Validity, reliability, and calibration of the physical activity unit 7 item screener (PAU-7S) at population scale

Background: Validation of self-reported tools, such as physical activity (PA) questionnaires, is crucial. The aim of this study was to determine test-retest reliability, internal consistency, and the concurrent, construct, and predictive validity of the short semi-quantitative Physical Activity Unit 7 item Screener (PAU-7S), using accelerometry as the reference measurement. The effect of linear calibration on PAU-7S validity was tested. Methods: A randomized sample of 321 healthy children aged 8–16 years (149 boys, 172 girls) from the nationwide representative PASOS study completed the PAU-7S before and after wearing an accelerometer for at least 7 consecutive days. Weight, height, and waist circumference were measured. Cronbach alpha was calculated for internal consistency. Test-retest reliability was determined by intra-class correlation (ICC). Concurrent validity was assessed by ICC and Spearman correlation coefficient between moderate to vigorous PA (MVPA) derived by the PAU-7S and by accelerometer. Concordance between both methods was analyzed by absolute agreement, weighted kappa, and Bland-Altman statistics. Multiple linear regression models were fitted for construct validity and predictive validity was determined by leave-one-out cross-validation.

PASOS study has been funded mainly by Fundación PROBITAS and Gasol Foundation. Additional funds were received from the Barça Foundation, Banco Santander, Grupo IFA, Viena and Fundación Deporte Jóven, grant of support to research groups number 35/2011 (Balearic Islands Gov) and EU COST Action CA16112. J.A.T. and M.M.B. are funded by the official funding agency for biomedical research of the Spanish government, Institute of Health Carlos III (ISCIII), which is cofunded by the 333 European Regional Development Fund (CIBEROBN CB12/03/30038). PASOS has the institutional support of Spain’s Ministry of Education and Vocational Training, the Ministry of Health, Consumption and Social Welfare through the Spanish Agency for Food Safety and Nutrition (ASEAN), the High Commission against Child Poverty, the High Sports Council, the General College of Professional Associations of Physical Education and Sports, and the Departments of Education and/or Health and/or Sports of Spain’s 17 autonomous regions. The CIBERESP and the CIBEROBN are initiatives of the Institute of Health Carlos III, Madrid, Spain.