REPRODUCIBILITY OF AN ITALIAN FOOD FREQUENCY QUESTIONNAIRE FOR CANCERSTUDIES - RESULTS FOR SPECIFIC FOOD ITEMS

To evaluate the reproducibility of a quantitative food frequency quest ionnaire (FFQ) used in a case-control study on cancer of the breast, o vary and digestive tract, we compared the result of a 98-item question naire administered twice at an interval of 3-10 months (median = 5.4 m onths) to 452 volunteers (144 males and 308 females, median age = 50 y ears) from three Italian provinces (Pordenone, Genoa and Forli). Spear man correlation coefficients (r) for intake frequency of 87 dietary it ems ranged from 0.35 (''chicken or turkey, boiled'') to 0.84 (''wine'' ). Most coefficients were between 0.60 and 0.80, only two being below 0.40 and five equal or above 0.80 (mean r = 0.59). The concordance of the two measurements tended to be somewhat better for alcoholic and no n-alcoholic beverages, bread, cereals and first courses, fruits and su mmary questions at the end of each section of the questionnaire than f or side dishes, sweets and desserts. Also, the reproducibility of 11 s ubjective questions, such as those concerning the amount of fat in sea soning and the intake of garlic or salt, seemed to be high. Age, sex, educational level of the volunteers and interval between the two FFQ d id not have a large or systematic impact on the concordance of the two measurements. In conclusion, the present study has shown a good level of reproducibility of our questionnaire and has provided a few import ant hints on ways of improving the description of various food items.