ACCURACY AND RELIABILITY OF SELF-MEASUREMENT OF BODY GIRTHS

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Abstract
Because body fat distribution has been recognized as a disease risk factor, practical methods for the measurement of body girths are needed. In two groups of postmenopausal women aged 55–69 years in the upper midwestern United States, the authors examined the reliability and accuracy of self-measurement by mail questionnaire of waist, hip, upper arm, wrist and calf girths. intra-class correlations for waist girth were 0.96 when two self-measurements were compared and 0.93 when self-measurement was compared with technician measurement. Other intra-class correlations were at least 0.85 for repeat self-measurements except for wrist, which had an intra-class correlation of 0.66. For comparisons of self-measurement with technician measurement, intra-class correlations ranged from 0.71 for upper arm to 0.96 for hips. There was slight overestimation of waist girths and underestimation of hip girths when self-measurement was compared with technician measurement. Accuracy of self-measurement did not seem to vary according to age or educational status, but for hip, wrist, and calf girths it appeared that self-measurement underestimated technician measurement as girth size increased. For most girths, within-person variation in girth measurement also increased as girth size increased. Overall, girth self-measurement was both repeatable when re-ascertained by mail and accurate when compared with subsequent technician measurement.