(P-TA-1) A Large, International Survey of Apheresis Providers’ Transfusion Thresholds in the Peri-therapeutic Apheresis Period

A 10-question survey (SurveyMonkey, San Mateo, CA) was designed, beta tested, and piloted for user time requirement, question clarity, and software functionality. The survey was sent to all members of AABB’s Therapeutic Apheresis Subsection (n=459) with biweekly reminder emails. Redistribution was permitted. The calculated sample size (survey responses) for 95% confidence level with a 10% margin of error was n=80. Response/non-response was analyzed.

Results/Findings: Response rate was 11% (51/459). Most respondents were pathologists (42/48, 87.5%) at academic medical centers (37/48, 77.1%). Over half of respondents perform apheresis procedures on both adult and pediatric patients (31/48, 64.6%). The most frequently selected RBC threshold, regardless of clinical setting, was 7g/dL.  A RBC prime was preferred (first choice of 15/27, 55.6%) for an extracorporeal volume of >15% (16/25, 64.0%). The most or equally-most frequently selected platelet threshold was 50K/uL, except in therapeutic plasma exchange (TPE) for thrombotic thrombocytopenic purpura (TTP) or peripheral blood stem/mononuclear cell collection [Table 1]. For TTP, 8 (30.8%) respondents performed TPE in patients with platelets ≤5 or 10K/uL, while 7 (26.9%) performed TPE only with higher counts (≤20, 30, or 50K/μL). For pre-procedure central line placement, 10 (38.5%) preferred platelets of 20K/μL, 6 (23.1%) 50K/μL, and 3 (11.5%) 100K/μL. For platelet transfusion timing, no clear preference among pre-, intra-, and post-TPE was noted. Platelet transfusion through the TPE circuit in lieu of a portion of replacement fluid was rare (3/30, 10%). For therapeutic plateletpheresis of asymptomatic thrombocytosis, 9 (33.3%) respondents would perform apheresis at >1M platelets/uL and 11 (40.7%) would not perform this procedure at any platelet count. For thrombocytosis with active bleeding or clotting, 18 (66.7%) would cytapherese at a platelet count >500K/uL or >1M.

Conclusions:

This large international survey of transfusion thresholds in the peri-therapeutic apheresis period showed that RBC thresholds were similar to and platelet thresholds often higher than transfusion guidelines. The limitations include a response rate below the target sample size, so responses highlight themes and outliers and are not broadly generalizable.  Because survey redistribution was permitted, the true response rate cannot be determined.  The results of this survey suggest that a majority of responding apheresis providers attempt to follow published transfusion threshold guidelines.  Practice varies in situations not specifically addressed by guidelines.