Chronic Manual Exchange Transfusions Compared with Erythrocytapheresis in Children and Teens with Sickle Cell Disease
Authors: Woods Debbie , Hayashi Robert J. , Fields Melanie E. , Hulbert Monica L. 
Published: October 2019

Abstract
Background:
Children and young adults with sickle cell disease (SCD) are at high risk of strokes and are frequently treated with red blood cell (RBC) transfusions. RBCs may be given by simple transfusion, manual exchange transfusion (ME), or erythrocytapheresis (ECP) with a goal of suppressing hemoglobin (Hb) S while minimizing transfusion-induced iron overload. There have been no formal comparisons of these modalities, and practices for transfusion management vary among institutions. We compared transfusion therapy outcomes among patients with SCD undergoing transfusion therapy for primary or secondary stroke prevention, hypothesizing that children would be more likely to achieve Hb S suppression and ferritin goals while receiving ECP. We also compared complications of transfusion therapy across transfusion modalities.
Methods:
This is a single-institution retrospective cohort study of 38 patients with SCD who received chronic transfusion therapy for primary or secondary stroke prevention from 1/1/2008 through 12/31/2012. Per institutional practice, younger patients receive ME for stroke prevention; they are offered ECP when their size is adequate for a large-bore double-lumen implantable port, but may choose to continue ME. The pre-transfusion Hb S goal is <30% for at least 2 years, then may be liberalized to <50% for subjects without either abnormal transcranial Doppler ultrasound or infarct recurrence. Hb S percentage and ferritin were measured prior to each transfusion. Patients on transfusion therapy for 6 or more months were included; one child who had a stroke after brain tumor biopsy was excluded. Subjects were censored at last date of follow-up or date of hematopoietic stem cell transplant. The following factors were evaluated: duration and mode of transfusion therapy, achievement of Hb S suppression goal, ferritin levels, and catheter complications. Categorical variables were compared with Fisher’s exact test and medians with the Mann-Whitney U-test in SPSS version 21 (IBM, Armonk, NY).
Results:
During the study period, 38 subjects (42% male) met all inclusion criteria. Of these, 5 received exclusively ECP, 17 received exclusively ME, and 16 received both modalities during the study period. For the most recent 12-month period of data for each participant, 13 received ECP and 25 received ME. There was no association between modality of transfusion and the proportion of visits during which subjects achieved their pre-transfusion Hb S goal during the 12-month period. The median proportion of visits achieving the Hb S goal was 0.80 for ECP (IQR 0.40-1.0) versus 0.50 for ME (IQR 0.28-0.90) (p=0.27). Furthermore, there was no significant difference in ferritin concentrations between transfusion modalities: median 875 ng/ml for ECP (IQR 578-2659) versus median 1527 ng/ml for ME (IQR 731-2568) (p=0.56).
Children who had ever received ECP had a significantly longer total duration of transfusion therapy (median 97 months, IQR 51.5-134) than those receiving ME only (median 28 months, IQR 12.5-47) (p<0.001). Among 21 subjects who had ever received ECP, 15 (71.4%) experienced one or more catheter complications, including infection, thrombosis, catheter leakage, or venous stenosis, compared with 1/17 subjects (5.8%) who had never received ECP (OR for catheter complications 40 for subjects who had ever received ECP, 95% CI 4.29, 372.4, p <0.001). Five subjects switched from ECP to ME due to stenosis of the great vessels that precluded double-lumen port replacement.
Conclusions:
Children with SCD receiving ECP and ME for stroke prevention in this cohort had similar achievement of Hb S suppression goals and iron overload management. Additional patient-specific factors may be responsible for variations in pre-transfusion Hb S and ferritin concentrations. Catheter complications were significantly more common in children and adolescents receiving ECP compared with ME, likely due to the large-bore double-lumen port utilized for ECP at our center.

Disclosures
No relevant conflicts of interest to declare.