[BDSP. Notice produite par INIST-CNRS R0xCEDFA. Diffusion soumise à autorisation]. 1 Division of Public Health Sciences, Fred Hutchinson Cancer Research Center, Seattle, WA. 2 Biostatistics Research Branch, National Institute of Allergy and Infectious Diseases, Bethesda, MD. 3 Department of Nutritional Sciences, University of Wisconsin, Madison, Wl. 4 Medical Research Council Dunn Human Nutrition Unit, University of Cambridge, Cambridge, United Kingdom. 5 Department of Preventive Medicine, Feinberg School of Medicine, Northwestern University, Chicago, IL. 6 Department of Epidemiology, School of Public Health and Community Medicine, University of Washington, Seattle, WA. 7 Division of Research, Kaiser Permanente, Oakland, CA. 8 Department of Nutritional Sciences, College of Agriculture and Life Sciences, University of Arizona, Tucson, AZ. 9 Division of Prevention and Control, Arizona Cancer Center, Tucson, AZ. 10 Department of Preventive Medicine, College of Medicine, University of Tennessee Health Science Center, Memphis, TN. 11 Department of Epidemiology, Graduate School of Public Health, University of Pittsburgh, Pittsburgh, PA. 12 Department of Epidemiology, School of Public Health, University of North Carolina, Chapel Hill, NC. 13 School of Community Health, College of Urban and Public Affairs, Portland State University, Portland, OR. 14 Department of Obstetrics and Gynecology, Medical School, University of Wisconsin-Madison, Madison, Wl. 15 Department of Medicine, University of Massachusetts Medical Center, Worcester, MA. 16 Stanford Prevention Research Center, Stanford University, Palo Alto, CA. 17 Pfizer, Inc., New York, NY. Underreporting of energy consumption by self-report is well-recognized, but previous studies using recovery biomarkers have not been sufficiently large to establish whether participant characteristics predict misreporting. In 2004-2005,544 participants in the Women's Health Initiative Dietary Modification Trial completed a doubly labeled water protocol (energy biomarker), 24-hour urine collection (protein biomarker), and self-reports of diet (assessed by food frequency questionnaire (FFQ)), exercise, and lifestyle habits ; 111 women repeated all procedures after 6 months. Using linear regression, the authors estimated associations of participant characteristics with misreporting, defined as the extent to which the log ratio (self-reported FFQ/nutritional biomarker) was less than zero. Intervention women in the trial underreported energy intake by 32% (vs. 27% in the comparison arm) and protein intake by 15% (vs. 10%). Younger women had more underreporting of energy (p=0.02) and protein (p=0.001), while increasing body mass index predicted increased underreporting of energy and overreporting of percentage of energy derived from protein (p=0.001 and p=0.004, respectively). Blacks and Hispanics underreported more than did Caucasians. Correlations of initial measures with repeat measures (n=111) were 0.72,0.70,0.46, and 0.64 for biomarker energy, FFQ energy, biomarker protein, and FFQ protein, respectively. Recovery biomarker data were used in regression equations to calibrate self-reports ; the potential application of these equations to disease risk modeling is presented. The authors confirm the existence of systematic bias in dietary self-reports and provide methods of correcting for measurement error.