Validation of self-reported figural drawing scales against anthropometric measurements in adults

Objective: The aim of the present study was to validate figural drawing scales depicting extremely lean to extremely obese subjects to obtain proxies for BMI and waist circumference in postal surveys. Design: Reported figural scales and anthropometric data from a large population-based postal survey were validated with measured anthropometric data from the same individuals by means of receiver-operating characteristic curves and a BMI prediction model. Setting: Adult participants in a Scandinavian cohort study first recruited in 1990 and followed up twice since. Subjects: Individuals aged 38-66 years with complete data for BMI (n 1580) and waist circumference (n 1017). Results: Median BMI and waist circumference increased exponentially with increasing figural scales. Receiver-operating characteristic curve analyses showed a high predictive ability to identify individuals with BMI > 25.0 kg/m(2) in both sexes. The optimal figural scales for identifying overweight or obese individuals with a correct detection rate were 4 and 5 in women, and 5 and 6 in men, respectively. The prediction model explained 74% of the variance among women and 62% among men. Predicted BMI differed only marginally from objectively measured BMI. Conclusions: Figural drawing scales explained a large part of the anthropometric variance in this population and showed a high predictive ability for identifying overweight/obese subjects. These figural scales can be used with confidence as proxies of BMI and waist circumference in settings where objective measures are not feasible.