Retrospective 205 patients in Iran, showing higher mortality with vitamin D deficiency, not quite reaching statistical significance.
Tehrani et al., 1/25/2021, retrospective, Iran, Middle East, peer-reviewed, 5 authors.
risk of death, 47.5% lower, RR 0.52, p = 0.07, high D levels 34 of 180 (18.9%), low D levels 9 of 25 (36.0%), >10ng/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.