Prevalence of sickle cell trait and sickle cell disease among African American live births in Shelby Co., TN

Accurate regional quantification of sickle cell disease (SCD) and sickle cell trait (SCT) in the U.S. could aid public health officials and clinicians to better allocate and prioritize resources. The CDC estimates SCD and SCT at 1/500 and 1/12 African American (AA) live births and multiple sources suggest SCD rates could be as high as 1/350. From statewide newborn screening, positive tests for hemoglobinopathies in Shelby County Tennessee are reported to St. Jude Children's Research Hospital in Memphis. Using data from 2002-2010, we estimated the prevalence of SCD and SCT and compared rates to the national averages. In Shelby County, SCT was found in 5,146/75,784 AA live births and SCD in 267/75,784. The SCT prevalence was 67.9 (95% CI: 66.1-69.7)/1000 AA births, approximately 1/14.7. That rate for SCT is lower than the nationally reported 1/12 live births (p-value<0.001). The prevalence of SCD was 3.5 (95% CI: 3.1-4.0)/1000 AA live births or 1/286 (60% HbSS/Sβ⁰ thalassemia), which is higher than the national estimate of 1/350 (p-value<0.001). Our SCT findings were similar to those of a California study that found 1/14 AA births but our SCD rates differed from the 1/396 (57% HbSS/Sβ⁰ thalassemia) found in the same California study. Recent Shelby County rates of SCD and SCT differ substantially from national averages with higher than expected SCD and lower than expected SCT rates, warranting further investigation. We have demonstrated that variation in SCD and SCT rates exists in the U.S. and suggest that regional studies would better inform screening, education, and health care resource allocation.