Analysis of 1641 systemic autoimmune disease patients showing csDMARD (HCQ etc.) RR 0.37, p
csDMARDs include HCQ, CQ, and several other drugs, so the effect of HCQ/CQ alone could be higher.
This study also confirms that the risk of COVID-19 for systemic autoimmune disease patients is much higher overall, OR 4.42, p
<0.001 (this is the observed real-world risk which takes into account factors such as these patients potentially being more careful to avoid exposure).
(results are for "definite + highly suspected" cases and the main result is presented in the paper as the OR for not taking csDMARDs, we have converted this to RR for taking csDMARDs).
Ferri et al., 27 Aug 2020, retrospective, Italy, peer-reviewed, survey, 29 authors.