Development and validity of a questionnaire to test the knowledge of primary care personnel regarding nutrition in obese adolescents

BACKGROUND: In light of its epidemic proportions in developed and developing countries, obesity is considered a serious public health issue. In order to increase knowledge concerning the ability of health care professionals in caring for obese adolescents and adopt more efficient preventive and control measures, a questionnaire was developed and validated to assess non-dietitian health professionals regarding their Knowledge of Nutrition in Obese Adolescents (KNOA). METHODS: The development and evaluation of a questionnaire to assess the knowledge of primary care practitioners with respect to nutrition in obese adolescents was carried out in five phases, as follows: 1) definition of study dimensions 2) development of 42 questions and preliminary evaluation of the questionnaire by a panel of experts; 3) characterization and selection of primary care practitioners (35 dietitians and 265 non-dietitians) and measurement of questionnaire criteria by contrasting the responses of dietitians and non-dietitians; 4) reliability assessment by question exclusion based on item difficulty (too easy and too difficult for non-dietitian practitioners), item discrimination, internal consistency and reproducibility index determination; and 5) scoring the completed questionnaires. RESULTS: Dietitians obtained higher scores than non-dietitians (Mann–Whitney U test, P < 0.05), confirming the validity of the questionnaire criteria. Items were discriminated by correlating the score for each item with the total score, using a minimum of 0.2 as a correlation coefficient cutoff value. Item difficulty was controlled by excluding questions answered correctly by more than 90% of the non-dietitian subjects (too easy) or by less than 10% of them (too difficult). The final questionnaire contained 26 of the original 42 questions, increasing Cronbach’s α value from 0.788 to 0.807. Test-retest agreement between respondents was classified as good to very good (Kappa test, >0.60). CONCLUSION: The KNOA questionnaire developed for primary care practitioners is a valid, consistent and suitable instrument that can be applied over time, making it a promising tool for developing and guiding public health policies.