Background: It is unclear which anthropometric obesity indicator best predicts adverse health outcomes. This study aimed to investigate the association of body mass index (BMI), waist circumference (WC), waist-to-height ratio (WHtR), waist-to-hip ratio (WHR), and hip-adjusted WC with all-cause and cardiovascular mortality.
Methods: 50045 people aged 40–75 (58% women, median BMI: 26.3 kg /m2 ) participated in the population-based Golestan Cohort Study. We used Cox regression to estimate hazard ratios (HRs) and 95% confidence intervals (95% CI) for the association of obesity indicators with mortality. We also examined the association of these indicators with intermediate outcomes, including hypertension, blood glucose, dyslipidemia, carotid atherosclerosis, nonalcoholic fatty liver, and visceral abdominal fat.
Results: After a median follow-up of 10.9 years (success rate: 99.1%), 6651 deaths (2778 cardiovascular) occurred. Comparing 5th to the 1st quintile, HRs (95% CIs) for all-cause and cardiovascular mortality were 1.12 (1.02–1.22) and 1.59 (1.39–1.83) for BMI, 1.16 (1.07–1.27) and 1.66 (1.44–1.90) for WC, 1.28 (1.17–1.40) and 1.88 (1.63–2.18) for WHtR, 1.44 (1.32–1.58) and 2.04 (1.76–2.36) for WHR, and 1.84 (1.62–2.09) and 2.72 (2.23–3.32) for hip-adjusted WC, respectively. Hip-adjusted WC had the strongest associations with the intermediate outcomes.
Conclusion: Indicators of visceral adiposity (e.g., hip-adjusted WC) were much stronger predictors of overall and cardiovascular mortality than were indicators of general adiposity (e.g., BMI). The full-strength effect of visceral adiposity becomes apparent only when both WC, as a risk factor, and hip circumference, as a protective factor, are individually and simultaneously taken into consideration.