Relative importance of body mass index and waist circumference for hypertension in adults

OBJECTIVE: To assess the relative importance of Body Mass Index (BMI) and waist circumference for the determination of hypertension in adults. METHODS: Cross sectional analysis of a sample of employees (N=1,584), aged 18 to 64 years, from a private general hospital in the city of Sao Paulo, Brazil. Data collection included the application of a structured questionnaire and blood pressure, weight, high, and waist circumference measurements. Hypertension was defined as blood pressure levels >= 140/90 mmHg or reported use of anti-hypertensive medication. The relative importance of BMI and waist circumference was evaluated by calculating the attributable fraction of hypertension corresponding to each anthropometric indicator, employing both the usual cut-off points as well as cut-off points based on the observed distribution of the indicator in the population. In addition, an indicator combining simultaneously BMI and abdominal circumference values was also developed. RESULTS: Prevalence of hypertension was 18.9% (26.9% in men and 12.5% in women). In men, the fraction of hypertension attributable to BMI exceeded the fraction attributable to waist circumference based on the usual cut-off points for the indicators (56% vs. 48%, respectively) and also considering the quartiles of the observed distribution for these indicators (73% vs. 69%, respectively). In women, the fraction of hypertension attributable to waist circumference was slightly higher than the fraction attributable to BMI based on the usual cut off points for both indicators (44% vs. 41%), but the reverse was true when quartiles of the observed distribution were used (41% vs. 57%, respectively). In women only, the fraction of hypertension attributable to the indicator combining BMI and waist circumference (64%) was higher that observed using each indicator alone. CONCLUSIONS: Both BMI and abdominal circumference were positively and independently associated with the occurrence of arterial hypertension, the influence of BMI being higher among men.