a1 University Department of Human Nutrition, Royal Infirmary Queen Elizabeth Building, Alexandra Parade, Glasgow G31 2ER, UK
a2 Wolfson College, University of Cambridge, Cambridge CB3 9BB, UK
We evaluated the accuracy of self-reported home-assessed and self-measured waist circumference in 101 men and eighty-three women aged 28–67 years. The main outcome measures were subjects' self-reported and self-measured waist circumference, and self-classification according to the previously defined waist action level 1 (940 mm in men, 800 mm in women) and action level 2 (1020 mm in men, 880 mm in women), and waist circumference measured by the investigator using the ‘Waist Watcher’ tape-measure, as the reference method. The mean errors (95% CI limits of agreement) for subjects' self-reported waist circumference (self-reported minus reference; mm) were −67 (95% CI −210, 77) in men and −43 (95% CI −211, 123) in women, and for self-measured waist circumference (mm) using the ‘Waist Watcher’ (self-measured minus reference) were −5 (95% CI −62, 52) in men and −4 (95% CI −50, 42) in women. The proportions of subjects classified into waist action level 1 or action level 2 by the investigator were used as the reference method. Self-reported waist circumference of men and women respectively would be classified correctly in different categories based on action level 1 with sensitivities of 58·3 and 78·7%, and specificities of 98·5 and 98·7%, and action level 2 with sensitivities of 38·3 and 48·9%, and specificities of 98·5 and 98·7%. Using the ‘Waist Watcher’ with different colour bands based on the action levels, male and female subjects respectively classified themselves into correct categories according to action level 1 with sensitivities of 100 and 98·7%, and specificities of 98·1 and 98·2%, and according to action level 2 with sensitivities of 98·1 and 100%, and specificities of 100% for both sexes. Only 2% of the sample misclassified themselves into the wrong categories according to waist circumference action levels. In conclusion, people tend to underestimate their waist circumference, but the ‘Waist Watcher’ tape-measure offers advantages over self-reported home-assessed measurement, and may be used as a screening tool for self-classifying the risk of ill health through intra-abdominal fat accumulation.
(Received August 29 1997)
(Revised December 22 1997)
(Accepted January 27 1998)