Development and content validity of an instrument for assessing the motivation for weight loss in adolescents with overweight and obesity

Objective To develop and validate the content of an instrument for assessing the motivation for weight loss in adolescents with overweight and obesity. Methods The development and validation of the instrument were conducted in five stages, for which two systematic reviews were conducted. The first one, for the identification of questionnaires assessing the motivation for weight loss, included six studies and contributed to the selection of the domains for the instrument. The second one, conducted to identify the motivations for weight loss in adolescents with overweight and/or obesity, included six studies and contributed to the selection of 17 motivations included in the initial version of the instrument. The motivations most commonly identified were: having better health, improving my appearance, improving my self-esteem and avoiding bullying. The content validity was confirmed by a committee of 12 experts from the areas of nutrition, endocrinology, psychology, and physical education. Based on these evaluations, the content validity index was calculated. Only the items with a content validity index >0.80 for practical relevance were held in the instrument. Results Five of the 17 motivations included in the initial version of the instrument were excluded because they had content validity index <0.80 for practical relevance. Of the 12 items held in the instrument, five were revised by experts in order to standardize wording and make the language more appropriate for adolescents. Experts categorized the items into the health, personal satisfaction, appearance and social domains. Conclusions This is the first instrument assessing the motivation for weight loss in adolescents with overweight and obesity in Brazil. The content validity evaluation by the panel of experts provided more practical relevance, as well as contributed to a better presentation of the items. Further psychometric testing is needed to determine reliability and construct validity of the instrument.