(P-TA-4) Chronic Automated Red Cell Exchange Therapy for Sickle Cell Disease: A Tertiary Center Decade-Long Experience

Background/Case Studies: Automated red cell exchange (RCE) is a major treatment for sickle cell disease (SCD), particularly for acute complications, such as stroke and severe acute chest syndrome. RCE is also an important chronic transfusion therapy (CTT) with diverse indications such as stroke prophylaxis and pregnancy. However, the evidence for the use of chronic RCE for certain indications is limited, especially in adults, and the optimal role is not clearly defined.

Study

Design/Methods: A retrospective evaluation was conducted of SCD patients referred for chronic RCE at our institution from 1/2010 to 12/2020. Data that were extracted from medical records included patient demographics, referral indications, procedural details (e.g., vascular access, number of procedures, and adverse events, including infection, thrombosis, and alloimmunization). A subanalysis was performed of patients who were adherent to chronic RCE for 3 years, comparing the number of annual acute care encounters while on therapy to the year preceding their first RCE.

Results/Findings: A total of 164 patients were identified. Mean age was 30.4 years (range 7-62) at referral, 27 patients (16.4%) were ≤20 years of age, and 99 (60%) were females. Of 164, 5 patients (3%) were referred but did not undergo any procedures; 70 (42.6%) were CTT naïve prior to referral. Of patients who were previously receiving non-RCE CTT, leading indications for non-RCE CTT were recurrent pain crisis (41/94, 44%) and neurologic complications (39/94, 41%); the leading indications for chronic RCE referral were refractory pain (73/164, 45%) and iron overload (59/164, 36%). A total of 5,090 procedures occurred during the study period (mean of 31 procedures per patient, range 0-136). Most procedures were performed via central vascular access; 13% of patients (21/164) underwent RCE using peripheral vascular access only (mean 21 procedures: range 1-105). Of patients who had a central vascular access, 8/138 (6%) had ≥1 central line-related thrombosis, and 16/138 (12%) had ≥1 central line-related infection. Of patients who started chronic RCE without RBC alloimmunization, 12/105 (11.4%) developed new antibodies during chronic RCE (of note, patients were not prophylactically matched for C, E, K1 in keeping with institutional practice). In patients who were adherent to therapy for 3 years, no significant difference was detected in acute care encounters following initiation of treatment (Table 1).

Conclusions: Chronic RCE is a feasible and generally well tolerated CTT for SCD patients. Major complications pertain to central vascular access; our findings demonstrate the feasibility of long term chronic RCE without a central line. The findings underscore the need for prospective clinical trials to identify those patients who are most likely to benefit from chronic RCE and refine selection accordingly.

Importance of research: Our study describes a large population of SCD patients on chronic RCE in the United States. We report the feasibility of this therapy as a long-term option, yet with certain possible complications, mostly central line related. We did not observe a significant change of acute care visits over time; while acknowledging the limitations of our study, this highlights the need for prospective trials, especially in adults, to examine the optimal role of chronic RCE in patients with SCD.