Association among sickle cell trait, fitness, and cardiovascular risk factors in CARDIA

Abstract

Key Points• SCT status is not significantly associated with longitudinal changes in fitness among African Americans.• SCT status is not an independent risk factor for hypertension, diabetes, or metabolic syndrome among African Americans.The contribution of sickle cell trait (SCT) to racial disparities in cardiopulmonary fitness is not known, despite concerns that SCT is associated with exertion-related sudden death. We evaluated the association of SCT status with cross-sectional and longitudinal changes in fitness and risk for hypertension, diabetes, and metabolic syndrome over the course of 25 years among 1995 African Americans (56% women, 18-30 years old) in the Coronary Artery Risk Development in Young Adults (CARDIA) study. Overall, the prevalence of SCT was 6.8% (136/1995) in CARDIA, and over the course of 25 years, 46% (738/1590), 18% (288/1631), and 40% (645/1,611) of all participants developed hypertension, diabetes, and metabolic syndrome, respectively. Compared with participants without SCT, participants with SCT had similar baseline measures of fitness in cross-section, including exercise duration (535 vs 540 seconds; P 5 .62), estimated metabolic equivalent of tasks (METs; 11.6 vs 11.7; P 5 .80), maximum heart rate (174 vs 175 beats/min; P 5 .41), and heart rate at 2 minutes recovery (44 vs 43 beats/min; P 5 .28). In our secondary analysis, there was neither an association of SCT status with longitudinal changes in fitness nor an association with development of hypertension, diabetes, or metabolic syndrome after adjustment for sex, baseline age, body mass index, fitness, and physical activity. SCT is not associated with reduced fitness in this longitudinal study of young African American adults, suggesting the increased risk for exertion-related sudden death in SCT carriers is unlikely related to fitness. SCT status also is not an independent risk factor for developing hypertension, diabetes, or metabolic syndrome. (Blood. 2017;129(6):723-728) IntroductionSickle cell trait (SCT) is caused by the inheritance of a single copy of the variant b globin gene, which results in production of abnormal sickle hemoglobin. The coinheritance of 2 copies of the abnormal gene results in sickle cell anemia (SCA), a clinically significant blood disorder seen primarily among individuals of African or Afro-Caribbean descent. Historically, SCT, which is observed in 8% of the African American population in the United States, has been considered a clinically benign condition. Recent studies, however, suggest SCT may confer a higher risk for chronic kidney disease, thrombosis, stroke, and pregnancy-related complications in its carriers.1-6 Importantly, there is growing concern SCT may be associated with sudden death during strenuous physical activity and exercise, leading to the National College Athletics Association to mandate carrier status testing among all student athletes in division I institutions in 2010, and later in all division II and III institutions. [7][8][9] Growing evidence suggests SCT carriers may exh...

Granulocyte‐colony stimulating factor administration among hemoglobin S trait donors: A single center experience from the Eastern Mediterranean region

“…However, these individuals are susceptible to some environmental conditions including strenuous sports such as fitness, insufficient fluid intake, alcohol use, and low oxygen pressure . Individuals with Hemoglobin S trait are claimed to be under risk for thromboembolic events, rhabdomyolysis, cardiovascular system diseases, and sudden death …”

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Sickle cell trait knowledge and health literacy in caregivers who receive in‐person sickle cell trait education

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Characterization of a mouse model of sickle cell trait: parallels to human trait and a novel finding of cutaneous sensitization

“…While sickle cell trait (SCT) has been considered an essentially asymptomatic and benign condition associated with increased survival from malaria infection and normal life expectancy, recent studies have suggested that it may be associated with some complications of sickle cell disease (SCD) (Key et al , ) while other studies revealed no impact on baseline health and fitness (Liem et al , ). Individuals with SCT carry only a single copy of the mutated allele encoding the variant of haemoglobin that is known to cause SCD; the presence of normal β globin subunits within circulating red blood cells (RBCs) is protective against haemoglobin polymerization and RBC sickling.…”