Effect of the day and the number of days of application on reproducibility of a questionnaire to assess the food intake in schoolchildren.

INTRODUCTION The Food Intake and Physical Activity of School Children (Web-CAAFE) is an online questionnaire developed to monitor the diet and physical activity of Brazilian schoolchildren. The study aimed to evaluate the effect of the day of the week and the number of applications on Web-CAAFE reproducibility. METHODS Schoolchildren in grades 2 to 5 of two municipal schools in Florianopolis (n = 197) filled out the Web-CAAFE twice in the same day, of which 113 filled out the instrument in three non-consecutive days. The analysis was performed using the intraclass correlation (ICC) and logistic regression was used to evaluate the factors associated with poor reproducibility. RESULTS The reproducibility of the questionnaire was significantly lower for children who filled out their consumption mostly on weekends in relation to weekdays (OR = 2.93; p = 0.045), and was significantly better in girls in relation to boys (OR = 0.29; p< 0.001). Higher CCI was observed on the second and third day of Web-CAAFE application in relation to the first day. These results are relevant for planning future studies that use dietary assessment instruments in children, especially on evaluation of their validity and reproducibility. CONCLUSIONS The results suggest that at least two days provides acceptable reproducibility results of the Web-CAAFE and that the weekend recall may reduce the reproducibility.