Study Finds African-American Veterans Have Lower Mortality, CHD Than White Veterans
African-American veterans may have lower incidence of coronary heart disease (CHD) and lower all-cause mortality than white veterans, according to a study published Sept. 18 in Circulation. These results are in contrast with the higher mortality experienced by African-Americans in the general population.
The researchers, led by Csaba P. Kovesdy, MD, from the Memphis Veterans Affairs Medical Center, examined 547,441 African-American and 2,525,525 white patients with normal kidney function at baseline receiving care from the U.S. Veterans Health Administration and, in parallel analyses, compared outcomes in African-American versus white individuals in the National Health and Nutrition Examination Survey (NHANES) from 1999 to 2004. The mean age of the cohort at baseline was 59.9±14.0 years and 93.6 percent were men. The primary outcomes were all-cause mortality, incident CHD and incident ischemic strokes.
A total of 638,536 patients – 551,208 white and 87,328 African-American – died overall during a median follow-up of 7.9 years. The researchers found lower crude mortality rates in African-Americans for both men and women. These differences disappeared after adjusting for age in men, but remained slightly lower in African-American women. Compared to white patients who did not experience incident CHD or stroke, African-Americans without CHD or stroke had significantly lower mortality. However, after CHD or stroke, white and African-American patients had similar mortality. Adjusted all-cause mortality was higher in African-Americans overall. A total of 63,808 patients experienced an incident CHD event with 53,988 events in whites and 9,820 events in African Americans. Risk of CHD was lower in African-Americans. Finally, a total of 59,734 patients experienced an incident stroke with 46,984 events in whites and 12,750 events in African-Americans. Crude stroke rate was higher in African-Americans, but the risk lessened after adjustments, especially for socioeconomic characteristics. The analysis of NHANES showed higher all-cause mortality in African-Americans compared to whites in the general population.
The authors write that biological differences, overwhelmed by the socioeconomic disparities in the general population, may be a possible explanation for these racial discrepancies. They note that these genetic differences could affect other cardiovascular outcomes including a higher incidence of hypertension, more uncontrolled hypertension, and differences in central aortic blood pressure and prevalence of left ventricular hypertrophy in African-Americans.
In an accompanying editorial comment, Nakela L. Cook, MD, MPH, FACC, and George A. Mensah, MD, FACC, from the National Heart, Lung, and Blood Institute, write that these findings “[represent] a significant contribution to the literature as one of the few studies that demonstrates an attenuation of cardiovascular health disparities among African-Americans. The implications of these findings depend upon the generalizability and ability to extrapolate them more broadly within the [Veterans Health Affairs] system and beyond.”
“This study indicates a marked health-outcome advantage for African-American veterans with normal kidney function, over their non-African-American colleagues, and over African-Americans who are cared for outside of the Veterans Health Affairs system,” adds ACC President Kim Allan Williams, MD, FACC. “While this may point to the potential impact of kidney dysfunction (and likely many patients with hypertension and the renal-disease-predictive APOL1 phenotype common in African-Americans) on mortality, it also may be a clear reflection of a) access to physicians, b) availability of prescription drugs, c) a defined period of fitness in young adulthood that may extend health benefits later in life, and d) adaptability to regimentation necessary for the military, translating to medication adherence and other positive lifestyle variables.”
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