Retrospective 683 patients in a rheumatology department, 384 chronic HCQ users and 299 control patients, showing no mortality for HCQ users vs. 2 deaths in the control group, and significantly fewer cases for HCQ users.
Korkmaz et al., 6/1/2021, retrospective, Turkey, Europe, preprint, 4 authors.
risk of death, 82.1% lower, RR 0.18, p = 0.19, treatment 0 of 385 (0.0%), control 2 of 299 (0.7%), continuity correction due to zero event (with reciprocal of the contrasting arm).
risk of COVID-19 case, 93.7% lower, RR 0.06, p < 0.001, treatment 2 of 395 (0.5%), control 24 of 299 (8.0%).
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.