Efficacy of high-dose vitamin D in pediatric asthma: a systematic review and meta-analysis

Abstract

Context: Observational studies have suggested a relationship between vitamin D status and asthma-related respiratory outcomes. The benefit of vitamin D supplementation for pulmonary function, symptoms and exacerbations is not well established. Objective: To systematically review paediatric clinical trials investigating the role of vitamin D on asthma-related respiratory outcomes. Data sources: MEDLINE, EMBASE and CENTRAL were searched until January 2014. No date or language restrictions. Study selection: Clinical trials reporting asthma-related respiratory outcomes following vitamin D administration at a dose equal or greater than 500 IU per day were included and reviewed independently by two authors for full systematic review eligibility. Data extraction: Two reviewers independently extracted and verified pre-defined data fields. Results: We identified five studies that met study eligibility and assessed final data synthesis. The median trial size was 48 participants (range 17–430) and the average daily dose of cholecalciferol ranged from 500 to 2000 IU/day. Overall study methodological quality was high, but some heterogeneity in population and vitamin D dosing regimen was evident. Meta-analysis suggested a statistically significant reduction (RR 0.41, CI 0.27–0.63) in asthma exacerbation with vitamin D therapy. Limitations: Due to variability in outcome selection and missing data, it was not possible to perform meta-analysis for pulmonary function testing and asthma symptom scores. Vitamin D-related adverse events were not considered in four of five papers. Conclusions: Available evidence from this systematic review suggests that high dose vitamin D may prevent asthma exacerbation. This should be confirmed through larger well-designed randomised controlled trials.

• Asthma
• asthma-related respiratory outcomes
• children
• systematic review
• Vitamin D

Acknowledgments

Authors thank Margaret Sampson, MLIS, PhD, AHIP (Children’s Hospital of Eastern Ontario) for developing the electronic search strategies, and Lorie Kloda, MLIS, PhD, (McGill University Library; John W. Scott Health Sciences Library, University of Alberta) for peer review on the MEDLINE search strategy. Nick Barrowman and Abdool Yasseen, Research Institute, Children’s Hospital of Eastern Ontario for giving advice in data analysis.

Declaration of interest

This study was supported by Children’s Hospital of Eastern Ontario Research Institute (Summer studentship, KI) and the Faculty of Medicine, University of Ottawa.

Supplementary material available online

Supplementary Appendix Tables SA1–SA6