How accurate are self-reported height, weight, and BMI among community-dwelling elderly Japanese?: Evidence from a...

The aims of this study are to investigate the accuracy of self-reported height, weight, and derived BMI of community-dwelling Japanese aged 70 and older, and to assess the concordance between report-based and measurement-based BMI categories.

We compared self-reported height and weight with physical measurements from data from a nationally representative sample (n = 1634).

Self-reported values were strongly correlated with measured values (Pearson's r: 0.92 and 0.89 for men and women, respectively, for height; 0.96 for both sexes for weight; 0.93 and 0.91 for men and women, respectively, for BMI). The differences in mean values were small. On average, height was overreported by 0.93 cm (SD = 2.48) for men and 1.23 cm (SD = 2.84) for women. Weight was underreported by 1.08 kg (SD = 2.55) for men and 0.88 kg (SD = 2.45) for women. BMI was underestimated by 0.68 kg/m(2) (SD = 1.16) for men and 0.79 kg/m(2) (SD = 1.49) for women. As age increases, height overreporting increased, particularly among women, but weight underreporting decreased for women. BMI underestimation increased for both sexes. Weighted kappa values showed a reasonably high concordance at 0.715 and 0.670 for men and women, respectively (P < 0.0001). Overweight (BMI 25.0 to 29.9) and obesity (BMI ≥ 30) prevalence rates were underestimated, with better specificity (range: 94.4-100%) than sensitivity (range: 59.3-65.1%).

The accuracy of self-reported height and weight is reasonably high among elderly Japanese, suggesting that the information can be used in epidemiological surveys. However, caution should be exercised for the oldest age group (age 85+), as the accuracy declined.