Effect of vitamin A supplementation on childhood morbidity and mortality: critical review of Indian studies

Abstract

Objective: To review all published randomized trials concerned with linkage of vitamin A supplementation with reduction of mortality and morbidity in Indian children. Method: The studies were identified by searching the PubMed, review articles, references of available meta-analyses and bibliography of pertinent references. Studies were extracted and the quality of each study was reviewed with regards to 10 categories of parameters that in our opinion, were important for a vitamin A prophylaxis trial. These included background indicators, subjects, design, intervention, proximal measures, field-work, sources of bias, data analysis, interpretation and documentation. Results: Out of 12 studies satisfying the inclusion criteria, the available 11 were examined. Two of the trials were concerned with mortality, 6 with morbidity, and 2 with both mortality and morbidity; 1 study assessed the impact of vitamin A on pneumococcal colonization. Out of 4 mortality trials, only one could satisfactorily report a significant reduction (54%) in child mortality following vitamin A supplementation. Of 8 morbidity studies, only 3 indicated some beneficial effect of vitamin A supplementation. None of the studies was perfect in methodology. We could not locate any study that addressed the issue of cost-effectiveness or dietary modifications. The results were not unequivocal and findings for mortality and morbidity were not corroborative. Conclusion: There is no definite evidence as yet in favor or against substantial benefit of universal vitamin A supplementation to children in India. There is a clear need to undertake a comprehensive trial with adequate sample size and a standardized methodology that could give clear, unbiased, and convincing evidence on the role of routine vitamin A supplementation.