Hydroxychloroquine and Cardiovascular Events in Patients With Systemic Lupus Erythematosus.

Importance: Systemic lupus erythematosus (SLE) predisposes individuals to early cardiovascular (CV) events. While hydroxychloroquine is thought to mitigate CV risk factors, its protective role against CV events, particularly arterial ones, remains to be confirmed. Objective: To evaluate the association between hydroxychloroquine and the risk of myocardial infarction (MI), stroke, and other thromboembolic events (OTEs) in patients with SLE. Design, Setting, and Participants: This cohort study using a nested case-control design was conducted within the National French Healthcare Database (SNDS), which represents 99% of the French population, from 2010 to 2020. Participants were the cohort of all patients with SLE recorded in the SNDS. Patients with SLE experiencing CV events during the study period were the case group; those without CV events were controls. The analysis period was from February 2022 to September 2023. Exposures: Hydroxychloroquine use within 365 days prior to the index date, defined as current (within 90 days), remote (91-365 days), or no exposure within the previous 365 days. Main Outcomes and Measures: Outcomes of interest were MI, stroke, and OTE, analyzed individually and as a composite outcome (primary analysis). Controls were matched to patients with CV events by age, sex, time since SLE onset and entry into the SNDS database, index date, prior antithrombotic and CV medication, chronic kidney disease, and hospitalization. Multivariable conditional logistic regression was performed using hydroxychloroquine exposure as the main independent variable. Results: The SLE cohort included 52 883 patients (mean [SD] age, 44.23 [16.09] years; 45 255 [86.6%] female; mean [SD] follow-up, 9.01 [2.51] years), including 1981 patients with eligible CV events and 16 892 matched control patients. There were 669 MI events, 916 stroke events, and 696 OTEs in the individual outcome studies. For current exposure to hydroxychloroquine, the adjusted odds were lower for composite CV events (odds ratio [OR], 0.63; 95% CI, 0.57-0.69) as well as for MI (OR, 0.72; 95% CI, 0.60-0.85), stroke (OR, 0.69; 95% CI, 0.60-0.81), and OTEs (OR, 0.58; 95% CI, 0.49-0.69) individually compared with no hydroxychloroquine exposure within 365 days. Conclusions and Relevance: In this nationwide cohort study of patients with SLE, a protective association was found between the current use of hydroxychloroquine and the occurrence of CV events, but not between remote use of hydroxychloroquine and CV outcomes, highlighting the value of continuous hydroxychloroquine treatment in patients with SLE.