Alloimmunization in myelodysplastic syndrome is associated with higher healthcare costs, longer hospitalizations, and increased mortality.

Background: Transfusion of red blood cells (RBC) is an important component of treatment for myelodysplastic syndromes (MDS). Patients receiving frequent transfusions are more likely to develop alloimmunization, an immune reaction to minor RBC antigens that increases the risk of complications including delayed hemolysis. Phenotypic matching is believed to reduce alloimmunization although rigorous evidence is lacking. This study examines the association of alloimmunization with clinical and economic outcomes and may give insight into the potential benefit of phenotypic matching in MDS.

Study design and methods: This study used data from 1054 hospitals included in the Premier hospital chargemaster dataset. Alloimmunized MDS patients (January 2015 to June 2019) were indirectly identified by ICD-10 codes (antiglobulin crossmatch and RBC antibody identification). The primary objective was assessment of the association between incremental cost per patient encounter and alloimmunization in MDS patients. Secondary objectives were assessment of the association of length of stay, intensive care unit (ICU) admission, and inpatient mortality for alloimmunized versus non-alloimmunized MDS patients.

Results: Worse clinical and economic outcomes were observed for the alloimmunized group. Higher costs (14%), more ICU admissions (38%), longer hospital (21%) and ICU stays (55%), and greater mortality (30%) were observed among alloimmunized MDS patients compared to non-alloimmunized (p < .0001 for all comparisons).

Discussion: Alloimmunization may be associated with higher costs and greater risk of ICU admission and death in patients with MDS. While further mechanistic research is needed, it seems that MDS patients may benefit substantially from practices that limit risk of alloimmunization, including providing prophylactic antigen matching.