Screening Tools for Obesity

Abstract

Background: Various anthropometric tools employed to assess obesity includebody mass index (BMI) and waist to hip ratio (WHR) and waist circumference (WC) amongothers. An increased prevalence of central obesity in Asians calls for evaluation of WHR, WC andBMI as screening tools for obesity among them so as to give a clue about performance of thesescreening measures in detection of obesity. Study Design: Cross sectional analytical study.Setting: Allied Teaching Hospital Faisalabad. Study Period: December, 2014 to November,2015. Methods: 377 patients of essential hypertension screened for obesity, using BMI, WHRand WC as screening tools and analyzed and compared their performance in detecting obesityamong study subjects. Taking BMI as gold standard, the sensitivity and specificity of WHR andWC was measured along with their positive and negative predictive values. Study subjects werealso categorized according to “BMI trigger points for public health consideration” risk categoriessuggested by WHO for Asian populations. Results: Among 377 study subjects, 239 (63.39%)were categorized as obese by WHR measurements and 254 (67.33%) individuals were labelledas obese by WC measurements compared to 209 by BMI (p-value 0.00 in both cases). Thisshowed a trend towards abdominal pattern of obesity among study subjects. The differencewas significant among male as well as female portions of study population, where out of 249study subjects of male gender, 145 (58.23%) were categorized as obese according to WHR and156 (62.65%) were labelled as obese according to WC, compared to 125 overweight or obeseby BMI (p-value 0.00). Females showed a similar trend with 98 (76.56%) out of 128 labelledas obese by WC and 94 (73.43%) by WHR compared to 84 (65.62%) by BMI. The differencebetween WHR and BMI in detecting obesity among females was a less significant comparedto males. Out of 377 total subjects, 335 fell into increased, high or very high risk categoriesaccording to “BMI trigger points for public health consideration”. WC showed a sensitivity of97.13% and specificity of 69.64% whereas WHR showed a sensitivity of 96.65% and specificityof 77.98% when compared as screening tools with BMI as gold standard. Conclusions: WCperformed better as a screening tool for obesity when compared with WHR among hypertensivepatients. Higher number of obese patients detected by both WC and WHR than BMI showedtendency towards central obesity among study subjects. This difference underscores therelevance of using WC or WHR as measures of obesity especially among Pakistani population.