Accuracy of anthropometric measurements by general practitioners in overweight and obese patients

We recently showed that abdominal obesity measurements (waist and hip circumference, waist-to-hip ratio) were inaccurate when performed by general practitioners (GPs). We hypothesise that measurement error could be even higher in overweight and obese patients due to difficulty in locating anatomical landmarks. We aimed to estimate GPs' measurement error of general (weight, height and body mass index (BMI)) and abdominal obesity measurements across BMI subgroups.

This cross-sectional study involved 26 GPs in Geneva, Switzerland. They were asked to take measurements on 20 volunteers within their practice. Two trained research assistants repeated the measures after the GPs ("gold standard"). The proportion of measurement error was computed by comparing the GPs' values (N = 509) to the average value of two measurements taken in turn by the research assistants and stratified by BMI subgroup (normal/underweight: <25 kg/m², overweight: 25 ≤ BMI < 30 kg/m², obese: ≥30 kg/m²).

General obesity measurements were less prone to measurement error than abdominal obesity measurements, regardless of the BMI subgroup. The proportions of error increased across BMI subgroups (except for height), and were particularly high for abdominal obesity measurements in obese patients.

Abdominal obesity measurements are particularly inaccurate when GPs use these measurements to assess overweight and obese patients. These findings add further strength to recommendations for GPs to favour use of general obesity measurements in daily practice, particularly when assessing overweight or obese patients.