METHODOLOGY OF A 2-STEP QUANTIFIED NUTRITIONAL QUESTIONNAIRE AND ITS EFFECT ON RESULTS

The effects of methodology on the results of epidemiologic studies tha t involve collection of nutritional data, especially those involving l ong-term-onset illnesses such as cancer, have not yet been carefully e valuated. We present methodological features of a quantitative dietary history and physical activity questionnaire and discuss their contrib ution to the final results. The results of our analysis are as follows : I) Forty-seven percent of the population consumed >100 food items ye arly. 2) The mean number of calories contributed by items eaten less t han once a week exceeded 200 kcal/day in 50% of intewiewees. 3) Sevent y-six percent of the patients had undergone dietary changes during the course of adult life. Of the 379 individuals who reported no changes when asked general questions, 61.8% reported changes when asked specif ically about each food item in the questionnaire. 4) Physical activity was significantly correlated with mean daily energy intake (r = 0.208 , p < 0.001). We conclude that certain methodological features of ques tionnaires, such as extensive listing of food items, precise documenta tion of food quantity, inquiries about former earing habits, and inclu sion of questions about physical activity, increase accuracy in evalua tions of dietary habits. Our analysis provides practical information f or future planning of nutritional questionnaires.