Percent Energy from Fat Screener: Validity Results

Performance of a Short Instrument to Estimate Usual Dietary Intake of Percent Calories from Fat
Thompson FE, Kipnis V, Subar AF, Schatzkin A, Potischman N, Kahle L, McNutt S
National Cancer Institute; Information Management Services, Inc.; Westat, Inc
Presented at the Third International Conference on Dietary Assessment Methods, May 1998

Our objective was to develop and test a short instrument to estimate the individual's usual dietary intake of percent calories from fat (pcalfat). Data used for development of the instrument were two non-consecutive 24-hour dietary recalls (24-h) collected from a nationally representative sample of the US in the US Department of Agriculture's 1994-95 Continuing Surveys of Food Intakes by Individuals. All foods consumed in the survey were categorized into 195 mutually exclusive food groups. For each survey individual and food group, the number of times that food group was reported over the two days was computed. Stepwise multiple regression was used to select a small number (15) of food groups most predictive of pcalfat and to develop gender-specific scoring algorithms. Participants in the Calibration Study of the National Institutes of Health-American Association of Retired Persons Diet and Health Study, ages 50 to 69 living in 8 areas of the US, who had in the past year completed two telephone-administered non-consecutive 24-h and a food frequency questionnaire (FFQ), were asked to complete by mail the pcalfat screener. Of the 657 screeners mailed, 473 (72%) were returned; 412 answered all questions and had completed two 24-h. Mean pcalfat estimates were: 30.6 (24- h), 31.6 (screener), and 29.6 (FFQ) for men, and 31.6 (24-h), 29.8 (screener), and 29.4 (FFQ) for women. For men, the estimated correlation adjusted for measurement error between the screener and truth was 0.62, and between the FFQ and truth was 0.78. For women, the estimated correlation between the screener and truth was 0.69, and between the FFQ and truth was 0.49. We conclude that this pcalfat screener may be a useful tool for some populations in situations when a more detailed assessment is not warranted.