Reproduciblity and Validity of a Semiquantitative Food Frequency Questionnaire

Abstract

The aim of this study was to evaluate the reproducibility and validity of a 61-item semiquantitative food frequency questionnaire used in a large prospective study among women. This form W88 administered twice to 173 particIpants at an interval of approximate'y one year (1980-1981), and four one-week diet records for each subject were collected during that period. Intraclass correlation coeffidents for nutrient intakes estimated by the one-week diet records (range = 0.41 for total Vitamin A without supplements to 0.79 for Vitamin B, with supplements) were similar to those computed from the questionnaire (range = 0.49 for total Vitamin A without 8upplements to 0.71 for sucrose), indicating that these methods were generally comparable with respect to reproducibility. With the exception of sucrose and total carbohydrate, nutilent Intakes from the diet records tended to correlate more strongly with those computed from the questionn&re after adjustment for total caloric Intake. Correlation coefficients between the mean calorie-adjusted intakes from the four one-week diet records and those from the questionna ire completed after the diet records ranged from 0.36 for Vitamin A without supplements to 0.75 for vitamin C with supplements. Overall, 48% of 8ubjects n the lowest quintile of calorie-Adjusted intake computed from the diet records were also in the lowest questionnaire quintile, and 74% were in the lowest one of two questionnaire quintiles. SImilarly, 49% of those in the highest diet record quintile were also in the highest questionnaire quintile, and 77% were In the highest one or two questionnafre quintiles. These data indicate that a simple self-administered dietary questionnaire can provide u8efuI information about indMdual nutrient intakes over a one-year penod.