Validity of self-reported height and weight in a Japanese workplace population

OBJECTIVE: To assess the validity of self-reported height and weight in a Japanese workplace population, and to examine factors associated with the validity of self-reported weight. DESIGN: Comparison of self-reported height and weight with independent measurement. SUBJECTS: In total, 4253 men and 1148 women aged 35-64 y (mean measured body mass index (BMI): 23.3 kg/m² in men, 21.9 kg/m² in women) were included in the study. MEASUREMENTS: Self-reported height and weight were obtained by a self-administered questionnaire. Measured height and weight were based on annual health checkups. Sex, age, measured BMI, and the presence of hypertension, diabetes, and hyperlipidemia were examined as potential factors associated with the accuracy of self-reported weight. RESULTS: Self-reported height and weight were highly correlated with measured height and weight for men and women (Pearson's r for men and women: 0.979 and 0.988 in height, 0.961 and 0.959 in weight, 0.943 and 0.950 in BMI, respectively). For men, mean differences±2 s.d. of height and weight were 0.078±2.324 cm and -0.034±5.012 kg, respectively, and for women 0.029±1.652 cm and 0.024±4.192 kg, respectively. The prevalence of obesity with BMI ≥25 kg/m² based on self-reported data (23.6 and 11.5% for men and women, respectively) was slightly smaller than that based on measured data (24.9 and 12.4%, respectively). Specificity and sensitivity, however, were quite high for both men and women (sensitivity was 85.8 and 85.2%, and specificity was 97.0 and 98.9%, respectively). The subjects with higher measured BMI significantly underestimated their weight compared with those with smaller BMI after adjustments for age in men and women. Furthermore, the presence of diabetes in men and age in women affected self-reported weight. Neither the presence of hypertension nor hyperlipidemia was associated with reporting bias. CONCLUSION: The self-reported height and weight were generally reliable in the middle-aged employed Japanese men and women. However, it should be remembered that self-reported weight was biased by actual BMI and affected by age and the presence of diabetes.