Sickle cell trait not tied to higher risk for MI, CHD in Black individuals
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Sickle cell trait was not associated with increased risk for MI or CHD in Black individuals, according to a cohort study published in JAMA Network Open.
“The associations of hypertension with CHD and of the apolipoprotein L1 (APOL1) risk gene variant ... have raised the question of a possible association between genetic variation and some of the observed excess and unexplained burden of CHD among African American individuals,” Hyacinth I. Hyacinth, MD, PhD, MPH, of the Aflac Cancer and Blood Disorder Center of Children's Healthcare of Atlanta, assistant professor at Emory University School of Medicine, and colleagues wrote. “Although there have been inconsistent findings for the association between APOL1 genotypes and CVD, there is a rationale that genetic variation is possibly associated with the observed disparities in the incidence and prevalence ... among African American individuals.”
In a cohort study, researchers analyzed 23,197 Black participants (70% women; mean age, 50-64 years; sickle cell trait [SCT] prevalence, 7.7%) from five prospective, population-based cohorts for associations between SCT and the incidence of MI or composite CHD outcomes. Researchers estimated incidence HRs and further compared incidence between SCT carriers and non-SCT carriers.
The researchers found 1,034 participants (76 with SCT) had incidence of MI and 1,714 participants (137 with SCT) had incidence of composite CHD outcome.
MI incidence rates were 3.8 (95% CI, 3.3-4.5) per 1,000 person-years in participants with SCT and 3.6 (95% CI, 2.1-5.1) per 1,000 person-years in participants without SCT. Incidence rates of CHD events were 7.3 (95% CI, 5.5-9.7) per 1,000 person-years in those with SCT and 6 (95% CI, 4.9-7.4) per 1,000 person-years in those without it.
There was no significant association between SCT status with either MI outcomes (HR = 1.05; 95% CI, 0.81-1.32) or CHD outcomes (HR = 1.16; 96% CI, 0.92-1.47), the researchers wrote.
“Although prior studies showed that SCT is associated with sudden death, our findings suggest that these disorders may not be associated with SCT-related sudden death,” Hyacinth and colleagues wrote.
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Kim Allan Williams Sr., MD, MACC, FAHA, MASNC, FESC
These are not particularly surprising findings, but I am surprised by the conclusions: The authors did not rule out an association. An HR of 1.16 for CHD is very large — one extra event in every six people. Not reaching statistical significance suggests that the event number/population size was too small, rendering a possible type II statistical error, accepting the null hypothesis when it is actually false. My suggestion would be a larger study to confirm or refute that one of six people with SCT will have an added event.
The CV management strategy for patients with SCT should be to use the 2019 American College of Cardiology/American Heart Association Guideline on the Primary Prevention of Cardiovascular Disease — lifestyle with predominantly or exclusively plant-based nutrition; limiting cholesterol, saturated fat, refined grains and sweet beverages; and daily exercise. Further, use high-dose statins for ACS (as ACC guidelines recommend) and pull out all stops on prevention strategies for patients with SCT.
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