Retrospective 93 hospitalized patients with vitamin D levels 1-365 days before admission, not showing significant differences with vitamin D deficiency or vitamin D levels. Vitamin D levels may vary significantly throughout the year creating a major cofounder that authors do not adjust for.
Szeto et al., 12/30/2020, retrospective, USA, North America, peer-reviewed, 7 authors.
risk of death, 5.6% higher, RR 1.06, p = 1.00, high D levels 14 of 58 (24.1%), low D levels 8 of 35 (22.9%).
risk of mechanical ventilation, 39.7% lower, RR 0.60, p = 0.21, high D levels 10 of 58 (17.2%), low D levels 10 of 35 (28.6%).
risk of no hospital discharge, 26.7% higher, RR 1.27, p = 0.50, high D levels 21 of 58 (36.2%), low D levels 10 of 35 (28.6%).
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.