Retrospective database analysis of 374,229 patients in the USA, showing no significant difference with HCQ use, however authors do not adjust for the very different baseline risk for systemic autoimmune disease patients. Other research shows that the risk of COVID-19 for systemic autoimmune disease patients is much higher overall, Ferri et al. show OR 4.42, p
Authors compare with patients that never used HCQ and with patients that previously used HCQ. The comparison with patients previously using HCQ is more relevant because the matching of patients with systemic autoimmune disease is likely to be better.
Fung et al., 10/1/2021, retrospective, population-based cohort, USA, North America, preprint, 6 authors.
risk of death, 15.0% lower, RR 0.85, p = 0.10, vs. past use (better match for systemic autoimmune diseases).
risk of hospitalization, 5.0% lower, RR 0.95, p = 0.41, vs. past use (better match for systemic autoimmune diseases).
risk of COVID-19 case, 10.0% lower, RR 0.90, p = 0.004, vs. past use (better match for systemic autoimmune diseases).
risk of death, 6.0% higher, RR 1.06, p = 0.39, vs. never used.
risk of hospitalization, 4.0% higher, RR 1.04, p = 0.32, vs. never used.
risk of COVID-19 case, 5.0% lower, RR 0.95, p = 0.06, vs. never used.
This study is excluded in the after exclusion results of meta analysis: not fully adjusting for the different baseline risk of systemic autoimmune patients.
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.