Retrospective HCQ users in Denmark, not showing a significant difference, however authors do not adjust for the very different baseline risk for systemic autoimmune disease patients.
Authors appear unaware of research in the area, for example saying that "currently, no obvious connection exists between a known rheumatological disorder and the risk of contracting SARS-CoV-2". Many papers show that the risk of COVID-19 for systemic autoimmune disease patients is much higher overall, e.g., Ferri et al. show OR 4.42, p
Supplementary data is not currently available.
Kamstrup et al., 6/1/2021, retrospective, population-based cohort, Denmark, Europe, peer-reviewed, 21 authors.
risk of hospitalization, 44.0% higher, RR 1.44, p = 0.25, treatment 5488, control 54846, RR approximated with OR.
risk of COVID-19 case, 10.0% lower, RR 0.90, p = 0.23, treatment 188 of 5488 (3.4%), control 2040 of 54846 (3.7%), adjusted Cox proportional hazards regression.
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.