title: Validity of two physical activity questionnaires (IPAQ and PAQA) for Vietnamese adolescents in rural and urban areas.
abstract: BACKGROUND
  Although physical activity is recognised to be an important determinant of health and nutritional status, few instruments have been developed to assess physical activity in developing countries. The aim of this study was to compare the validity of the short form of the International Physical Activity Questionnaire (IPAQ) and a locally adapted version of the Physical Activity Questionnaire for Adolescents (PAQA) for use in school going adolescents in rural and urban areas in Vietnam.
  
  
  METHODS
  Sixteen year old adolescents from rural areas (n = 137) and urban areas (n = 90) completed the questionnaires in 2006. Test-retest reliability was assessed by comparing registrations after 2 weeks. Criterion validity was assessed by comparison with 7 days continuous accelerometer logging. Validity of the two methods was assessed using Spearman correlation coefficient, intra class correlation coefficients (ICC) and Kappa statistics.
  
  
  RESULTS
  Reliability of both questionnaires was poor for both the IPAQ (ICC = 0.37) and the PAQA (ICC = 0.40). Criterion validity of both questionnaires was acceptable and similar for the IPAQ (rho = 0.21) and the PAQA (rho = 0.27) but a significantly lower validity was observed in rural areas. Both forms poorly estimated time spent on light, moderate and vigorous physical activity. Agreement of both questionnaires to classify individuals was also low but the IPAQ performed better than the PAQA.
  
  
  CONCLUSIONS
  Both questionnaires have a similar and overall poor validity to be used as a population instrument in Vietnam. Low reliability and classification properties in rural areas call for further research for specific use in such settings.
authors.affiliation: Nutrition and Child Health Unit, Prince Leopold Institute of Tropical Medicine, Antwerp, Belgium.
authors.forename: Carl K
authors.initials: CK
authors.lastname: Lachat
authors.forename: Roosmarijn
authors.initials: R
authors.lastname: Verstraeten
authors.forename: Le Nguyen Bao
authors.initials: le NB
authors.lastname: Khanh
authors.forename: Maria
authors.initials: M
authors.lastname: Hagströmer
authors.forename: Nguyen Cong
authors.initials: NC
authors.lastname: Khan
authors.forename: Nguyen Do Anh
authors.initials: Ndo A
authors.lastname: Van
authors.forename: Nguyen Quang
authors.initials: NQ
authors.lastname: Dung
authors.forename: Patrick W
authors.initials: PW
authors.lastname: Kolsteren