Relapse risk of lupus-related serositis according to immunosuppressive therapy: a national real-world study

Background Management of systemic lupus erythematosus (SLE) is largely guided by organ involvement. Serositis affects up to 46% of patients, yet its treatment is mainly empirical and extrapolated from other manifestations, and long-term outcome data remain limited. We aimed to evaluate short-term response to anti-inflammatory therapy and to examine associations between immunosuppressive treatments and serositis relapse. Methods We conducted a multicentre retrospective real-world study in patients with SLE with pericarditis and/or pleuritis, identified through a nationwide call for case reporting. Initial response was defined as symptom and sign resolution at early reassessment. Relapse was defined as recurrence requiring treatment intensification ≥3 months after the index flare. Relapse-free survival was described by Kaplan–Meier methods and analysed as recurrent events using a Prentice-Williams-Peterson gap-time Cox model adjusted for prespecified confounders. Results One hundred patients contributed 180 serositis episodes (161 pericarditis, 51 pleuritis, associated in 32 cases) over a mean follow-up of 91 months; 46% experienced ≥1 relapse. Overall, 108/124 (87.1%) of evaluable episodes responded to initial anti-inflammatory therapy, with no significant difference between corticosteroid-based and aspirin/colchicine regimens. Corticosteroid use was not associated with increased relapse risk (46.0% vs 46.2%, p=0.98). Conventional immunosuppressants (methotrexate, azathioprine, mycophenolate mofetil) were not associated with reduced relapse risk, whereas belimumab was associated with lower relapse risk (HR=0.34, 95% CI 0.14 to 0.84; p=0.019). Conclusion Lupus-related serositis is frequent and highly relapsing. In this national cohort, belimumab—but not conventional immunosuppressants—was associated with reduced serositis recurrence, supporting its further evaluation in lupus serositis.