Comparison of chronic transfusion volume protocols for children with sickle cell anemia

Background: Chronic transfusion therapy (CTT) for sickle cell anemia (SCA) reduces the risk of stroke by diluting hemoglobin S (HbS) with HbA red blood cells and suppressing erythropoiesis. The goal of a CTT regimen is to maintain pre-transfusion HbS <30% while avoiding hyperviscosity; however established protocols for transfusion volumes are lacking. Objectives: To compare HbS, reticulocytosis, and total blood transfusion volumes between 2 CTT protocols that use higher vs. lower transfusion volume parameters for pediatric SCA patients. Results: There were 82 patients (63 HV, 19 LV protocol, 1 LV/HV) who were followed for 1042 transfusion episodes. Excluding 167 PME and transfusions with TI >40 days, there were 571 HV and 205 LV transfusions. For HV transfusions, there was higher mean transfusion volume (13.3 vs. 12.1 ml/kg, p<0.0001), longer TI (29.9 vs. 27.7 days, p<0.0001), higher Hb (9.74 vs. 9.38 g/dL, p<0.0001), but higher mean HbS (22.4 vs. 20.6%, p=0.034). There was no significant difference in reticulocytes (9.64 vs. 9.09%, p=0.11) or frequency of HbS >30% (21.5% of HV vs. 17.1% of LV transfusions, p=0.18). Including all transfusions, the mean total blood volume per 365 days was 172.4 ml/kg for HV and 168.6 ml/kg for LV transfusions (p=0.58). Conclusion: The HV transfusion protocol allowed higher Hb and did not increase the total blood volume received per year; however HbS suppression was greater with the LV protocol. This study did not examine hyperviscosity, which may be a potential concern with higher transfusion volumes. Abstract source