Hypertension and obesity in adults living in a high HIV prevalence rural area in South Africa

Abstract

Hypertension and excess body weight are major risk factors of cardiovascular morbidity and mortality in developing countries. In countries with a high HIV prevalence, it is unknown how increased antiretroviral treatment and care (ART) coverage has affected the prevalence of overweight, obesity, and hypertension. We conducted a health survey in 2010 based on the WHO STEPwise approach in 14,198 adult resident participants of a demographic surveillance area in rural South Africa to investigate factors associated with hypertension and excess weight including HIV infection and ART status. Women had a significantly higher median body mass index (BMI) than men (26.4 vs. 21.2 kg/m(2), p<0.001). The prevalence of obesity (BMI ≥ 30 kg/m(2)) in women (31.3%, 95% confidence interval (CI) 30.2-32.4) was 6.5 times higher than in men (4.9%, 95% CI 4.1-5.7), whereas prevalence of hypertension (systolic or diastolic blood pressure ≥ 140 or 90 mm Hg, respectively) was 1.4 times higher in women than in men (28.5% vs 20.8%, p<0.001). In multivariable regression analysis, both hypertension and obesity were significantly associated with sex, age, HIV and ART status. The BMI of women and men on ART was on average 3.8 (95% CI 3.2-3.8) and 1.7 (95% CI 0.9-2.5) kg/m(2) lower than of HIV-negative women and men, respectively. The BMI of HIV-infected women and men not on ART was on average 1.2 (95% CI 0.8-1.6) and 0.4 (95% CI -0.1-0.9) kg/m(2) lower than of HIV-negative women and men, respectively. Obesity was a bigger risk factor for hypertension in men (adjusted odds ratio (aOR) 2.99, 95% CI 2.00-4.48) than in women (aOR 1.64, 95% CI 1.39-1.92) and overweight (25 ≤ BMI<30) was a significant risk factor for men only (aOR 1.53 95% CI 1.14-2.06). Our study suggests that, cardiovascular risk factors of hypertension and obesity differ substantially between women and men in rural South Africa.

Figure 1. Flow diagram of individuals participating in the various aspects of the health and demographic surveillance.

Non-contacts refer to eligible individuals who were not contacted due to death, illness or had out-migrated outside the demographic study area.

Figure 2. Distribution of body mass index by age group in (A) women and (B) men.

BMI categories (underweight: less than 18.5 kg/m²; normal: between 18.5 and 25 kg/m²; overweight: between 25 and 30 kg/m²; obese: greater than 30 kg/m²) .

Figure 3. Distribution of hypertension by age group in (A) women and (B) men.

Hypertension categories (normal: systolic BP less 120 or diastolic BP less 80 mmHg; stage-I hypertension: systolic BP between 140–160 mmHg and/or diastolic BP between 90–100 mmHg; stage-II hypertension: systolic BP greater 160 mmHg and/or diastolic BP greater than 100 mmHg).