The risk of hospitalized infection in patients with systemic lupus erythematosus treated with hydroxychloroquine

Objective To compare the risk of hospitalized infection (HI) between users and non-users of hydroxychloroquine (HCQ) in systemic lupus erythematosus (SLE). Methods Using claims data, patients were defined as SLE cases by the following criteria: 1) they had at least one SLE diagnostic code; 2) they had a prescription for specific drugs, including corticosteroids, steroid pulse therapy, and immunosuppressive drugs; and 3) they were at least 16 years old between September 2015 and July 2017 (n = 17,483). The SLE cases with at least one prescription for HCQ were defined as the HCQ group (n = 1,431), while the others were defined as the non-HCQ group. Among the SLE cases, propensity score-matched cases were observed for 1 year (n = 1,095 in each group). Results The median age and proportion of female patients in both groups were about 42 years and 88%, respectively. The proportions of cases with HIs were similar (HCQ group, 4.5%; non-HCQ group, 5.6%; p = 0.240, McNemar test). The hazard ratio of the HCQ group for HIs after adjusting for patients' characteristics was not significant at 0.9 (0.6-1.3). Conclusion The use of HCQ was not associated with a risk of HIs in patients with SLE.