Retrospective 508 hospitalized COVID-19 patients in Iran showing lower mortality with vitamin D supplementation (not reaching statistical significance), and an association between lower vitamin D levels and disease severity, ICU admission, and increased mortality. Details of supplementation are not provided. The multivariate result for vitamin D deficiency is in the preprint, the journal version only contains the multivariate result for serum level.
Vasheghani et al., 1/18/2021, retrospective, Iran, Middle East, preprint, 6 authors, dosage not specified.
risk of death, 30.4% lower, RR 0.70, p = 0.45, treatment 7 of 88 (8.0%), control 48 of 420 (11.4%), vitamin D supplementation.
risk of ICU admission, 63.8% lower, RR 0.36, p = 0.009, treatment 13 of 185 (7.0%), control 53 of 323 (16.4%), adjusted per study, vitamin D levels >30ng/mL.
Effect extraction follows pre-specified rules
prioritizing more serious outcomes. For an individual study the most serious
outcome may have a smaller number of events and lower statistical signficance,
however this provides the strongest evidence for the most serious outcomes
when combining the results of many trials.