Use of accelerometer data in prediction equations for capturing implausible dietary intakes in adolescents.

BACKGROUND: Reporting errors have been quantified in epidemiologic studies by comparing reported intakes with predicted energy requirements (pERs). Several studies lacking measures of physical activity level (PAL) assigned low-active levels to obtain pERs.
OBJECTIVE: We applied objective physical activity measures to current methods to quantify dietary reporting errors and compared associations with anthropometric and dietary variables among plausible and implausible reporters.
DESIGN: This study included 2868 adolescents with an average age of 13 y. Three-day dietary records, accelerometers, and dual-energy X-ray absorptiometry were used to assess diet, activity, and body composition, respectively. Three variations of physical activity coefficients were used: 1) assigning low physical activity coefficients (PA(low)), 2) calculating PAL values (PA(PAL)), and 3) applying minutes of moderate-to-vigorous physical activity (PA(MVPA)).
RESULTS: Of the total participants, 51.5%, 51.8%, and 37.1% of the PA(low), PA(PAL), and PA(MVPA) groups, respectively, were classified as underreporters, and 40.8%, 37.9%, and 42.4% of the respective groups were classified as plausible reporters. Underreporters had a higher body mass index, body fat, and waist circumference than did plausible reporters (P < 0.001 for all). Overreporters had a lower weight and body fat than did plausible reporters (P < 0.001 for all). Underreporters reported lower dairy and calcium intakes than did plausible reporters; the results were attenuated with adjustment for total energy.
CONCLUSION: Accounting for objective physical activity measures to quantify reporting errors resulted in different and potentially more reasonable proportions of implausible reporters.