Obesity among African-American stroke survivors increases risk factors for recurrent stroke

Obesity may put African-Americans who have survived one stroke at risk for a second stroke by increasing their risk of hypertension (high blood pressure), diabetes and high cholesterol, according to an article in the March issue of Archives of Neurology, one of the JAMA/Archives journals.

Obesity has become epidemic in the United States and African-Americans have the highest rate of obesity, nearly 40 percent, as reported in the 1999-2000 National Health and Nutritional Examination Survey (NHANES), according to background information in the article. Obesity is associated with a number of negative health consequences, including insulin resistance, hypertension, dyslipidemia (high cholesterol levels or other lipid level problems), stroke, coronary artery disease and decreased life expectancy.

Sean Ruland, D.O., of the University of Illinois at Chicago, and colleagues analyzed data from African-American patients enrolled in a study of treatment for prevention of stroke recurrence (the African-American Antiplatelet Stroke Prevention Study [AAASPS]) to determine the association between obesity and cardiovascular risk factor profiles for African-American stroke survivors. Using baseline data on height and weight, the researchers determined the body mass index (BMI, calculated as weight in kilograms divided by the square of height in meters) for 1,711 patients. The patients were divided into six groups, underweight (BMI less than 18.5), normal weight (BMI 18.5 - 24.9), overweight ((BMI 25.0 - 29.9), class one obesity (BMI 30.0 - 34.9), class two obesity (BMI 35.0 - 39.9) and class three obesity (BMI greater than 40.0).

The researchers compared patients' BMI with the cardiovascular risk factors, hypertension (HTN), diabetes mellitus (DM) and dyslipidemia (DL). Overall, 76 percent of the patients (70 percent of men and 81 percent of women) were overweight or obese. Nearly 20 percent of women younger than 55 years and 7.0 percent of men in that age group qualified as class three obese.

Presence of diabetes mellitis increased with increasing BMI for both men and women. Although the proportion of patients with hypertension was high for all weight categories, blood pressure also increased with increased BMI, although more modestly. The proportion with dyslipidemia increased with increasing BMI for men, but not for women. In this study, the authors defined metabolic syndrome as the presence of obesity, hypertension, diabetes and dyslipidemia, and found that the three risk factors (hypertension, dyslipidemia and diabetes) were present in 26.1 percent of men and 34.7 percent of women with class one obesity, in 29.4 percent of men and 31.3 percent of women with class two obesity and in 43.3 percent of men and 29.1 percent of women with class three obesity. Metabolic syndrome increases cardiovascular risk more than any of the individual factors which comprise it.

"A metabolic syndrome was seen in 21 percent of men and 29 percent of women in the AAASPS," the authors write. 'Although BMI was not an independent predictor of stroke occurrence, obesity nearly doubled the odds of having a metabolic syndrome compared with the odds of those with a normal BMI having DM, HTN and DL. Furthermore, increasing BMI had a negative association with blood pressure and glycemic [blood sugar] control."

"Our data support the association of increasing risk factor profiles and decreasing risk factor control with increasing weight," the authors conclude. "This is particularly important in African American stroke survivors, as this group has been shown to have a worse risk factor profile than their non-African-American counterparts, putting them at high risk for recurrent stroke. Furthermore, the high morbidity [illness] and mortality [death] due to stroke in African-Americans should make this an increasing area of public health concern."