Objective: Diet is an important determinant of health outcomes, but physicians have few ways to identify persons with suboptimal diets. The purposes of this study were to examine the reproducibility of a short dietary assessment questionnaire (PrimeScreen) and to compare its results with those of a longer food frequency questionnaire and with plasma levels of selected nutrients.
Design: Each subject completed two PrimeScreen questionnaires at an interval of 2 weeks and one full length, 131-item, semiquantitative food frequency questionnaire (SFFQ), and had a sample of blood drawn. We compared the PrimeScreen with two reference standards, the SFFQ and plasma levels of selected nutrients.
Setting: A large managed care organization in New England.
Subjects: A total of 160 men and women, aged 19-65 years, participated.
Results: For foods and food groups, the mean correlation coefficient (r) was 0.70 for reproducibility and 0.61 for comparability with the SFFQ. For nutrients, the mean r was 0.74 for reproducibility and 0.60 for comparability with the SFFQ. No substantial differences were evident by sex, race, body mass index, occupation or education. Correlation coefficients for the comparison of vitamin E, beta-carotene and lutein/zeaxanthin intakes from the PrimeScreen with plasma levels were 0.33, 0.43 and 0.43, respectively. These values were similar to those comparing the SFFQ with plasma levels. The median time to complete PrimeScreen was 5 min; 87% of participants required fewer than 10 min.
Conclusions: A quick way to assess quality of diet among adults, PrimeScreen has adequate reproducibility and its results compare well with a longer food frequency questionnaire and biomarkers.