Agreement between specific measures of adiposity and associations with high blood pressure in black South African women

Abstract

Objectives To derive percentage body fat (%BF) cut-points according to body mass index (BMI) categories for adult black South African women and to investigate the agreement between adiposity classifications according to WHO BMI and %BF cut-points. The secondary aim was to determine the association between these different adiposity measures and high blood pressure. Methods Black women aged 29–65 years (n = 435) from Ikageng, South Africa, were included in this cross-sectional study. Socio-demographic and anthropometric data were collected (weight, height and BMI). %BF using dual-energy X-ray absorptiometry and blood pressure were measured. Results There was significant agreement between three %BF categories: low/normal (<35.8% age 29–49 years; or <38% age 50–65 years), overweight range (35.8–40.7% age 29–49 years; or 38–42.1% age 50–65 years) and obese (≥40.7% age 29–49 years; or ≥42.1% age 50–65 years) and three BMI categories: low/normal (<25 kg/m2), overweight range (25–29.9 kg/m2) and obese (≥30kg/m2); (κ = 0.62, P < .0001). Despite statistically significant agreement between groups, more than half of overweight individuals were misclassified as having either a normal (30.2%) or obese %BF (25.5%). %BF misclassification was low in the low/normal and obese BMI ranges. After adjustment for confounders, obesity (BMI ≥ 30kg/m2), as well as high %BF were significantly associated with high blood pressure (OR = 1.75, 95% CI 1.09–2.81 versus OR = 1.92, 95% CI 1.15–3.23, respectively). Conclusion Despite significant agreement between BMI and %BF categories, considerable misclassification occurred in the overweight range. Participants with excessive %BF had a greater odds of high blood pressure than those in the highest BMI category