted the data and assessed the risk of bias. Data were summarized as relative risks (RRs) or odds ratios (ORs) with corresponding 95% confidence intervals (CIs). Random effects meta-analyses were used to synthesize the results. GRADE was used to evaluate the quality of evidence. All the analyses were performed with Stata version 17. ResultsTwelve trials (41552 participants) were included in the meta-analysis. It showed that vitamin D supplementation probably does not reduce the incidence of ARIs (RR, 0.99; 95% CI, 0.97–1.02, I2 = 0%; moderate certainty). No significant effect of vitamin D supplementation on the risk of ARI was observed for any of the subgroups defined by baseline 25(OH)D concentration, control treatments, dose frequency, study duration, and participants’ condition. However, there was a possibility, although not statistically significant, that vitamin D may reduce the risk of ARI in patients with a baseline 25(OH)D concentration <50 nmol/L (OR, 0.90; 95% CI, 0.79–1.04, I2 = 14.7%). Additionally, vitamin D supplements might result in little to no difference in death due to any cause, any adverse event, hypercalcinemia, and kidney stones. ConclusionsVitamin D supplementation among older adults probably results in little to no difference in the incidence of ARIs. However, further evidence is needed, particularly for individuals with vitamin D deficiency and populations residing in low and middle income countries.

Article 5

Link	Non-skeletal health effects of vitamin D supplementation: A systematic review on findings from meta-analyses summarizing trial data
Citation	Rejnmark L, Bislev LS, Cashman KD, et al. Non-skeletal health effects of vitamin D supplementation: A systematic review on findings from meta-analyses summarizing trial data. PLoS One. 2017;12(7):e0180512. Published 2017 Jul 7. doi:10.1371/journal.pone.0180512
Abstract	BackgroundA large number of observational studies have reported harmful effects of low 25-hydroxyvitamin D (25OHD) levels on non-skeletal outcomes. We performed a systematic quantitative review on characteristics of randomized clinical trials (RCTs) included in meta-analyses (MAs) on non-skeletal effects of vitamin D supplementation. Methods and findingsWe identified systematic reviews (SR) reporting summary data in terms of MAs of RCTs on selected non-skeletal outcomes. For each outcome, we summarized the results from available SRs and scrutinized included RCTs for a number of predefined characteristics. We identified 54 SRs including data from 210 RCTs. Most MAs as well as the individual RCTs reported null-findings on risk of cardiovascular diseases, type 2 diabetes, weight-loss, and malignant diseases. Beneficial effects of vitamin D supplementation was reported in 1 of 4 MAs on depression, 2 of 9 MAs on blood pressure, 3 of 7 MAs on respiratory tract infections, and 8 of 12 MAs on mortality. Most RCTs have primarily been performed to determine skeletal outcomes, whereas non-skeletal effects have been assessed as secondary outcomes. Only one-third of the RCTs had low level of 25OHD as a criterion for inclusion and a mean baseline 25OHD level below 50 nmol/L was only present in less than half of the analyses. ConclusionsPublished RCTs have mostly been performed in populations without low 25OHD levels. The fact that most MAs on results from RCTs did not show a beneficial effect does not disprove the hypothesis suggested by observational findings on adverse health outcomes of low 25OHD levels.

Summary of the Evidence:

Author (Date)	Level of Evidence	Sample/Setting(# of subjects/ studies, cohort definition etc. )	Outcome(s) studied	Key Findings	Limitations and Biases
Martineau et al., 2017	1 –  systematic review and meta-analysis	-Randomized, double blind, RCTs of supplementation with vitamin D3 or vitamin D2 of any duration-approved by a research ethics committee -data on incidence of acute respiratory tract infection were collected prospectively and prespecified as an efficacy outcome-Through December, 2015===-25 eligible randomized controlled trials-11,321 participants aged 0 to 95 years	Variable within individual included studies This SR primarily extracted and analyzed Incidence of respiratory tract infection amongst included RCTs	Vitamin D supplementation reduced the risk of acute respiratory tract infection among all participants  Subgroup Analysis: protective effects were seen in those receiving daily or weekly vitamin D without additional bolus doses, but not in those receiving one or more bolus doses  protective effects were stronger in those with baseline vitamin D levels <25 nmol/L than in those with baseline D levels ≥25 nmol/L	-Power to detect effects of vitamin D supplementation was limited for  individuals with baseline 25-hydroxyvitamin D concentrations <25nmol/L receiving bolus dosing regimens-Null and borderline statistically signifi-cant results for analyses of these outcomes may have arisen as a consequence of type 2 error-data relating to adherence to study drugs were not available for all participants-Definitions of acute respiratory tract infection are diverse, multi-etiological, and vary in clinical diagnosis
Jolliffe et al., 2019	1 –  systematic review and meta-analysis	-Double-blind RCTs of vitamin D3, vitamin D2, or 25-hydroxyvitamin D (25[OH]D) supplementation for any duration, with a placebo or low-dose vitamin D control-database inception to May 1, 2020-approved by a research ethics committee====-1528 articles identified, 46 RCTs included, N = -75, 541 participants, aged 0–95 years	Variable amongst individual included RCTs acute respiratory infection incidence was collected prospectively and prespecified as an efficacy outcome This SR/MA analyzed the primary outcome ofproportion of participants who had one or more ARIs Secondary outcomes:-URI, LRI, emergency department attendance for an ARI, hospital admissionfor an ARI, death due to ARI or respiratoryfailure; use of antibiotics to treat an ARI; absence fromwork or school due to an ARI; serious adverse events; adverse reactions to vitamin D	Protective effects of supplementation were observed in trials in which —vitamin D was given in a daily dosing regimen –at daily dose equivalents of 400–1000 IU –for a duration of 12 months or less –to participants aged 1·00–15·99 years at enrolment No significant interaction between allocation to the vitamin D supplementation group versus the placebo group and dose, dose frequency, study duration, or age was observed	-Heterogeneity between included studies-Despite thelarge number of trials overall, only eleven compared theeffects of lower-dose versus higher-dose vitamin Dsupplementation-unable to investigate race or ethnicity and obesity aspotential effect-modifiers-unable to account forother factors that might influence the protective effect of vitamin D supplementation in the prevention of ARIs(eg, taking the supplement with or without food), orsecular trends that would influence trial- unable to control for concurrent use of standard dose vitamin D supplementsor multivitamins in the placebo group -funnel plot suggests that the overall effect size might have been overestimated due to publication bias
Cho et al., 2023	1 –  systematic review and meta-analysis	-Through June 2021-RCTs that reported the efficacy of vitamin D supplements in the prevention of ARIs using outcome measures with dichotomous variables-Studies were stratified  using the Cochrane Risk of Bias Tool and the Jadad scale =====-Out of 390 trials searched from the database, a total of 30 RCTs involving 30,263 participants were included in the final analysis	Variable amongst individual included studies This SR/MA extracted the primary outcome of frequency of respiratory infections, including URIs (n = 23), LRIs (n = 6), and both URIs and LRIs (n = 1)	Vitamin D supplementation showed no significant effect in the prevention of ARIs  Subgroup meta-analysis: vitamin D supplementation was effective in daily supplementation and short-term supplementation However, beneficial effects disappeared in the subgroup meta-analysis of high-quality studies	-Baseline concentration of the 25(OH)D was not considered, -Publication bias was found in this study, which means that trials showing an increasing risk of or no effect on ARIs by vitamin D supplementation might not be published. This favors the conclusion that there is no preventive effect of vitamin D supplements on ARIs. -Several RCTs included were not designed specifically to investigate the efficacy of vitamin D supplements on ARIs as a primary endpoint
Jia et al., 2024	1 –  systematic review and meta-analysis	-Through February 2024-RCTs evaluating the effects of supplementary vitamin D3, vitamin D2, or 25(OH)D, regardless of dosage or duration, to prevent ARI in adults 50 years of age or older were included====12 trials, 41552 participants	Variable amongst individual RCTs Only studies with ARI as a prespecified efficacy outcome were included, however, the preventive effect of vitamin D supplements on ARIs was not the primary outcome in several included trials This SR/MA extracted incidence of acute respiratory tract infection as its primary outcome	No significant effect of vitamin D supplementation on the risk of ARI was observed for any of the subgroups (baseline 25(OH)D concentration, control treatments, dose frequency, study duration, and participants’ condition) There was a possibility, although not statistically significant, that vitamin D may reduce the risk of ARI in patients with a baseline 25(OH)D concentration <50 nmol/L	-Clinical and statistical heterogeneity between included studies-Unable to evaluate the differences in the preventive effect on ARIs between individuals with vitamin D deficiency and those with normal vitamin D levels-Analysis based on study-level data rather than individual patient data, which limited the power of our analysis and the investigation of potential effect-modifiers.
Rejnmark et al., 2017	1 – systematic review and meta-analysis	-through December 1st, 2016-SRs published in English within the last 10 years on findings from RCTs testing effects of vitamin D supplementations on selected outcomes-only included SRs reporting summary data in terms of MAs on effects of treatment with calciferol (vitamin D2 or D3) or activated vitamin D analogues in their summary estimate, as long as the majority (>50%) of included studies were on calciferol-The search for SRs on effects of vitamin D supplementation on risk of RTIs identified 10 SRs, among which seven reported MAs on pooled data from RCTs on risk of RTIs in response to vitamin D supplementation The seven MAs included data from a total of 30 RCTs.	23/30 (77%) of the RCTs investigated effects of vitamin D supplementation as a primary outcome, the remaining as a secondary outcome With some variability in phrasing or stratification between studies, this SR with MA evaluated the risk of respiratory tract infection by analysis of rate of infection amongst included data	A beneficial effect of vitamin D supplementation on risk of infections was found in nine (30%) of the trials Vitamin D supplementation was found to significantly reduce risk of RTI by approximately 40% in 2 MAs  1 MA, which excluded studies which were considered to be of low quality in terms of a modified Jadad score ≤ 3, found no beneficial effects of vitamin D supplementation on risk of RTI A recent individual patient data analysis (IPD) showed a significantly reduced risk of acute RTI. Sub-group analyses suggested protective effects in response to  daily or weekly vitamin D dose, but not in response to one or more bolus doses protective effects were stronger in those with a baseline 25OHD <25 nmol/L than in those with a baseline 25OHD ≥25 nmol/L	-Only two studies were of a large scale with more than 1000 participants-Most studies had a relatively short duration-Only one of the trials had low 25OHD levels (< 50 nmol/L) as inclusion criteria and mean 25OHD levels at baseline were only reported in two-thirds of the studies among which only seven trials reported mean levels below 50 nmol/L

Conclusion(s):
Jolliffe et al: Vitamin D supplementation was safe and overall reduced the risk of ARI compared with placebo, although the risk reduction was small. Protection was associated with administration of daily doses of 400–1000 IU for up to 12 months, and age at enrolment of 1-16 years

Martineau et al.: Vitamin D supplementation was safe and it protected against acute respiratory tract infection overall. Patients who were very vitamin D deficient and those not receiving bolus doses experienced the most benefit.

Cho et al: Vitamin D supplementation has no clinical effect in the prevention of ARIs. Although subgroup analysis found vitamin D supplementation to be effective in daily and short-term supplementation, this was only seen in low-quality studies and disappeared in the subgroup meta-analysis of high-quality studies.

Jia et al: Vitamin D supplementation among older adults probably results in little to no difference in the incidence of ARIs. However, further evidence is needed, particularly for individuals with vitamin D deficiency.

Rejnmark et al.: The overall findings suggest a beneficial effect of vitamin D on respiratory tract infections. However, most published studies on effects of vitamin D supplementation on risk of RTI have been relatively small and of short duration without specifically addressing effects in populations with vitamin D insufficiency. Furthermore, the populations studied have varied widely from newborns to elderly as well as effects of a wide range of different types of infections, raising the question whether results from such different settings can be merged into MA reporting summary estimates. 

Two of my included articles found a significant protective benefit of vitamin D supplementation against respiratory viruses, another two find no clinical effect, and one supports the potential benefit of vitamin D on the rate of respiratory infections while acknowledging that the studies they analyzed are not of the highest quality to strongly support such a conclusion. In other words, recent studies vary and even contradict each other significantly. The two studies that found a significantly overall protective benefit of vitamin D supplementation against respiratory viruses are the oldest studies I analyzed, and did not highlight any subgroup analysis considering the quality of studies. The three studies that found little to no effect are newer studies that included the most recent RCTs and also specifically did subgroup analyses considering the quality of each study included. It is important to consider these factors while developing my clinical bottom.

Clinical Bottom Line:

It remains equivocal whether or not Vitamin D supplementation prevents viral respiratory infections in adult patients. Although multiple high quality studies have found a statistically significant benefit, this effect disappears in more recent analyses that include analysis of only high quality studies, according to objective criteria such as JADDAD or AMSTAR grading. Therefore, weighing the evidence, I must value the findings of the newer, larger, and more rigorous analyses by Cho, Jia, and Rejnmark more than I do the older and less rigorous analyses. Also of note, the Jolliffe and Martineau articles share some authors, so their respective findings might be biased to validate each other. Therefore, vitamin D supplementation does not have a large magnitude of effect on the prevention of viral infection. Most articles found no effect, and some concluded the possibility of a small effect. Therefore, I can confidently conclude the effect is little to none. Considering clinical significance, I would still suggest that my patients who are hoping to prevent viral respiratory infections take vitamin D supplementation. There does seem to be potential for some overall beneficial effect without much risk for adverse events, so I think the potential benefit of supplementation outweighs any very low risk. Specifically, I would tell them that multiple analyses found that smaller daily dosing seems to carry more benefit than more intense dosing regimens, and there seems to be a higher potential benefit in patients who are Vitamin D deficient, and in pediatric patients. I would be sure to emphasize that the effect of vitamin D supplementation on the rate of respiratory infection requires more research in the future, so I would not endorse to my patients that this supplementation prevents respiratory infections with any certainty. It’s also important to keep in mind that correlation does not equal causation, as many studies noted the limitation that patients who take Vitamin D supplements may or may not also be taking other vitamin supplements or be generally healthier/more active in maintaining their health. Overall, newer studies contradict older studies, so this research question requires more analysis in the future.