Retrospective database analysis showing patients with vitamin D deficiency were 4.6 times more likely to be COVID-19 positive, p
Katz et al., 12/4/2020, retrospective, USA, North America, peer-reviewed, 3 authors.
risk of COVID-19 case, 78.4% lower, RR 0.22, p < 0.001, adjusted per study.
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