Case control study in China comparing 62 patients with 80 healthy controls showing vitamin D deficiency is a risk factor for COVID-19, especially for severe/critical cases.
Ye et al., 10/13/2020, retrospective, China, Asia, peer-reviewed, 18 authors.
risk of severe/critical COVID-19, 93.4% lower, RR 0.07, p = 0.03, high D levels 2 of 36 (5.6%), low D levels 8 of 26 (30.8%), adjusted per study, >50nmol/L.
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.