Oral Abstract
Immunohematology and Genetic Testing (red cells/leukocytes and platelets) - Immunohematology (includes serology)
Mischa Covington, MD, PhD
Brigham and Women's Hospital
Brookline, Massachusetts
Disclosure information not submitted.
Red blood cell (RBC) antibodies complicate the care of patients with sickle cell disease (SCD). Prophylactic Rh and K matching has reduced alloimmunization rates, but the risk remains. In the era of prophylactic matching, it is unclear whether there are regional differences in patient antibody prevalence or antigen frequency. This study examines RBC antibody prevalence and antigen frequency in patients with SCD from 10 hospitals across different geographic regions in the United States (US).
Study
Design/Methods:
Retrospective data from 01/2010 to 02/2022 was collected on patients with SCD at 10 US sites. All hospitals prophylactically match for the D, C, E, c, e, and K antigens. Four of the 10 hospitals treat pediatric patients ( < 18 years) in addition to adults. The following data was gathered for each patient: adult ( >=18 years old) or pediatric, sex, ABO/RhD type, antigen status for C/c, E/e, K, Fya/Fyb, Jka/Jkb, M/N and S/s (determined by either serology or genotyping, if available), all antibodies (historical and current) and presence of autoantibodies. Descriptive statistics and nonparametric ANOVA analysis (Friedman test) were used.
Results/Findings:
Antibody prevalence varied substantially between hospitals (range 18% - 93%), with overall prevalence of 31% across all sites. Patients in the southern US had lower antibody prevalence (26.1 – 29.3%) compared to the north (30.1 – 47.6%), except for northern hospitals with significant pediatric populations (17.9%, 22.7%). Patients in the northeast had the lowest prevalence of autoantibodies (2.1 – 7.1%, Fig. 1A). In contrast to antibody prevalence, patient antigen frequencies were essentially the same across regions (p = 0.46, Fig. 1B). Among all patients, the most common antibodies were anti-E (10.5%), anti-C (8.1%), anti-K (6.2%), anti-S (6.1%), anti-Fya (4.6%), and anti-Jkb (4.4%). Alloimmunization was also common for anti-D (2.6%), anti-Jsa (2.1%), anti-V (1.9%), anti-Kpa (1.8%), and anti-Cw (1.32%), more than for anti-Jka (1.29%). The prevalence of anti-M and warm autoantibodies (WAA) did not vary by age nor sex. The most prevalent antibodies among pediatric patients were anti-M (4.3%), WAA (2.9%), anti-C (1.8%), anti-E (1.7%), anti-Jkb (1.4%), anti-S (1.4%), and anti-D (1.3%) (Fig. 1C).
Conclusions:
Our multi-center analysis reveals significant demographic and geographic variations in RBC antibody prevalence among patients with SCD, in contrast to consistent antigen frequencies across regions. There are several common antibodies against low-prevalence antigens which may be missed on antibody screens resulting in electronic crossmatch compatibility and issuance of incompatible blood. These findings support considering demographics and institution-specific alloimmunization patterns when developing protocols for prophylactic phenotype-matching and pre-transfusion testing (e.g., crossmatch method, screening cells) for patients with SCD.