Comparison of waist-to-hip ratio and other obesity indices as predictors of cardiovascular disease risk in people with type-2 diabetes: a prospective cohort study from ADVANCE

Abstract

Aims: The aim of this study was to compare the strength of associations and discrimination capability of body mass index (BMI), waist circumference (WC) and waist-to-hip ratio (WHR) with cardiovascular disease risk in individuals with type-2 diabetes.

Methods and results: Eleven thousand, one hundred and forty men and women were followed for a mean of 4.8 years. The Cox proportional hazard models were used to compute the hazard ratios and 95% confidence intervals (95% CI) for one standard deviation (SD) increase in baseline BMI (SD: 5 kg/m2), WC (SD: 13 cm) and WHR (SD: 0.08) with cardiovascular disease risk. After adjustment, hazard ratio (95% CI) for WC were 1.10 (1.03–1.18) for cardiovascular events, 1.13 (1.03–1.24) for coronary events, and 1.08 (0.98–1.19) for cardiovascular deaths. Estimates for WHR were 1.12 (1.05–1.19), 1.17 (1.08–1.28) and 1.19 (1.09–1.31). BMI was not related to any of these outcomes. Although the receiver operating characteristic curve could not differentiate between anthropometric variables (P values 0.24), the relative integrated discrimination improvement statistic showed an enhancement in the discrimination capabilities of models using WHR for cardiovascular outcomes, except for cerebrovascular events.

Conclusion: Strengths of associations and discrimination statistics suggested that WHR was the best predictor of cardiovascular events and mortality in patients with type-2 diabetes and BMI the worst.

Figure 1

Adjusted hazard ratios and 95% confidence intervals (95% CI) for major cardiovascular outcomes per standard deviation increment in anthropometric variables All analyses were adjusted by age, gender, smoking status, treatment allocation and ethnicity. Boxes are for the point estimates (hazard ratios) and the horizontal bars represent the 95% confidence intervals. The size of the box is proportional to the inverse variance of the natural logarithm of the hazard ratio. Delta likelihood Ratio χ2 = difference in the likelihood ratio χ² statistics for each event category calculated by comparing multivariate regression models without and with a single anthropometric variable to assess improvement in model fit. BMI = body mass index, WC = waist circumference, WHR = waist-to-hip ratio. Standard deviations are 5 kg/m² for BMI, 13 cm for WC and 0.08 for WHR.

Figure 2

Adjusted hazard ratios and 95% confidence interval (95% CI) for major cardiovascular outcomes comparing the fifths for each anthropometric variable. All analyses were adjusted by age, gender, smoking status, treatment allocation and ethnicity. Boxes are for the point estimates (hazard ratios) and the horizontal bars represent the 95% confidence intervals. The size of the box is proportional to the inverse variance of the natural logarithm of the hazard ratio. BMI = body mass index, WC = waist circumference, WHR = waist-to-hip ratio.