Evaluating CMR

Health-Related Waist Circumference Cut-offs

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Abdominal obesity is commonly assessed using waist circumference, and common measurement protocols include the visible narrowing of the waist, last rib, top of the iliac crest, or the midpoint between the last rib and the iliac crest. Current Canadian clinical practice guidelines and the National Institutes of Health (NIH) in the United States recommend measuring waist circumference using the iliac crest as the landmark (10, 11). Accordingly, the International Chair on Cardiometabolic Risk also recommends measuring waist circumference at the top of the iliac crest. The NIH has published sex-specific waist circumference thresholds (men: 102 cm, women: 88 cm) to denote increased health risk within each BMI category (11). However, unlike BMI categories, these waist circumference cut-offs were not based on their association with morbidity or mortality, but were instead based on waist circumference values corresponding to a BMI of 30 kg/m2 in Caucasian men and women. These waist circumference thresholds seem appropriate for non-Hispanic blacks and Mexican Americans (12), but are likely too high for most Asian populations (13) and are unknown for other ethnic groups. The appropriate cut-offs for determining health risk in Asian and other ethnic populations are still being studied, but reported values for Asians range from 85 to 90 cm for men and 80 to 90 cm for women (13). For instance, the International Diabetes Federation position statement on the metabolic syndrome and its clinical diagnosis has lowered waist girth values to 94 cm for European men, while recognizing the need to propose cut-offs specific to various ethnic populations.

Within a given BMI category, individuals with a waist circumference greater than the proposed thresholds generally have a worse metabolic profile than individuals with a waist circumference below these thresholds (6). Moreover, high waist circumference predicts a later decline in insulin sensitivity over a 5 year follow-up (7). It has also been reported that once waist circumference is taken into account, BMI does not provide any added information in terms of predicting metabolic risk (8). For these reasons, it is important to measure waist circumference when assessing health risk. 

Reference

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6. Janssen I, Katzmarzyk PT and Ross R. Body mass index, waist circumference, and health risk: evidence in support of current National Institutes of Health guidelines. Arch Intern Med 2002; 162: 2074-9.

7. Karter AJ, D'Agostino RB, Jr., Mayer-Davis EJ, et al. Abdominal obesity predicts declining insulin sensitivity in non-obese normoglycaemics: the Insulin Resistance Atherosclerosis Study (IRAS). Diabetes Obes Metab 2005; 7: 230-8.

8. Janssen I, Katzmarzyk PT and Ross R. Waist circumference and not body mass index explains obesity-related health risk. Am J Clin Nutr 2004; 79: 379-84.

10. Lau DC, Douketis JD, Morrison KM, et al. 2006 Canadian clinical practice guidelines on the management and prevention of obesity in adults and children. CMAJ 2007; 176: S1-117.

11. Clinical Guidelines on the Identification, Evaluation, and Treatment of Overweight and Obesity in Adults--The Evidence Report. National Institutes of Health. Obes Res 1998; 6 Suppl 2: 51S-209S.

12. Zhu S, Heymsfield SB, Toyoshima H, et al. Race-ethnicity-specific waist circumference cutoffs for identifying cardiovascular disease risk factors. Am J Clin Nutr 2005; 81: 409-15.

13. Alberti KG, Zimmet P and Shaw J. The metabolic syndrome--a new worldwide definition. Lancet 2005; 366: 1059-62.

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