Subgroup analyses.

Error bars indicate 95% confidence intervals of OR in subgropus of randomized trials. Subgroups were based on RTI being a primary or secondary endpont, trial participants being patients or healthy individuals, children or adults, and vitamin D-sufficient or insufficient, and vitamin D being adminstered daily or as bolus doses. Numbers indicate number of trials in each subgroup and p-values refer to between-group differences in random effects meta-regressions performed separately for each pair of subgroups.