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Epidemiology and Genomics Research Program

Observing Protein & Energy Nutrition (OPEN) Study

What is the OPEN Study?

The Observing Protein and Energy Nutrition (OPEN) Study was an NCI-sponsored study designed to assess dietary measurement error by comparing results from self-reported dietary intake data with four dietary biomarkers: doubly labeled water and urinary nitrogen, sodium, and potassium. The study was conducted from July 1999 to March 2000 and included 484 men and women, aged 40-69 years old, living in Montgomery County, Maryland.

View a list of selected publications that have used data from the OPEN Study

Subar AF, Midthune D, Tasevska N, Kipnis V, Freedman LS. Checking for completeness of 24-h urine collection using para-amino benzoic acid not necessary in the Observing Protein and Energy Nutrition studyEur J Clin Nutr. 2013 Aug;67(8):863-7.

Cook CM, Subar AF, Troiano RP, Schoeller DA. Relation between holiday weight gain and total energy expenditure among 40- to 69-y-old men and women (OPEN study)Am J Clin Nutr. 2012 Mar;95(3):726-31.

Kirkpatrick SI, Midthune D, Dodd KW, Potischman N, Subar AF, Thompson FE. Reactivity and its association with body mass index across days on food checklistsJ Acad Nutr Diet. 2012 Jan;112(1):110-8.

Bradley DP, Johnson LA, Zhang Z, Subar AF, Troiano RP, Schatzkin A, Schoeller DA. Effect of smoking status on total energy expenditureNutr Metab (Lond). 2010;7:81.

Millen AE, Tooze JA, Subar AF, Kahle LL, Schatzkin A, Krebs-Smith SM. Differences between food group reports of low-energy reporters and non-low-energy reporters on a food frequency questionnaireJ Am Diet Assoc. 2009 Jul;109(7):1194-203.

Yanetz R, Kipnis V, Carroll RJ, Dodd KW, Subar AF, Schatzkin A, Freedman LS. Using biomarker data to adjust estimates of the distribution of usual intakes for misreporting: application to energy intake in the US populationJ Am Diet Assoc. 2008 Mar;108(3):455-64; discussion 464.

Tooze JA, Schoeller DA, Subar AF, Kipnis V, Schatzkin A, Troiano RP. Total daily energy expenditure among middle-aged men and women: the OPEN StudyAm J Clin Nutr. 2007 Aug;86(2):382-7.

Lissner L, Troiano RP, Midthune D, Heitmann BL, Kipnis V, Subar AF, Potischman N. OPEN about obesity: recovery biomarkers, dietary reporting errors and BMIInt J Obes (Lond). 2007 Jun;31(6):956-61.

Freedman LS, Midthune D, Carroll RJ, Krebs-Smith S, Subar AF, Troiano RP, Dodd K, Schatzkin A, Bingham SA, Ferrari P, Kipnis V. Adjustments to improve the estimation of usual dietary intake distributions in the populationJ Nutr. 2004 Jul;134(7):1836-43.

Tooze JA, Subar AF, Thompson FE, Troiano R, Schatzkin A, Kipnis V. Psychosocial predictors of energy underreporting in a large doubly labeled water studyAm J Clin Nutr. 2004 May;79(5):795-804.

Schatzkin A, Kipnis V, Carroll RJ, Midthune D, Subar AF, Bingham S, Schoeller DA, Troiano RP, Freedman LS. A comparison of a food frequency questionnaire with a 24-hour recall for use in an epidemiological cohort study: results from the biomarker-based Observing Protein and Energy Nutrition (OPEN) studyInt J Epidemiol. 2003 Dec;32(6):1054-62.

Kipnis V, Subar AF, Midthune D, Freedman LS, Ballard-Barbash R, Troiano RP, Bingham S, Schoeller DA, Schatzkin A, Carroll RJ. Structure of dietary measurement error: results of the OPEN biomarker studyAm J Epidemiol. 2003 Jul 01;158(1):14-6.

Kipnis V, Subar AF, Schatzkin A, Midthune D, Troiano RP, Schoeller DA, Bingham S, Freedman LS. Kipnis et al. Respond to "OPEN Questions". Am J Epidemiol. 2003 Jul 01;158:25-26.

Subar AF, Kipnis V, Troiano RP, Midthune D, Schoeller DA, Bingham S, Sharbaugh CO, Trabulsi J, Runswick S, Ballard-Barbash R, Sunshine J, Schatzkin A. Using intake biomarkers to evaluate the extent of dietary misreporting in a large sample of adults: the OPEN studyAm J Epidemiol. 2003 Jul 01;158(1):1-13.

How did the OPEN Study assess the FFQ and 24-Hour Recall?

Over the course of the study, OPEN participants completed two Food Frequency Questionnaires (FFQ), two 24-recall interviews, and filled out several other health-related questionnaires. They were dosed with doubly labeled water (a biomarker used for measuring energy expenditure), provided several spot urine samples to complete the doubly labeled water assessment, completed two 24-hour urine collections and had their height and weight measured. Investigators analyzed the 24-hour urines for several nutrients: nitrogen, sodium and potassium, biomarkers that measure protein, sodium, and potassium intakes, respectively. The questionnaires and samples allowed study investigators to compare what participants said they ate and drank against the objective evidence provided by the biomarkers and thus, to get a better sense of the extent and nature of error in the FFQs and 24-hour recalls.

Multifactor Screener in the OPEN Study

The Multifactor Screener may be useful to assess approximate intakes of fruits and vegetables, percentage energy from fat, and fiber. The screener asks respondents to report how frequently they consume foods in 16 categories. The screener also asks one question about the type of milk consumed. No portion size questions are asked. This screener does not attempt to assess total diet.

The foods selected to compose the screener were identified through an analysis of USDA's 1994-96 Continuing Survey of Food Intakes of Individuals (CSFII), a nationally representative survey of the food intakes of the US population available from the USDA's Food Surveys Research Group. NCI's Risk Factor Assessment Branch staff used stepwise regression to identify the food groups that would best predict the three dietary exposures. Some of the foods in the screener predict all three exposures; some predict only one or two of the exposures.

The Multifactor Screener was self-administered in the OPEN study. An interviewer-administered version was used in the 2000 NHIS Cancer Control Supplement.

The process of scoring the individual response data is described in Scoring Procedures. A SAS program is included. Guidelines for the appropriate uses of the screener-estimated dietary intakes are the same as those described in Uses of Screener Estimates in the 2000 NHIS Cancer Control Supplement. Validation data for the Multifactor Screener in OPEN is presented in Validation Results. The data dictionary for the screener is available in RTF [58KB] and PDF [67KB] formats.