Risk factor analysis of autoimmune hemolytic anemia after allogeneic hematopoietic stem cell transplantation in children

Autoimmune hemolytic anemia (AIHA) is a clinically relevant complication after allogeneic hematopoietic stem cell transplantation (HSCT). Currently, there is no established consensus regarding the optimal therapeutic approach. Whether AIHA contributes to increased mortality is still somewhat controversial. We investigated the incidence, risk factors, and outcome of post-transplant AIHA in 265 consecutive pediatric patients undergoing allo-HSCT over a 17-year period. Onset of AIHA was calculated from the first documented detection of AIHA by either clinical symptoms or positive direct agglutinin test. Resolution of AIHA was defined as normalization of hemoglobin and biochemical markers of hemolysis with sustained transfusion independence. We identified 15 cases of AIHA after allo-HSCT (incidence rate, 6%). Ten (67%) of these patients had a positive direct antiglobulin test. Data were obtained for 9 boys and 6 girls after a median follow-up of 53 months (range 4-102). The median age was 5.1 years (range 0.5-15.4) at the time of HSCT and the median time to emergence was 149 days (range 42-273). No significant risk factor for post-transplant AIHA has emerged from our data to date. In the majority (14 of 15; 93%) of AIHA patients, multiple agents for treatment were required, with 12 of 15 (80%) patients achieving complete resolution of AIHA. No splenectomy was performed in any of our patients. For various reasons, post-transplantation AIHA poses an extraordinary challenge to transplant physicians. Despite the advancements in diagnostic tools, therapeutic challenges remain due to the myriad interacting pathways in AIHA.