Is Waist to Height Ratio a Better and More Practical Measure of Obesity to Assess Cardiovascular or Diabetes risk in Indians?

Sir,

In response to the editorial by V Mohan and M Deepa.1 I would like to point another measure of obesity appropriate to Indians.  It has been rightly pointed that Indians have higher abdominal adiposity, measured as the waist-to-hip ratio or waist circumference, although they have lean body mass. However measuring hip circumference in community settings (or even in clinic situation) is difficult due to cultural reasons. Further when measured in fully clothed subjects, it will be inaccurate. We, therefore, explored if height was a good surrogate for hip measurement in a cross-sectional survey led by KS Reddy, which was carried out among a stratified random sample of industrial employees and their family members (10930 individuals, mean age 39.6 years, men: 6764) employed in eleven medium to-large industries located at eleven diverse sites in India.2 Waist circumference to height ratio (WC-HR) was calculated by dividing waist circumference (expressed in centimeters) with height (expressed in centimeters). We found that waist to height ratio (WC-HR) had a higher predictive power for diabetes than waist circumference and BMI and there was a better continuous relationship for WC-HR as compared to waist circumference or BMI. Similar superior predictive value was demonstrated with ROC curves for WC-HR, with a higher area under the curve showing a better predictive value for diabetes associated with it. Hence we believe that risk scores based on WC-HR for predicting diabetes or cardiovascular risk could be an alternate and more practical method compared to other measures of obesity in Indians. Parikh et al3 reported a novel index of central obesity that was based on measurement of waist size and body height to predict cardiovascular risk. Recent reports from Asian populations in Iran4 and Bangladesh5 have demonstrated that among obesity measurements, WC-HR has the best predictive value for diabetes as compared to BMI and WC. Similar to our study the Iranian study employed ROC curve analysis which showed a higher area under ROC curve for WC-HR.

PP Joshi

Associate Professor, Department of Medicine, Indira Gandhi Government Medical College, Nagpur 440033

References

1.     Mohan V, Deepa M. Measuring obesity to assess cardiovascular risk – inch tape, weighing machine, or both.  J Assoc Physicians India 2007;55:617.

2.     Ajay VS, Prabhakaran D, Jeemon P, Thankappan KR, Mohan V, Ramakrishnan L, Joshi P, Ahmed FU, Mohan BVM, Chaturvedi V, Mukherjee R, Reddy KS. Prevalence and determinants of diabetes mellitus in the Indian Industrial population Under consideration for publication.

3.     Parikh RM, Joshi SR, Menon PS, Shah NS. Index of central obesity: a novel parameter. Med Hypotheses 2007;68:1272-5.

4.     Hadaegh F, Zabetian A, Harati H, Azizi F. Waist/height ratio as a better predictor of type 2 diabetes compared to body mass index in Tehranian adult men - a 3.6-year prospective study. Exp Clin Endocrinol Diabetes 2006;114:310-15.

5.     Sayeed MA, Mahtab H, Latif ZA, et al. Waist-to-height ratio is a better obesity index than body mass index and waist-to-hip ratio for predicting diabetes, hypertension and lipidemia. Bangladesh Med Res Counc Bull 2003;29:1-10.

 

Reply to the Author

Sir,

There are multiple measures of obesity.1 These range from time tested measures such as weight and body mass index  to more complex clinical measures that determine regional distribution of fat such as subscapular skin-fold thickness, multi-site skin fold thickness, arm or thigh thickness, and abdominal girth. After the recognition that intra-abdominal fat was metabolically active and a major predictor of cardiovascular risk, multiple measures for its determination have evolved. These include measurement of waist circumference, waist length, sagittal waist diameter, waist-hip ratio, waist-height ratio, waist circumference-waist length ratio, and others.2 Some of these measures have been tested in prospective epidemiological studies and waist circumference has been reported to be the most significant positive predictor of cardiovascular risk factors and cardiovascular events.3 The gold standard of measurement of adiposity remains measurement of double-labeled water using radioactive techniques and dual-energy X-ray absorptiometry (DEXA) scan.2 Regional distribution can be measured using either the DEXA, computed tomography or magnetic resonance imaging scans.2 Each of these techniques have their pros and cons and the clinical use for determining cardiovascular risk depends on their positive or negative predictive value.3

Our article reported that obesity measured by either a high body mass index, waist size or waist-hip ratio are equal in predicting cardiovascular risk.4 In the accompanying editorial Mohan et al5 have opined that measurement of waist-size is a simple and reliable estimate of cardiovascular risk although multiple arguments could be placed in favor or against this simple yet technically demanding measure. The INTERHEART study6 reported that elevated waist-hip ratio was an important predictor of acute myocardial infarction and high waist-size as well as low hip-size were significant predictors of risk. Parikh et al7 reported a novel index of central obesity that was based on measurement of waist size and body height to predict cardiovascular risk. Joshi8 suggests that waist-height ratio is a useful measure of intra-abdominal adiposity. To establish this hypothesis data from the national non-communicable disease risk factor surveillance are presented that clearly show that high waist-height ratio predicts cardiovascular risk. Multiple studies from other countries have evaluated importance of waist-height ratio and a British Study succinctly concludes that waist circumference should be less than half of height for preventing cardiovascular risk.9

We determined the role of waist-height ratio in prediction of cardiovascular risk in the same cohort reported in the JAPI article4 (Table 1). Mean waist-height ratio in men was 0.54 ± 0.09 and in women was 0.55 ± 0.09. Quartiles of waist-hip ratios were generated and prevalence of cardiovascular risk factors determined in each group. In both men and women in the study cohort there is a significantly escalating trends in prevalence of cardiovascular risk factors- hypertension, lipid abnormalities, diabetes and the metabolic syndrome- with increasing waist-height ratio. These trends are essentially similar to those reported with body mass index, waist size or waist hip ratio.4 We conclude that the waist-height ratio is similar in predictive capacity to the measures reported in the article.4 However, these and some other studies from India10 that report on adiposity-cardiovascular risk associations are essentially cross-sectional studies and the definitive pathophysiological role of an individual measure of obesity or intra-abdominal obesity can be determined only by long-term prospective studies. The jury is still open.

R Gupta*, VP Gupta**

*Department of Medicine, Fortis Escorts Hospital, Malviya Nagar, Jaipur 302017.**Department of Statistics, University of Rajasthan, Jaipur 302004.

References

1.     WHO Expert Committee. Physical status: the use and interpretation of anthropometry. Geneva. World Health Organization 1995;4-36.

2.     Han TS, Sattar N, Lean M. Assessment of obesity and its clinical implications. BMJ 2006;333:695-98.

3.     Haslam D, Sattar N, Lean M. Obesity: time to wake up. BMJ 2006;333:640-2.

4.     Gupta R, Rastogi P, Sarna M, et al. Body-mass index, waist-size, waist-hip ratio and cardiovascular risk factors in urban subjects. J Assoc Physicians India 2007;55:621-7.

5.     Mohan V, Deepa M. Measuring obesity to assess cardiovascular risk: inch tape, weighing machine or both? J Assoc Physicians India 2007;55:617-9.

6.     Yusuf S, Hawken S, Ounpuu S, et al. Obesity and the risk of myocardial infarction in 27000 participants from 52 countries: a case-control study. Lancet 2005;366:1640-9.

7.     Parikh RM, Joshi SR, Menon PS, Shah NS. Index of central obesity: a novel parameter. Med Hypotheses 2007;68:1272-5.

8.     Joshi PP. Is waist to height a better and more practical measure of obesity to assess cardiovascular or diabetes risk in Indians? J Assoc Physicians India 2007; 55: In press.

9.     McCarthy HD, Ashwell M. A study of central fatness using waist-to-height ratios in UK children and adolescents over two decades supports the simple message: “keep your waist circumference to less than half your height”. Int J Obesity 2006;30:988-92.

10.          Misra A, Vikram NK, Gupta R, et al. Waist circumference cut-off points and action levels for Asian Indians for identification of abdominal obesity. Int J Obesity 2006;30:
106-11.