Attributable mortality burden of metabolic syndrome: comparison with its individual components.

Aim: To estimate the national prevalence, mortality risk and population mortality burden of metabolic syndrome, and compare the values with those of its individual components.

Methods and results: A total of 486,341 apparently healthy adults who went through a screening programme in Taiwan were recruited from 1994 onwards. As of 2007, 15,268 deaths had occurred at least one year after the examination. Six definitions of metabolic syndrome were used. Components of metabolic syndrome include obesity, hypertension, hyperglycaemia, dyslipidaemia and albuminuria. Hazard ratios (HRs) were calculated using the Cox proportional hazard model. The population mortality burden considered both national prevalence and HRs. The national prevalence of metabolic syndrome defined by the Adult Treatment Panel (ATP) III was 16.3%, the HR for all causes was 1.36 (95%, CI 1.31-1.41) and the HR for cardiovascular disease (CVD) was 1.63 (95%, CI 1.51-1.77). The population mortality burden of metabolic syndrome was 5.5% for all causes, in contrast to 9.0% for hypertension, 8.9% for albuminuria, 6.6% for diabetes, 3.5% for dyslipidaemia and 1.5% for obesity. For CVD it was 9.4%, lower than 10.7% for albuminuria and 25.0% for hypertension.

Conclusion: The mortality burden of metabolic syndrome was relatively small at national level. Three of the five components of metabolic syndrome alone, namely hypertension, diabetes and albuminuria, contributed more than metabolic syndrome to all-cause mortality. Successful management of any of these three components would have achieved a greater impact on mortality than management of metabolic syndrome.