Abstract / Summary
Background: The results of randomized controlled trials (RCTs) regarding the effect of vitamin D supplementation on mortality reduction are conflicting.
Objective: The aim of this study was to assess the level of evidence through a sensitivity analysis of the meta-analysis by Shah et al. (2024) using the Rebuilt the Evidence Base (REB) method.
Methods: The main inclusion criterion was a double-blind, placebo-controlled RCT design. The exclusion criteria were trials combining vitamin D with other nutrients and unpublished RCTs. The main outcome was all-cause mortality. A bias analysis was performed, followed by a hypothetico-deductive analysis to determine the confirmatory or exploratory nature of each RCT. The REB method was used to interpret the results and assess the level of evidence.
Results: Among the 25 RCTs included in the meta-analysis by Shah et al., the analysis was performed on 8 RCTs at low risk of bias including 30 320 participants. Seven RCTs raised some concerns, and two RCTs were at high risk of bias according to ROB2. Bias arose from the randomization process, deviations from intended interventions, missing outcome data, and selection of the reported results. The results were statistically significant, in favor of vitamin D supplementation: RR = 0.96 (95% CI [0.92, 1.00]), p = 0.04. No RCT was conclusive.
Conclusion: According to the REB method, there is an evidence signal regarding the benefit of vitamin D supplementation in the population aged 75 and older, which remains to be confirmed.