et al., European Journal of Pediatrics, doi:10.1007/s00431-021-04030-1 (Peer Reviewed)
Retrospective 103 pediatric hospitalized COVID-19 patients, showing an association between vitamin D deficiency and clinical severity.
Bayramoğlu et al., 3/31/2021, retrospective, Turkey, Europe, peer-reviewed, 7 authors.
risk of moderate/severe case, 69.5% lower, RR 0.30, p < 0.001, high D levels 10 of 60 (16.7%), low D levels 24 of 43 (55.8%), adjusted per study, odds ratio converted to relative risk, >12 ng/mL, multivariate logistic regression.
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.