Reproducibility and Validity of the Food Frequency Questionnaire Methodology in an Urban Middle Income Group Community of Delhi, India

Abstract

The food frequency questionnaire (FFQ) method is utilized as a tool in epidemiological studies in which evidence is sought for an association of diet in etiology of a disease. Limited studies have been undertaken to assess the reproducibility of the FFQ methodology in Indian situation. The present study was conducted in an urban middle-income population of Delhi, India. The data on pattern of consumption of food items in standard food groups was collected from 169 subjects, utilizing a pre-tested semi-structured FFQ (Phase I). The consumption pattern of food items in the major food groups was also assessed prospectively for 7 days by the 24-hr dietary recall methodology in each subject. The data was collected again utilizing the similar methodology and tools from the same study subjects after 12 months (Phase II). Reproducibility and validity of the FFQ was assessed by calculating percent agreement between data of Phase I and Phase II utilizing statistical tests. Results revealed that there was a perfect agreement (100% agreement) for the food group i) cereals, ii) fats and oils, and iii) sugar and jaggery. A very good agreement (75-100%) for the food groups i) pulses, ii) green leafy vegetables, iii) fruits, iv) milk products, v) eggs, and vi) flesh foods. Only a good agreement (50 – 75%) was found for the food groups i) roots and tubers, ii) other vegetables, and iii) milk. None of the food groups had fair or poor agreement between the Phase I and Phase II.