Association between baseline fetal hemoglobin levels and incidence of severe vaso-occlusive pain episodes in children with sickle cell anemia

The ameliorating effect of high fetal hemoglobin (HbF) levels on the incidence of pain episodes in sickle cell anemia (SCA) is well known; however, this relationship in children with SCA is less clearly established. We tested the hypothesis that higher HbF levels in children with SCA are associated with decreased incidence of severe pain episodes, defined as an event requiring hospitalization. Based on a uniform definition of severe pain in two cohorts, a meta-analysis was performed using data from the Silent Infarct Transfusion (SIT) Trial (n= 456) and the Cooperative Study of Sickle Cell Disease (CSSCD) (n=764). Baseline HbF levels were associated with the incidence of severe pain (P-value=0.02). Hospitalization for pain is a viable SCA endo-phenotype for future study.