title: Criterion validity of the Physical Activity Questionnaire for Schoolchildren (PAQ-S) in assessing physical activity levels: the Healthy Growth Study.
abstract: OBJECTIVE
  The aim of this paper was to evaluate the criterion validity of the Physical Activity Questionnaire for Schoolchildren (PAQ-S).
  
  
  METHODS
  The current study is a subcohort of the Healthy Growth Study, a large-scale cross-sectional study. 202 schoolchildren aged 9-13 years from Greece completed the PAQ-S and wore an accelerometer for 4 consecutive days. Time spent moderate (MPA), moderate to vigorous (MVPA) and vigorous (VPA) physical activity was calculated based on PAQ-S and accelerometer data.
  
  
  RESULTS
  The average time spent on MPA and MVPA as derived from PAQ-S and from accelerometers were significantly moderately correlated (r=0.462, P<0.001 and r=0.483, P<0.001, respectively). No significant correlation was detected between PAQ-S and accelerometer-measured time spent performing VPA (rho=0.150, P=0.057). Intraclass Correlation Coefficient (ICC) indicated a moderate agreement between PAQ-S and accelerometer in estimating MPA (ICC=0.592, P<0.001) and MVPA (ICC=0.581, P<0.001). Bland-Altman analysis revealed a small mean difference (the "bias"), between the two methods, in estimating MPA, although this difference was found to be significantly higher than zero ("bias"=27.4% of the accelerometer-measured mean score, P=0.006). On the other hand, Bland-Altman analysis revealed a large mean difference in estimating MVPA and VPA ("bias"=84.2% and 357% of the accelerometer-measured mean score for MVPA and VPA, respectively and P<0.001). The high correlation coefficient between the average and difference values between all physical activity scores derived from accelerometers and PAQ-S, indicate a systematic overestimation of physical activity time with increasing physical activity for PAQ-S.
  
  
  CONCLUSIONS
  The validity of PAQ-S for the estimation of MPA and MVPA was found to be slightly similar self-reported measures for schoolchildren. Therefore, this questionnaire could be used as a tool for physical activity assessment in large population studies.
authors.affiliation: Department of Nutrition and Dietetics, Harokopio University of Athens, Athens, Greece - manios@hua.gr.
authors.forename: Y
authors.initials: Y
authors.lastname: Manios
authors.forename: O
authors.initials: O
authors.lastname: Androutsos
authors.forename: G
authors.initials: G
authors.lastname: Moschonis
authors.forename: M
authors.initials: M
authors.lastname: Birbilis
authors.forename: K
authors.initials: K
authors.lastname: Maragkopoulou
authors.forename: A
authors.initials: A
authors.lastname: Giannopoulou
authors.forename: E
authors.initials: E
authors.lastname: Argyri
authors.forename: G
authors.initials: G
authors.lastname: Kourlaba
mesh_terms: D000293:Adolescent; D002648:Child; D003430:Cross-Sectional Studies; D005080:Exercise Test; D005260:Female; D005500:Follow-Up Studies; D006115:Greece; D006801:Humans; D008297:Male; D009043:Motor Activity / Q000502:physiology*; D012016:Reference Values; D015203:Reproducibility of Results; D012189:Retrospective Studies; D011795:Surveys and Questionnaires