Overall Survival and Treatment Patterns Among Patients With Warm Autoimmune Hemolytic Anemia in Sweden: A Nationwide Population-based Study.

Objectives: Warm autoimmune hemolytic anemia (wAIHA) is a rare autoantibody-mediated disorder, and first-line treatment primarily relies on corticosteroids. This study assessed overall survival (OS) and treatment patterns of wAIHA in Sweden.

Methods: Adults with ≥ 1 primary diagnosis code for wAIHA (or AIHA plus oral corticosteroids (OCS)/immunosuppressants as sensitivity analyses) between 2011 and 2022 were identified from five Swedish national registers and linked through each patient's unique identity number. Kaplan-Meier curves with log-rank tests and Cox regressions were performed to assess OS for patients with primary versus secondary wAIHA and patients with wAIHA and long-term versus short-term (≥ 3 vs. < 3 months) OCS users.

Results: The main analysis included 292 patients; 1791 patients were included in the sensitivity analysis. At a median 3.7-year follow-up, a median OS in primary wAIHA was not reached versus 6.0 years for secondary wAIHA (log-rank test: p = 0.003). Subgroup analyses showed no significant difference in risk of death between long-term and short-term OCS users; however, in the sensitivity analysis, long-term OCS users showed significantly higher risk of death (adjusted hazard ratio: 1.45; 95% confidence interval: 1.180, 1.781; p < 0.001) versus short-term OCS users.

Conclusion: Secondary wAIHA or long-term OCS use was associated with lower OS, underscoring the disease burden and unmet need for efficacious wAIHA treatments.