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

Schröder, Helmut, 1958-; Subirana Cachinero, Isaac; Gómez, Santiago Felipe

doi:http://dx.doi.org/10.1186/s12966-021-01169-w

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

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Schröder H, Subirana I, Wärnberg J, Medrano M, González-Gross M, Gusi N et al. Validity, reliability, and calibration of the physical activity unit 7 item screener (PAU-7S) at population scale. Int J Behav Nutr Phys Act. 2021 Jul 17;18(1):98. DOI: 10.1186/s12966-021-01169-w

Abstract

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. Results: The PAU-7S overestimated MVPA by 18%, compared to accelerometers (106.5 ± 77.0 vs 95.2 ± 33.2 min/day, respectively). A Cronbach alpha of 0.76 showed an acceptable internal consistency of the PAU-7S. Test-retest reliability was good (ICC 0.71 p < 0.001). Spearman correlation and ICC coefficients of MVPA derived by the PAU-7S and accelerometers increased from 0.31 to 0.62 and 0.20 to 0.62, respectively, after calibration of the PAU-7S. Between-methods concordance improved from a weighted kappa of 0.24 to 0.50 after calibration. A slight reduction in ICC, from 0.62 to 0.60, yielded good predictive validity. Multiple linear regression models showed an inverse association of MVPA with standardized body mass index (β - 0.162; p < 0.077) and waist to height ratio (β - 0.010; p < 0.014). All validity dimensions were somewhat stronger in boys compared to girls. Conclusion: The PAU-7S shows a good test-retest reliability and acceptable internal consistency. All dimensions of validity increased from poor/fair to moderate/good after calibration. The PAU-7S is a valid instrument for measuring MVPA in children and adolescents.