SCREENING TOOLS FOR OBESITY

EVALUATION OF WAIST HIP RATIO, WAIST CIRCUMFERENCE AND BMI AMONG HYPERTENSIVE PATIENTS IN A TERTIARY CARE HOSPITAL

Abstract

Background: Various anthropometric tools employed to assess obesity include
body mass index (BMI) and waist to hip ratio (WHR) and waist circumference (WC) among
others. An increased prevalence of central obesity in Asians calls for evaluation of WHR, WC and
BMI as screening tools for obesity among them so as to give a clue about performance of these
screening 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, WHR
and WC as screening tools and analyzed and compared their performance in detecting obesity
among study subjects. Taking BMI as gold standard, the sensitivity and specificity of WHR and
WC was measured along with their positive and negative predictive values. Study subjects were
also categorized according to “BMI trigger points for public health consideration” risk categories
suggested 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 labelled
as obese by WC measurements compared to 209 by BMI (p-value 0.00 in both cases). This
showed a trend towards abdominal pattern of obesity among study subjects. The difference
was significant among male as well as female portions of study population, where out of 249
study subjects of male gender, 145 (58.23%) were categorized as obese according to WHR and
156 (62.65%) were labelled as obese according to WC, compared to 125 overweight or obese
by BMI (p-value 0.00). Females showed a similar trend with 98 (76.56%) out of 128 labelled
as obese by WC and 94 (73.43%) by WHR compared to 84 (65.62%) by BMI. The difference
between WHR and BMI in detecting obesity among females was a less significant compared
to males. Out of 377 total subjects, 335 fell into increased, high or very high risk categories
according to “BMI trigger points for public health consideration”. WC showed a sensitivity of
97.13% and specificity of 69.64% whereas WHR showed a sensitivity of 96.65% and specificity
of 77.98% when compared as screening tools with BMI as gold standard. Conclusions: WC
performed better as a screening tool for obesity when compared with WHR among hypertensive
patients. Higher number of obese patients detected by both WC and WHR than BMI showed
tendency towards central obesity among study subjects. This difference underscores the
relevance of using WC or WHR as measures of obesity especially among Pakistani population.