Association between Sickle Cell Trait with Selected Chronic Medical Conditions in U.S. Service Members

Introduction: Sickle cell trait (SCT), the heterozygous carrier state for hemoglobin S, is present in an estimated 1.6% of all newborns and 7.3% in black individuals in the USA. SCT has long been considered a benign condition with anticipated normal life expectancy and no increased risk for chronic diseases. The medical literature is inconclusive on the potential association between SCT and chronic medical conditions (CMC) including chronic kidney disease, venous thromboembolism, and stroke. Studies addressing these questions are lacking particularly in non-Black young adults. Materials and Methods: We conducted a retrospective cohort study among U.S. active duty, enlisted, service members who entered from 1992 to 2012 using existing Department of Defense (DoD Military Healthcare System databases). SCT positive subjects (1,323) were matched by demographic characteristics to SCT negative subjects (3,136) and followed through 2013 for CMC that included deep vein thrombosis, diabetes mellitus and hematologic, pulmonary, and renal conditions. Results: The rate of developing any of the included CMC was higher for those with SCT (incidence rate ratio = 1.71 95% CI 1.61-1.81) compared with those who were SCT negative and their healthcare utilization rate for any of CMC studied was higher for SCT positive compared with negative individuals (URR = 2.45 95% CI 2.41-2.50), with the highest rate ratios observed for hematologic and renal conditions. SCT positive compared with negative individuals were more likely to have encounter diagnoses of sickle cell disease and diabetes Type II and were less likely to have encounter diagnoses of other hemoglobinopathies and diabetes type I. Conclusion: SCT in these racially diverse, young adults increased both the incidence of and healthcare utilization for thromboembolism, diabetes mellitus type II, sickle cell disease, pulmonary, and chronic renal conditions. These findings suggest that clinicians treating young adults with SCT should exercise heightened surveillance for these CMC to ensure both early diagnosis and access to treatments.