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

Helmut Schröder,Santiago F Gómez,Nicolás Terrados,María Medrano,Clara Sistac-Sorigué,Estefanía Herrera-Ramos,Marta Segú,Fabio Jiménez-Zazo,Elena Marín-Cascales,María Del Mar Bibiloni,Idoia Labayen,Josep A Tur,Clara Homs,Isaac Subirana,Susana Aznar,Augusto G Zapico,Susana Pulgar,Miguel González Valeiro ,Jesús Sánchez‐Gómez ,Narcís Gusi ,Alicia García-Álvarez ,Marta Sevilla-Sánchez ,Lluís Serra‐Majem ,Juan Carlos Benavente-Marín ,Francisco Javier Barón-López ,Marcela González‐Gross ,Julia Wärnberǵ ,Pedro E Alcaráz

doi:10.1186/s12966-021-01169-w

Abstract

BackgroundValidation 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.MethodsA 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.ResultsThe 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.ConclusionThe 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.Trial registrationTrial registration numberISRCTN34251612.

Highlights

Physical activity (PA) is associated with favorable mental and physical health in children and adolescents [1,2,3]
Spearman correlation and intra-class correlation (ICC) coefficients of moderate and vigorous physical activity (MVPA) derived by the Physical Activity Unit 7 item Screener (PAU-7S) and accelerometers increased from 0.31 to 0.62 and 0.20 to 0.62, respectively, after calibration of the PAU-7S
The PAU-7S is a valid instrument for measuring MVPA in children and adolescents

Summary

Introduction

Physical activity (PA) is associated with favorable mental and physical health in children and adolescents [1,2,3]. The World Health Organization (WHO) recommends at least 60 min per day of moderate and vigorous physical activity (MVPA) for children aged 5 to 17 years [4]. The administration of PA questionnaires is a cheaper and more feasible method, albeit less accurate, to meet the challenge of measuring PA in children and adolescents These questionnaires vary in their design and structure (e.g., recorded periods of PA range from 1 day to 1 year) [7] and have been validated in specific population subgroups, which limits the transferability of results. Brief PA questionnaires are needed to readily identify children not meeting the WHO PA recommendations and assist in PA counseling [13] For this reason we developed the Physical Activity Unit 7-day Screener (PAU-7S), a brief PA questionnaire developed to measure PA in children and adolescents. The effect of linear calibration on PAU-7S validity was tested

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