Creating an Automated Contemporaneous Cohort in Sickle Cell Anemia to Predict Survival After Disease-Modifying Therapy.

For participants receiving experimental gene therapy or gene editing clinical trials, the FDA requires contemporaneous controls to compare clinical outcomes. However, developing a contemporaneous cohort of rare diseases is costly and requires multiple person-hours. In a single referral center for sickle cell disease, we tested the hypothesis that we could create an automated contemporaneous cohort of children and adults with sickle cell anemia (SCA) to predict mortality. Data were obtained between 1/1/2004 and 4/30/2021. We identified 419 individuals with SCA with consistent medical care (i.e., followed continuously for >0.5 years with no visit gaps ≥3.0 years). The median age was 10.2 years (IQR 1.0 - 24.0 years), with a median follow-up of 7.4 years (IQR 3.6-13.5 years) and 47 deaths. A total of 98% (274 of 277) of the children remained alive at 18 years of age, and 34.3% (94 of 274) of those children were followed into adulthood. For adults, the median age of survival was 49.3 years of age. Treatment groups were mutually exclusive and in a hierarchical order: hematopoietic stem cell transplant (n=22)>regular blood transfusion for at least two years (n=56)>hydroxyurea for at least one year (n=243)>no disease-modifying therapy (n=98). Compared to those receiving no disease-modifying treatment, those treated with hydroxyurea therapy had significantly lower hazard of mortality (hazard ratio=0.38, p=0.016), but no statistical difference for those receiving regular blood transfusions compared to no disease-modifying therapy (hazard ratio=0.71, p=0.440). An automated contemporaneous SCA cohort can be generated to estimate mortality in children and adults with SCA.