Video instructions improve accuracy of self-measures of waist circumference compared with written instructions

School of Pharmacy and Life Sciences, Robert Gordon University, St Andrew Street,Aberdeen AB25 1HG, UKSubmitted 24 August 2010: Accepted 14 February 2011: First published online 31 March 2011AbstractObjective: To determine whether video-based instructions improve the accuracy ofself-measures of waist and hip circumference compared with written instructions.Design: Population-based, cross-sectional study. Self-measurements of waist cir-cumference (WC) and hip circumference (HC) of fifty-seven participants randomlyallocated to receive either written instruction or video instruction were comparedwith those of a trained technician.Setting: Aberdeen, Scotland, and Brussels, Belgium, between February and April2010.Subjects: Adultsaged18–62yearswithahighlevel ofEnglish languageand nopriortraining in anthropometry.Results: WC was significantly overestimated by the written method (1?75cm bias;P50?007) but not the video method (0?95cmbias; P50?239). HC was significantlyunderestimated in both written (20?35cm bias; P50?009) and video methods(20?75cm bias; P50?046). Reliability was not significantly affected by age, sex,BMI or WC. Bland–Altman plots demonstrated wide limits of agreement for WC(26?83, 6?08cm for written method; 210?14, 6?72cm for video method) and HC(212?85, 1?60cm for written method; 210?82, 2?50cm for video method).Conclusions: Video technology can support more accurate self-measurements ofanthropometric datain epidemiological studies. Further research iswarranted usinglarger and more heterogeneous samples in order that results can be generalised.KeywordsAnthropometryMeasurementVideo instructionObesity is becoming increasingly prevalent worldwide.Historically, BMI and waist:hip ratio (WHR) have beenused as indices of obesity and related disease risk inepidemiological studies