BMI, waist to height ratio and waist circumference as a screening tool for hypertension in hospital outpatients: a cross-sectional, non-inferiority study

Objective This non-inferiority study aimed to determine the burden of obesity in a hospital outpatient setting of a developing country, using three commonly employed metrics as predictors of hypertension (HTN). Design A cross-sectional study design was adopted. Setting This study was conducted in Health Promotion and Risk Factor Screening Services of a tertiary hospital for eye and ear, nose, throat in a semiurban area of Nepal. Participants 2256 randomly selected outpatients between 40 and 69 years old. Outcome measures The three obesity metrics and HTN were analysed for association using correlation, the area under the receiver operating characteristic (ROC) curve and ORs. Results The prevalence of obesity or overweight by body mass index (BMI) was 58.29%; by waist-to-height ratio (WHtR) was 85.95%, high waist circumference (WC) was observed among 66.76% of participants. Female participants had a greater prevalence of high WC (77.46%) than males (53.73%) (p<0.001). Prevalence of HTN and pre-HTN were 40.67% and 36.77%, respectively. The areas under the ROC curve were significantly higher than 0.5 for BMI (0.593), WHtR (0.602) and WC (0.610). Conclusion This study showed that WHtR and WC measured were not inferior to BMI as a metric for obesity detection and HTN prediction. Because of its low cost, simplicity of measurement and better ability to predict HTN, it may become a more usable metric in health facilities of low-income and middle-income countries.