Reliability and Validity of a Questionnaire for Physical Activity Assessment in South American Children and Adolescents: The SAYCARE Study

ObjectiveThe objective of this article is to test the reliability and validity of the new and innovative physical activity (PA) questionnaire. MethodsSubsamples from the South American Youth/Child Cardiovascular and Environment Study (SAYCARE) study were included to examine its reliability (children: n=161; adolescents: n=177) and validity (children: n=82; adolescents: n=60). The questionnaire consists of three dimensions of PA (leisure, active commuting, and school) performed during the last week. To assess its validity, the subjects wore accelerometers for at least 3 days and 8h/d (at least one weekend day). The reliability was analyzed by correlation coefficients. In addition, Bland-Altman analysis and a multilevel regression were applied to estimate the measurement bias, limits of agreement, and influence of contextual variables. ResultsIn children, the questionnaire showed consistent reliability (=0.56) and moderate validity (=0.46), and the contextual variable variance explained 43.0% with -22.9min/d bias. In adolescents, the reliability was higher (=0.76) and the validity was almost excellent (=0.88), with 66.7% of the variance explained by city level with 16.0min/d PA bias. ConclusionsThe SAYCARE PA questionnaire shows acceptable (in children) to strong (in adolescents) reliability and strong validity in the measurement of PA in the pediatric population from low- to middle-income countries.