Misclassification of high-risk older subjects using waist action levels established for young and middle-aged adults - Results from the Rotterdam Study

OBJECTIVES: In the literature, cutoff points based on waist circumference (waist action levels) have been suggested to replace cutoff points based on body mass index (BMI) and waist-hip ratio (WHR) in identifying subjects who are overweight or obese and/or with central fat distribution. These cutoff points have been based on analysis in mainly middle-aged and younger adults. In this article, we examine the applicability of the suggested waist action levels in an older population. PARTICIPANTS: A total of 6423 men and women aged 55 or over participating in the Rotterdam Study, a population-based cohort study. MEASUREMENTS: Sensitivities and specificities of the proposed waist action levels in relation to the cutoff points for BMI and WHR were calculated. Also, cardiovascular risk factor levels at baseline examination in the different categories defined by high/low waist circumference, BMI and WHR were investigated. RESULTS: At waist action level 1 (waist circumference greater than or equal to 94 cm in men, greater than or equal to 80 cm in women), sensitivity was 71% in men and 86% in women for detecting those with high BMI (greater than or equal to 25 kg/m(2)) and/or WHR (greater than or equal to0.95 in men, greater than or equal to0.80 in women). At waist action level 2 (waist circumference greater than or equal to 102 cm in men, greater than or equal to 88 cm in women in comparison with BMI greater than or equal to 30 kg/m(2) and/or WHR greater than or equal to0.95 in men, greater than or equal to0.80 in women), sensitivity was considerably lower: 35% in men and 59% ill women. This was mainly due to a large proportion of subjects with low waist and BMI but high WHR. Specificity was high (>90%) at both action levels. Cardiovascular disease risk factors, except smoking, tended to increase with increasing waist circumference, WHR, and BMI. CONCLUSIONS: The suggested cutoff points for waist circumference are only to a limited degree useful in identifying subjects with overweight and obesity and/or central fat distribution in an older population. This concerns especially the upper cutoff point (waist action level 2) and is mainly due to the increased central distribution of fat with advancing age.