Objective Metabolic syndrome represents a unified condition of atherosclerotic diseases caused by abdominal obesity. The aims of this study were to examine the applicability of the prevalent fixed cut-off values of the abdominal circumference (AC) and body mass index (BMI) to age and gender groups and to identify suitable lifestyle modification factors. Methods We defined an outcome as having ≥ 2 risk components that are necessary to diagnose metabolic syndrome and examined the cross-sectional association of the AC and BMI with the outcome. We also assessed the effects of time-updated lifestyle information on metabolic traits using longitudinal data. Patients We enrolled 22,953 beneficiaries of a corporate health insurance scheme who underwent annual health examinations between January 2004 and December 2014. Results The AC [per 5-cm increase, odds ratio (OR) 1.17, 95% confidence interval (CI) 1.12-1.24] and BMI (OR 1.10, 95% CI 1.07-1.13) were significantly associated with the outcome, adjusted for age, gender, current smoking status, drinking habits, and other lifestyle information. The association between the outcome and AC was modified by gender (p for interaction = 0.033), and the association between the outcome and BMI was modified by age group (p for interaction = 0.049). In the longitudinal analysis, current smoking, drinking habits, and unhealthy eating habits were associated with an increased AC and BMI, whereas regular physical activity was associated with a decreased AC and BMI. Conclusion We showed that the association between the AC or BMI and metabolic syndrome was modified by gender or age group. Further studies will be needed to customize the national health screening and education programs.
Keywords: abdominal circumference; adiposity; metabolic syndrome; risk factors; universal health screening.