PSM observational study with a database of 26,779 patients in the USA, showing significantly lower risk of PCR+ with melatonin usage.
Zhou et al., 11/6/2020, retrospective, propensity score matching, USA, North America, peer-reviewed, 18 authors.
risk of COVID-19 case, 21.1% lower, RR 0.79, p < 0.001, treatment 222 of 1055 (21.0%), control 8052 of 25724 (31.3%), odds ratio converted to relative risk, PSM.
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.