BMI, waist to height ratio and waist circumference as a screening tool for hypertension in hospital out patients: a cross-sectional study
Authors: Shrestha Rajan , Khatri Bijay , Upadhyay Madan P. , Bhattarai Janak R. , Kayastha Manish , Upadhyay Sanjib K 
Published: August 2020

Background: Obesity has become a global epidemic with a rise in noncommunicable diseases. It is now becoming the problem of low- and middle-income countries such as Nepal. Conventional risk factors are present in a high proportion in the Nepalese population. As a routine surveillance or registry system is absent, the actual burden and trend of obesity and hypertension in Nepal are unknown. Hypertension and other cardiovascular diseases can be prevented by detecting risk factors such as obesity and high blood pressure. A simple anthropometric measurement could be used to determine the risk of hypertension. However, the best predictor of hypertension remains contentious and controversial. We aimed to determine the burden of obesity and hypertension and test the ability to determine hypertension through different anthropometric measurements in hospital outpatients in a low-income setting.Methods: This hospital-based cross-sectional descriptive study was conducted from June to December 2019 among 40-69 year outpatients in a tertiary eye and ENT hospital in a semi-urban area of Nepal among a randomly selected sample of 2,256 participants from 6,769 outpatients visited in Health Promotion and risked factor screening service. We performed a correlation analysis to determine the relationship between anthropometric measurements and blood pressure. The area under the receiver operating characteristic (ROC) curve of body mass index (BMI), waist to height ratio (WHtR) and waist circumference (WC) was calculated and compared.Results: The mean (SD) age of the participants was 51.75 (8.47) years. The overall prevalence of obesity and overweight by BMI was 16.09% and 42.20%, respectively. The overall prevalence of abdominal obesity by waist-to-height ratio was 32.76%, which is higher than obesity by BMI. High waist circumference was observed among 66.76% participants, whereas female participants had a very higher prevalence of high waist circumference (77.46%) and male participants (53.73%) (p<0.001). The prevalence of hypertension among the participants with BMI≥25 kg/m2, WHtR≥0.5 and WC≥ cutoff values was 45.97%, 42.52% and 45.28%, respectively. The overall prevalence of hypertension and prehypertension was 40.67% and 36.77%, respectively. Male participants had a slightly higher prevalence of hypertension (42.72%) than female participants (39.00%). The areas under the curve (AUCs) were significantly higher than 0.5 for BMI (0.570, 95% CI: 0.548-0.592), WC (0.585, 95% CI: 0.563-0.607) and WHtR (0.586, 95% CI: 0.564-0.608). In both genders, the area under the curve was significantly higher than 0.5 (P<0.01). In all age groups, the area under the curve was also significantly higher than 0.5.Conclusion: Waist circumference was both correlated as well as had higher predictive capacity amongst WHtR and BMI and may play a major role in the future diagnosis of HTN in Nepali adults. Regardless of the anthropometric metrics used to measure overweight and obesity, the hospital setting is an opportunity centre to screen for overweight, obesity and hypertension, which are major risk factors for NCDs.