Retrospective 80 COVID-19 patients showing low vitamin D levels associated with severity and mortality.
Karonova et al., 12/31/2020, retrospective, Russia, Asia, Europe, peer-reviewed, 3 authors.
risk of death, 79.4% lower, RR 0.21, p = 0.07, high D levels 1 of 23 (4.3%), low D levels 12 of 57 (21.1%), odds ratio converted to relative risk, >20ng/ml.
risk of COVID-19 severe case, 71.1% lower, RR 0.29, p = 0.02, high D levels 3 of 23 (13.0%), low D levels 22 of 57 (38.6%), odds ratio converted to relative risk, >20ng/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.