Antimalarials in the treatment of systemic lupus erythematosus: a registry-based cohort study in Denmark

Background Evidence-based international guidelines for the treatment of systemic lupus erythematosus (SLE) recommend treatment with antimalarials (AMs) for all patients with SLE irrespective of disease activity. Only a few studies have investigated the use of AMs among newly diagnosed patients with SLE. Objectives The objective of this paper is to analyze prescription patterns of AMs in newly diagnosed SLE patients in Denmark from 2000 to 2011. Methods Using the Danish Prescription Register (DNPR), we conducted a nationwide cohort study including all patients with a first-time diagnosis of SLE (the Danish National Registry of Patients (NPR)). We used Kaplan-Meier estimates to compute the cumulative probability of starting AM treatment within a year and Cox regression analysis to compare time to treatment between patient groups. Results AMs were prescribed to 37.7% of the newly diagnosed SLE patients within the first year of follow-up. Approximately 20% did not receive any medical treatment. Women were more likely than men to start AM (adjusted HR of 1.28 (95% CI 1.08-1.52)). Patients diagnosed with SLE between 2005 and 2011 were more likely to start treatment than patients diagnosed between 2000 and 2004 (HR of 1.21 (95% CI 1.07-1.36)). Patients with renal disease were less likely to start AM treatment than patients without this condition (adjusted HR of 0.50 (95% CI 0.36-0.68)). Current users of corticosteroids were more likely to start AM treatment than non-users (adjusted HR 1.81 (95% CI 1.59-2.06)). Conclusion Time to start of AM treatment following SLE diagnosis could be further reduced, especially among patients with renal disease. However, our results showed that treatment practice in recent years has changed toward initiating AM treatment earlier.