Adiposity has differing associations with incident coronary heart disease and mortality in the Scottish population: cross-sectional surveys with follow-up

OBJECTIVE: Investigation of the association of excess adiposity with three different outcomes: all-cause mortality, coronary heart disease (CHD) mortality and incident CHD. DESIGN: Cross-sectional surveys linked to hospital admissions and death records. SUBJECTS: 19 329 adults (aged 18-86 years) from a representative sample of the Scottish population. MEASUREMENTS: Gender-stratified Cox proportional hazards models were used to estimate hazard ratios (HRs) for all-cause mortality, CHD mortality and incident CHD. Separate models incorporating the anthropometric measurements body mass index (BMI), waist circumference (WC) or waist-hip ratio (WHR) were created adjusted for age, year of survey, smoking status and alcohol consumption. RESULTS: For both genders, BMI-defined obesity (>= 30 kg m(-2)) was not associated with either an increased risk of all-cause mortality or CHD mortality. However, there was an increased risk of incident CHD among the obese men (hazard ratio (HR) = 1.78; 95% confidence interval = 1.37-2.31) and obese women (HR = 1.93; 95% confidence interval = 1.44-2.59). There was a similar pattern for WC with regard to the three outcomes; for incident CHD, the HR = 1.70 (1.35-2.14) for men and 1.71 (1.28-2.29) for women in the highest WC category (men >= 102 cm, women >= 88 cm), synonymous with abdominal obesity. For men, the highest category of WHR (>= 1.0) was associated with an increased risk of all-cause mortality (1.29; 1.04-1.60) and incident CHD (1.55; 1.19-2.01). Among women with a high WHR (>= 0.85) there was an increased risk of all outcomes: all-cause mortality (1.56; 1.26-1.94), CHD mortality (2.49; 1.36-4.56) and incident CHD (1.76; 1.31-2.38). CONCLUSIONS: In this study excess adiposity was associated with an increased risk of incident CHD but not necessarily death. One possibility is that modern medical intervention has contributed to improved survival of first CHD events. The future health burden of increased obesity levels may manifest as an increase in the prevalence of individuals living with CHD and its consequences.