Objective: To determine the appropriate body mass index (BMI) and waist circumference (WC) cutoff point for identification
of at least one cardiovascular risk factor (hypertension, dyslipidemia, and type 2 diabetes) in Thailand, and to compare the
discrimination ability of BMI with that of WC for discrimination of at least one cardiovascular risk factor.
Material and Method: Baseline health survey data of participants of Thai Epidemiologic Stroke (TES) Study, who were
free from stroke, enrolled from five geographic regions around the country, were studied as cross-sectional analysis. Receiver
operating characteristics curve (ROC) analysis was performed to determine the appropriate cutoff points of BMI and WC
in identifying those with presence of at least one cardiovascular risk factors. The BMI or WC value with the shortest distance
on the ROC curve was considered to be appropriate cutoffs. Comparing the ability of BMI in discrimination of at least one
cardiovascular risk factor with that of WC was performed by comparing ROC area under curve (AUC).
Results: Among 19,621 (6,608 men and 13,013 women) participants with age range of 45 to 80 years, the average age was
59.8 years for men and 58.5 years for women. The appropriate cutoff point of BMI was 23 kg/m2
in men and 24 kg/m2
in
women. The cutoffs of WC were 80 cm and 78 cm in men and women, respectively. In both gender, waist circumference
(WC) (AUC in men = 0.684; 95% CI, 0.672-0.695, AUC in women = 0.673; 95% CI, 0.665-0.681) was significantly
(p < 0.001) better than BMI (AUC in men = 0.667; 95% CI, 0.656-0.679, AUC in women = 0.636; 95% CI, 0.628-0.644)
in discrimination of at least one cardiovascular risk factor.
Conclusion: In Thai adults aged 45 to 80 years, the cutoff points of BMI should be 23 kg/m2
in men and 24 kg/m2
in women.
For WC, 80 cm and 78 cm should be considered to be appropriate cutoffs for men and women, respectively. Waist circumference
(WC) as a simple obesity index should be advocated for public health screening.