Using stored electronic health record data is feasible and efficient means for creating an automated contemporaneous cohort to estimate survival following disease-modifying treatment in children and adults with sickle cell anemia (SCA), according to research published in Blood Advances.

“[Clinical] data warehouses contain clinical information from multiple years of medical records. Using clinical and laboratory data in a warehouse for creating a cohort of a rare genetic disease is emerging as a reasonable alternative to determine the clinical history of a rare disease,” the study authors explained in their report.

Researchers at a referral center for sickle cell disease hypothesis that they could create an automated contemporaneous cohort of children and adults with SCA to predict mortality across different disease-modifying treatment options. They obtained electronic health record data from January 1, 2004, to April 30, 2021, from a university medical center clinical data warehouse.

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The team identified 419 patients with SCA who had received consistent medical care (defined as continuous follow up for >0.5 years with no visit gaps greater than 3.0 years). The median age of the patients was 10.2 years (interquartile range [IQR], 1-24 years). The median follow-up duration was 7.4 years (IQR, 3.6-13.5 years), with 47 deaths.

For children, 98% (274/277) remained alive at 18 years of age, with 34.3% (94/274) of those followed into adulthood. For adults, the median age of survival was 49.3 years (95% CI, 42.9-54.9 years).

The researchers constructed Kaplan-Meier curves to evaluate the different treatments, with the highest proportion of surviving patients having received hematopoietic stem cell transplant, followed by regular blood transfusion for at least 2 years, hydroxyurea for at least 1 year, and no disease-modifying therapy.

The study also demonstrated that patients treated with hydroxyurea had a significantly lower hazard of mortality compared to those receiving no disease-modifying treatment (hazard ratio [HR], 0.38; P =.016). No significant difference was observed between those receiving regular blood transfusions and those receiving no disease-modifying therapy (HR, 0.71; P =.440).

“Traditionally, creating contemporaneous cohorts has been done through manually curated SCA registries; however, these registries are expensive to initiate and even more challenging to maintain,” stated the study authors. “We were able to pull the clinical information over 17 years from a large health care system which includes multiple hospitals. Other individuals in small or large health care systems may be able to replicate or extend our tools to mimic our approach for assessment of mortality rate of their institution in their health care system.”

Limitations of the study included lack of confirmation of adherence to hydroxyurea therapy, an inability to account for prescriptions from outside centers, fragmentation of care/irregular follow-up visits, and an inability to evaluate the impact of recent FDA-approved drugs.


Cronin RM, Wuichet K, Ghafuri DL, et al. Creating an automated contemporaneous cohort in sickle cell anemia to predict survival after disease-modifying therapy. Blood Adv. 2023;7(15):3775-3782. doi:10.1182/bloodadvances.2022008692