OBSERVER VARIATION IN MEASUREMENTS OF WAIST HIP RATIO AND THE ABDOMINAL SAGITTAL DIAMETER

In an out-patient weight loss study of 63 patients (54 female, 9 male) , 53 completed a 16 week treatment with a low calorie diet and a 9 g/d ay fibre supplement. In these 53 patients, the average weight loss was 8.3 kg (s.e.m. 0.8). Waist-hip ratio (WHR) and abdominal sagittal dia meter (SagD) were measured as indicators of fat distribution and visce ral adipose tissue (visceral AT) was estimated by anthropometric compu terized tomography calibrated equations. Four observers measured WHR a nd SagD ten times in eight patients. Two dietitians examined the patie nts throughout the clinical trial at weeks 0, 4, 8 and 16. Furthermore , two physicians examined the patients at week 12 in the trial. Two- a nd three-way analyses of variance were performed to estimate the contr ibution of single factors to the total variance. The contribution of o bservers, 3.2% and 3.8%, respectively, was of the same magnitude as th e error variance (2.9% and 4.8% respectively) which is a measure of th e intra-observer variation. The two dietitians had very similar record ings and contributed only 0.3% and 0.9% to the total variance for WHR and SagD, respectively. The contributions of the two physicians to the total variance were 0.0% for WHR and 0.4% for SagD. It is concluded t hat there is no need to use several observers or repeated measurements of waist, hip and SagD in clinical anti-obesity trials.