PT6:02 Heart failure and cardiomyopathy in systemic lupus erythematosus and the effect of hydroxychloroquine

Objectives We examined the association between systemic lupus erythematosus (SLE) and the risk of heart failure and cardiomyopathy (HF/CM) and assessed whether initiation and duration of hydroxychloroquine (HCQ) influence this risk.Methods This population-based cohort study utilized Swedish nationwide register data to identify all individuals aged 18-80 with newly diagnosed SLE in Sweden between 2006-08-01 and 2022-12-31, and matched general population comparators without SLE on sex, residence, and age at 1st SLE diagnosis. The primary outcome was a composite of HF or CM. Secondary outcomes included HF, CM, ischemic, and non-ischemic HF. Flexible parametric survival models estimated time-varying hazard ratios and 95% confidence intervals (HR 95%CI) comparing SLE vs. non-SLE. In patients with SLE, we applied two target trial emulations with the cloning-censoring-weighting approach to estimate the effect of HCQ initiation within 6 months of diagnosis compared to no initiation and the effect of treatment duration (6 years) on 10-year risk of HF/CM. Weighted pooled logistic models derived risk difference and risk ratio (RR). Analyses were adjusted for time-fixed (e.g., baseline age, sex) and time-varying confounders (e.g., glucocorticoids, immunosuppressants, comorbidities).Results We included 3,468 patients with incident SLE and 33,210 matched comparators. Over a median follow-up of 9 years, HF/CM incidence rate was 8.5 per 1,000 person-years for SLE vs. 3.7 per 1,000 person-years for non-SLE. The HRs (95%CIs) were 3.28 (2.58-4.18) at 1 year, 1.81 (1.53–2.14) at 5 years, and 1.59 (1.28–1.96) at 10 years. Associations were consistent across secondary outcomes ( table 1). In patients, the 10-year risk of HF/CM was 8.9% among HCQ initiators vs. 15.3% among non-initiators (RR 0.59 [0.46–0.74] and risk difference -8.6% [-11.9 to -5.0%]) (figure 1). Among initiators, treatment duration was not associated with HF/CM: the 10-year RRs were 0.88 (0.63–1.25) for 3-6 years and 0.92 (0.65–1.27) for >6 years vs.