Trial Information

Recontacting Participants in the Observing Protein and Energy Nutrition Study: ReOPEN

NCI carries out extensive research and surveillance activities that rely on self-reported
dietary information from questionnaires and interviews. Although scientists have long
recognized that this information contains error, considerable uncertainty remains about its
structure. The interpretation of findings from NCI's nutritional epidemiology and
surveillance efforts is critically dependent on the assessment of dietary measurement error.
We evaluated such measurement error in the previously conducted Observing Protein and
Energy Nutrition Study (OPEN) conducted in 1999 and 2000. This study, the largest study of
its kind, used unbiased biomarkers of dietary intake (doubly labeled water for energy and
24-hour urinary nitrogen for protein) to assess measurement error in dietary assessment
methods commonly used in epidemiology and surveillance research around the world. The
landmark findings indicate that relative risk estimates in nutritional epidemiology may be
severely attenuated by the use of food frequency questionnaires and that the conventional
use of 24-hour dietary recalls as reference measurements may lead to severe underestimates
of the extent of this attenuation. Key questions remain regarding whether these findings
hold in diverse populations, for other dietary-report or physical activity instruments,
across varying nutrients and food groups, and how measurement error affects relative risks
in existing prospective cohorts. In light of the OPEN study findings, we would like to
re-contact participants, for whom we already have a wealth of nutritional biomarker data, in
order to assess the structure of measurement error with respect to two other self-reported
dietary assessment instruments: the food record and a food checklist-adjusted food
frequency questionnaire. Our intent is to evaluate whether these instruments might have
more favorable measurement error structure than the food frequency questionnaire, thereby
providing better tools for nutritional epidemiology.