Validity and Utility of Self-Reported Weight Gain Since Age 20 in a 30-Year-Old Japanese Working Population

OBJECTIVES: We examined the validity of a questionnaire item on self-reported weight gain of ≥ 10 kg since age 20 among Japanese workers undergoing occupational health examinations. In addition, we performed the utility analysis to examine whether the associations with metabolic components at age 30 differ when using self-reported weight gain versus objectively measured weight gain as the exposure variable. METHODS: Participants were 6,272 men and 2,055 women aged 30 with objectively measured body weight data at ages 20 and 30. Weight gain (≥ 10 kg vs. < 10 kg) was defined using both self-reported and objectively measured data. The validity of the questionnaire item on self-reported weight gain was assessed using objectively measured weight gain as the reference standard. To evaluate its utility, we used modified Poisson regression to examine the associations with cardiometabolic components at age 30, separately for men and women, and compared these associations between the two exposure definitions: self-reported and objectively measured weight gain. RESULTS: At age 30, the sensitivity, specificity, and positive predictive value were 80.1%, 79.7%, and 52.9% in men, and 73.3%, 89.1%, and 48.5% in women, respectively. Associations of self-reported weight gain of ≥10 kg with cardiometabolic components at age 30 were similar in magnitude to those based on objectively measured weight gain. CONCLUSIONS: The self-reported questionnaire item showed acceptable validity and may serve as a practical alternative when historical body weight data are unavailable.