COVID-19 and rheumatic autoimmune systemic diseases: report of a large Italian patients series
Analysis of 1641 systemic autoimmune disease patients showing csDMARD (HC
Q etc.) RR 0.37, p=0.015.
csDMARDs include HC
Q, and several other drugs, so the effect of HC
Q 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).
(reults 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).