Sickle Cell Disease Prevalence, Social Vulnerability, and Rural-Urban Commuting Area: A National Snapshot from Electronic Medical Data

Introduction:

The Centers for Disease Control (CDC) currently estimates the prevalence of sickle cell disease at 100,000 people in the United States, who predominantly self-identify as Black. However, the CDC also states that it is not known what the true prevalence of sickle cell disease is. Furthermore, important data on age distribution, social vulnerability, and the concentration of rural and urban residency in sickle cell disease is lacking. Data on age distribution, social vulnerability and rural-urban commuting could contribute to our understanding of the excessive burden of comorbidities that has been described in sickle cell disease in various cohorts. The purpose of this study was to capture, in real time, the prevalence of these demographic and socioeconomic characteristics in sickle cell disease using a national database of electronic medical records from various health systems in 50 states in the United States.

Methods:

This cross-sectional cohort study used electronic medical records of inpatient and outpatient visits from Epic's Cosmos. Epic's Cosmos integrates electronic medical records from 259 million patients across 35,412 clinics and 289,920 hospital beds in 50 states in the United States. We included living patients as of July 10, 2024, with sickle cell disease as an active problem list diagnosis defined by the SNOMED-CT concept “Sickling disorder due to hemoglobin S” (417357006), which excludes concepts defining sickle cell trait. We extracted the following patient characteristics: age, sex, race, ethnicity, state of residence, Rural-Urban Commuting Area (RUCA) codes, and social vulnerability indices (SVI). Subsequently, SVI was divided into quartiles: low (0 ≤ SVI ≤ 0.25), medium (0.25 < SVI ≤ 0.5), high (0.5 < SVI ≤ 0.75), and very high (0.75 < SVI ≤ 1.0) vulnerability.

Results

As of July 10, 2024, we identified 38,897 patients with sickle cell disease. The median (IQR) age was 28 (16 - 39) years, with 28% under 18 years and only 3% over 65 years. Women represented 54% of the cohort. Ninety-five percent identified as Black or multiple races and 4% reported Hispanic ethnicity. The most common states of residence were Florida (12%), Texas (11%), and Georgia (9%). Illinois, Louisiana, Mississippi, North Carolina, New York, Ohio, Pennsylvania, and Virginia each constituted between 4 to 5% of the cohort states of residence. A RUCA score of 1, indicating highly urban residence, was reported in 88% of patients. The median (IQR) SVI was 0.83 (0.61 to 0.94). Most patients lived in zip codes with very high (61%) or high (22%) SVIs. Only 5% of patients lived in low SVI zip codes.

Conclusion

We identified nearly 40% of the presumed 100,000 sickle cell disease patients living in the United States today utilizing Epic's Cosmos database. This represents one of the largest descriptive studies of patients with sickle cell disease to date, providing a critical modern snapshot of the current state of this population. Our analysis confirms the common belief that patients with sickle cell disease tend to be young and concentrated in urban areas. It is unclear whether this concentration in urban areas is due to a need for better access to specialized care. We observed significant social vulnerability, which may contribute to adverse medical outcomes. Further research is needed to determine the prevalence of sickle cell disease in the United States, how urbanization contributes to SVI in this population, and the role of SVI/RUCA in adverse clinical and patient reported outcomes previously reported in this population.

No relevant conflicts of interest to declare.