Validation of ketogenic diet adherence questionnaire: Keto-check

The ketogenic diet is a therapeutic option to control drug-resistant epileptic seizures and has difficult compliance standards due to adverse effects, psychosocial factors, or dietary restriction.

To create and validate a ketogenic diet compliance questionnaire.

Methodological study, convergent care. The instrument was analyzed (construct validation) by five judges during two cycles of the Delphi technique. The judges assessed the relevance and clarity by using the Likert scale with three levels and made suggestions. The validation of the instrument was calculated using the agreement rate and content validity index (CVI). The application by two nutritionists made it possible to test reproducibility using the Kappa coefficient. When comparing the classification with a template developed by the health professionals who cared for the patients in question, the Pearson correlation and Fisher exact tests were used. For the reliability test, self-applied data were collected and evaluated using Cronbach Alpha coefficient.

The questionnaire initially created with 11 multiple choice questions on a Likert scale was reduced to 10 questions with an agreement rate and the CVI classified as excellent after two rounds with judges. In the application of the tool, a kappa of 0.6087 was obtained, a Pearson that showed no significant difference between evaluators and a Cronbach α of 0.6483, with substantial consistency.

This work resulted in the creation of an unprecedented and reliable questionnaire on adherence to the national ketogenic diet. Further studies should be performed to extrapolate the use of this questionnaire in different populations.