OBJECTIVES: To ascertain if hydroxychloroquine (HCQ) /chloroquine (CLQ) and other conventional disease-modifying anti-rheumatic drugs (cDMARDs) use, and rheumatic diseases per se, may be associated with COVID-19-related risk of hospitalization and mortality .
METHODS: This case-control study nested within a cohort of cDMARD users was conducted in the Lombardy, Veneto, Tuscany and Lazio regions and Reggio Emilia province . Claims databases were linked to COVID-19 surveillance registries . Risk of COVID-19-related outcomes was estimated using a multivariate conditional logistic regression analysis, comparing HCQ/CLQ vs methotrexate, vs other cDMARDs and vs non-use of these drugs . Presence of rheumatic diseases vs their absence in a non-nested population was investigated .
RESULTS : 1275 cases hospitalized due to COVID-19 were matched to 12 734 controls . Compared with recent use of methotrexate, no association between HCQ/CLQ monotherapy and COVID-19 hospitalization (OR 0.83 [95% CI , 0.69-1.00] ) or mortality (OR 1.19 [95% CI , 0.85-1.67] ) was observed . A lower risk was found when comparing HCQ/CLQ use to the concomitant use of other cDMARDs and glucocorticoids . HCQ/CLQ was not associated with COVID-19 hospitalization as compared with non-use . An increased risk for recent use of either methotrexate monotherapy (OR 1.19 [95% CI , 1.05-1.34] ) or other cDMARDs (OR 1.21 [95% CI , 1.08-1.36] ) vs non-use was found . Rheumatic diseases were not associated with COVID-19-related outcomes .
CONCLUSION: HCQ/CLQ use in rheumatic patients was not associated with a protective effect against COVID-19-related outcomes . Use of other cDMARDs was associated with an increased risk when compared with non-use, and, if concomitantly used with glucocorticoids, also vs HCQ/CLQ, probably to be ascribed to immunosuppressive action.