Prevalence, clinical associations and outcomes of pericarditis in systemic lupus erythematosus: insights from the University of Toronto Lupus Clinic

OBJECTIVE: Pericarditis is an important clinical feature in the classification criteria and disease activity indices in SLE. We aimed to study the prevalence, associations and outcomes of pericarditis in SLE. METHODS: This was an observational cohort study conducted at the University of Toronto Lupus Clinic (July 1970-March 2024). The prevalence of pericarditis was determined in both inception (enrolled within 1 year of diagnosis) and prevalent cohorts. The outcomes of pericarditis were defined as acute (resolution <3 months), chronic (lasting ≥3 months) and relapsing (recurrence after complete resolution). Associations with pericarditis and its outcomes were studied. RESULTS: Pericarditis was identified in 428 of 2122 patients (20.16%), 205 of 900 (22.8%) in inception and 223 of 1222 (18.2%) in the prevalent cohort. It developed early in the disease course (median 0.51 years). Among 170 patients, the median chest pain severity was 6 of 10. Associated myocarditis was observed in 5.3%, endocarditis in 1.9% and cardiac tamponade in 1.4%. Pericarditis was associated with higher SLEDAI-2000 [1.06 (1.001, 1.13)], anti-La antibodies [1.52 (1.01, 2.31)], constitutional features [1.98 (1.39, 2.81)] and less skin involvement [0.34 (0.21, 0.55)] in multivariable analysis. Most patients (79.5%) had resolution within 3 months. Chronic pericarditis occurred in 15.6% (median 4.6 months) and relapses in 22.9%. No significant associations were found for chronicity or relapse. CONCLUSION: Pericarditis affects one in five SLE patients, usually early in the disease. Most cases resolve in 3 months, but a subset experiences chronic or relapsing disease.