Incidence and risk factors of relapses in idiopathic autoimmune hemolytic anemia

Patients with idiopathic autoimmune hemolytic anemia (AIHA) of warm antibody type usually respond to corticosteroid therapy. However a proportion of patients will have disease relapse after steroid-induced remission.

To assess the incidence and the possible risk factors of the relapse in a cohort of patients with idiopathic AIHA.

We conducted a retrospective and prospective study of 34 idiopathic AIHA patients regularly followed at the Division of Hematology during January 1973 to December 2006. The medical records were reviewed for active hemolytic events and relapses, episodes of infections, pattern of corticosteroids administration and tapering. Types and subtypes of autoantibodies were studied by column agglutination test (the "gel test").

One patient with cold agglutinin disease was excluded, leaving a total of 33 patients (24 with warm type, 9 with mixed warm and cold type AIHA) in the study. The incidence of relapse was 1.157 episodes/person/year. The mean duration of relapse after remission was 23 months. Episodes of recurrent hemolysis were more frequent when corticosteroid administration was tapered from high to low dose (10 mg/day of prednisolone) within two months compared with a longer than two-month tapering (38 vs. 11 episodes; p < 0.01). In addition patients receiving continuing low dose of corticosteroids (< or = 10 mg/day of prednisolone) for > 6 months had lower incidence of relapse and longer duration of remission than those with discontinuing the medication within 6 months (0.443 vs. 1.911 episodes/person/year, p < 0.01; 37.4 vs. 10.6 months, p < 0.01). Episodes of recurrent hemolysis were more frequently observed in patients with events of infection than those without infections (mean 7.69 vs. 2.81, p = 0.032). Types and subtypes of autoantibodies did not seem to influence relapse in AIHA.

Short duration of maintenance and rapid tapering of corticosteroids and infections are possible risk factors of relapses/recurrent hemolysis in idiopathic AIHA.