Covington, Mischa L.

ABSTRACT Prior surveys of chronic automated red blood cell exchange (RCE) for patients with sickle cell disease (SCD) have identified considerable procedural variability, especially with the use of isovolemic hemodilution red blood cell exchange (IHD‐RCE). We conducted a survey of chronic RCE practices among American Society for Apheresis (ASFA) members to identify opportunities for practice harmonization and future studies. The ASFA SCD Research Subcommittee developed a 72‐item survey of chronic RCE practices, with a focus on IHD‐RCE. The survey was validated internally and distributed by email to all ASFA members from September 2024 to February 2025. One survey response from each institution was retained for data analysis. Descriptive statistics were performed. Sixty‐two survey responses, including three from international institutions, were retained for analysis. Sixty‐one percent of respondents (38/62) reported using at least one fixed RCE target, with end hematocrit being the most common fixed parameter (40%, 25/62), followed by fraction of cells remaining (31%, 19/62) and hemoglobin S% (27%, 17/62). Most respondents (60%, 37/61) performed IHD‐RCE at their institution, though other details such as the minimum hematocrit, exclusion criteria, and response to adverse effects were variable. Consistent pre‐ and post‐RCE laboratory monitoring practices were reported. Consistent with earlier surveys, procedural variability in chronic RCE practices for patients with SCD is observed. This highlights opportunities to compare outcomes where practice variability exists. Consensus guidelines based on institutional practices with optimal outcomes should be developed.

Abstract Background Red cell alloimmunization complicates sickle cell disease (SCD) management despite current widespread prophylactic Rh/K matching in the United States (US). Regional antibody patterns remain poorly characterized. Study Design and Methods We conducted a retrospective analysis of 2965 SCD patients from 9 US sites (2010–2022). All hospitals prophylactically match for Rh and K antigens. Each site collected demographics, antigen status, antibody histories, and antibody screen results from their laboratory information system. Results Overall antibody prevalence was 29.7% with dramatic institutional variation (17.9%–56.0%). Alloantibody prevalence was 27.5%. Most autoantibody‐positive patients (74.23%) also had alloantibodies, identifying a high‐risk population. A third of patients with positive antibody histories had negative screens. Pediatric patients showed markedly different antibody profiles than adults. Hospitals’ antibody patterns clustered by patient age rather than geography. Rh and K antibodies were the most common and also most likely to co‐occur, followed by S, Fya, and Jkb antibodies. Antibodies against Jsa (1.82%), V (1.75%), and Kpa (1.69%) were more prevalent than anti‐Jka (1.28%). Despite regional antibody variation, antigen frequencies remained overall consistent. In antigen–antibody pairwise comparisons, 3.15% were antigen‐negative and antibody‐positive reflecting alloimmunization; 0.47% were both antibody‐ and antigen‐positive, suggesting partial/variant antigens. Discussion Substantial institutional variation in antibody prevalence suggests need for site‐specific approaches to testing and prophylactic matching. High co‐occurrence of auto‐ and alloantibodies, antibody immunogenicity patterns, and antigen–antibody discordances support the need for further research and consideration of refined testing and/or matching strategies beyond the current Rh and K standard.

ABSTRACT A major challenge in hematopoietic progenitor cell apheresis is determining the whole blood (WB) volume to process to achieve a CD34+ cell collection goal. We developed a web‐based calculator app that uses the Collection Efficiency 2 (CE2) model to estimate personalized WB processing volumes needed to reach a prescribed CD34+ cell collection goal. Retrospective evaluation of the app using collection data from two academic medical centers showed that actual processed WB volumes were frequently higher than the app's recommendations. The frequency of potential under‐collection events is predicted to be low had the app‐calculated volumes been utilized. Our findings suggest that using the app's recommendations may lower total WB processing volumes, reducing over‐collection and time spent on the apheresis machine, while maintaining a low under‐collection risk profile.