Is antimalarial use associated with a reduced risk of LN in patients with SLE? Results from an inception cohort-based study.

OBJECTIVES Antimalarials are a cornerstone in managing SLE and are associated with multiple favourable disease outcomes. This study explored whether antimalarial use is associated with a reduced risk of incident LN in SLE patients. METHODS We included SLE patients from an inception cohort with no prior history of LN, followed prospectively at regular intervals. The relationship between the exposure (cumulative duration of antimalarial exposure in years) and the outcome (development of LN, as indicated by new-onset proteinuria attributed to lupus activity by clinical judgement and recorded in the SLEDAI-2K sheet) was characterized using a time-dependent univariable Cox proportional hazards model to estimate the overall effect. Adjusted multivariable Cox regression was also employed to estimate the risk of LN, incorporating clinically relevant variables. RESULTS The study included 674 inception SLE patients, with a median baseline age of 33.6 years (interquartile range [IQR]: 24.9-45.4). One hundred and fifty-four patients (22.8%) developed SLE-related new-onset proteinuria, indicating LN, with a median time to event of 3.6 years [IQR: 0.9-8.8]. Cumulative duration of antimalarial exposure was not significantly associated with a lower risk of LN, either in the unadjusted univariable model estimating the overall effect (hazard ratio [HR]: 0.98; 95% CI: 0.94-1.02, P = 0.25) or in the adjusted multivariable model (HR: 0.96; 95% CI: 0.92-1.00, P = 0.08). This finding was also corroborated in a sensitivity analysis of patients with serologically active SLE (HR: 0.97; 95% CI: 0.92-1.02). CONCLUSION Antimalarial use is not significantly associated with a reduced risk of incident LN in SLE patients.