High Mortality Among Children with Sickle Cell Anemia and Stroke Who Discontinue Chronic Blood Transfusion After Transition to An Adult Program
Authors: Ballas Samir K. 
Published: October 2019

Abstract
Abstract 1629

Introduction:
The Comprehensive Sickle Cell Disease study (CSCD) of 4082 patients showed that the likelihood of developing stroke was 11% by the age of 20 years for patients with sickle cell anemia (SS).The stroke prevention trials (STOP I and STOP II) in SS showed that blood transfusion prevents the occurrence of primary stroke in children with abnormal TransCranial Doppler (TCD) velocities (STOP1) and discontinuation of transfusions after 30 months resulted in a high rate of reversion to abnormal TCD velocities and stroke (STOP II). To that end all children with abnormal TCD velocities are managed with chronic blood transfusion without interruption as long as they are in pediatrics. The problem arises when they are due to be transferred to adult care after the age of 18 years. The transition process from pediatrics to adult programs is marred with several issues that often result in interruption or discontinuation of the quality care the patients had as children. There is little or no information in the literature about the outcome of children with stroke after transition to adult programs. In this study we report the outcome of 22 patients, 10 males and 12 females, with SS and stroke who were referred to our adult program from several Children's hospitals between 1993 and 2009.

Patients & Methods:
Records were kept prospectively. The mean age of patients at transition was 22.4 ± 3.10 years. Blood bank data were performed and computerized according to FDA and AABB regulations. Blood counts and % Hb S were done before and after each transfusion. Hb S was kept below 30% or 50% after transfusion. Metabolic profiles were done every 6 months or more often if needed. Molecular diagnostics including alpha genotypes and beta globin haplotypes were done by described methods. Statistical analysis was by the 2-tailed t test.

Results:
All patients had ischemic strokes during childhood and one had hemorrhagic stroke superimposed on cerebral infarction. Two patients developed moyamoya after transition. No alpha gene deletion was detected in 18 patients, 4 had one alpha gene deletion and none had 2 alpha gene deletion. The Ben/CAR haplotype was found in 7 patients, Ben/Ben in 5, Ben/Sen in 4 and other combinations in 6 patients; 21 patients were heterozygous for the Ben haplotype. Hb F was 1.0–7.0% except for one patient on hydroxyurea (HU) with 20% Hb F. All patients were kept on the same regimen of transfusion they had as children; 15 were kept on exchange transfusion two of whom were non-compliant, two were kept on simple transfusion plus HU and the remaining 5 patients refused to have chronic blood transfusion and were kept on normal care. Some of the causes for refusal were due to alloimmunization and difficult venous access. One of these 5 patients agreed to be on HU. Patients on blood exchange required an average of 55 ± 13.5 (40-98) units of RBC annually. Those on simple transfusion required up to 24 units annually. Alloimmunization was present in 10 patients with the number of alloantibodies between 1 and 6 per patient. The most common alloantibodies were ant-E and anti-K. Patients who were compliant with blood transfusion were rarely hospitalized for painful crises. Patients who were noncompliant with blood transfusion or who refused to be maintained on chronic transfusion were hospitalized for painful crises 5.7 ± 5.00 times annually (p<.025). All 5 patients who refused to be maintained on chronic blood transfusion died within 3 years after transition. Cause of death was massive intraventricular hemorrhage in one patient proven by autopsy, massive hemispheric infarct proven by imaging in the second patient leading to coma and death in the hospital and sudden death during hospitalization for painful crises in the remaining 3 patients. Two patients who were not compliant with chronic blood transfusion died within 2 years after transition due to ARDS. Thus the overall rate of death after transition was 32% and the major cause was discontinuation of chronic blood transfusion. The mean age at death was 27.0 ± 3.16 years whereas the mean age of patients who are alive is 35.4 ± 5.92 years (p<.001).

Conclusion:
Our data indicate that about one third of patients with SS and stroke die within 3 years after transition especially if chronic blood transfusion is discontinued or if compliance was poor. It is imperative that all efforts should be made to maintain adequate chronic blood transfusion for children with SCD and stroke after transition to adult care.

Disclosures:
No relevant conflicts of interest to declare.