Biomarker-Calibrated Activity-Related Energy Expenditure Estimation

• Activity Number: 640
• Type: Topic Contributed
• Date/Time: Thursday, August 2, 2012 : 10:30 AM to 12:20 PM
• Sponsor: Biometrics Section
• Author(s): Ross Prentice*+
• Companies: Fred Hutchinson Cancer Research Center
• Keywords: Biomarker ; Measurement error ; Physical activity ; Regression calibration ; Self-report ; Systematic bias

Abstract

Ross L Prentice, Division of Public Health Sciences, Fred Hutchinson Cancer Research Center, Seattle, WA A measurement model is considered for physical activity that involves a classical measurement model for an objective measure, and a more general model for corresponding self-reports. This model is applied to activity-related energy expenditure (AREE) using data from 450 women from the Women's Health Initiative, with objective measure defined as total energy expenditure from a doubly labeled water assessment procedure minus resting energy expenditure from indirect calorimetry. There were 3 corresponding self-report assessments: an Arizona Activity Frequency Questionnaire, a 7-day Physical Activity Recall, and a WHI Personal Habits Questionnaire from which AREE was computed. Calibration equations from regressing [log AREE-biomarker] on [log AREE self-report] revealed that self-report alone explained only small amounts of the biomarker variance with each of the self-report assessments, whereas this percentage was considerably larger when BMI, age and ethnicity were added to the regression model. Methods for relating calibrated AREE to disease risk will also be presented.