title: Validity of instruments to measure physical activity may be questionable due to a lack of conceptual frameworks: a systematic review.
abstract: BACKGROUND
  Guidance documents for the development and validation of patient-reported outcomes (PROs) advise the use of conceptual frameworks, which outline the structure of the concept that a PRO aims to measure. It is unknown whether currently available PROs are based on conceptual frameworks. This study, which was limited to a specific case, had the following aims: (i) to identify conceptual frameworks of physical activity in chronic respiratory patients or similar populations (chronic heart disease patients or the elderly) and (ii) to assess whether the development and validation of PROs to measure physical activity in these populations were based on a conceptual framework of physical activity.
  
  
  METHODS
  Two systematic reviews were conducted through searches of the Medline, Embase, PsycINFO, and Cinahl databases prior to January 2010.
  
  
  RESULTS
  In the first review, only 2 out of 581 references pertaining to physical activity in the defined populations provided a conceptual framework of physical activity in COPD patients. In the second review, out of 103 studies developing PROs to measure physical activity or related constructs, none were based on a conceptual framework of physical activity.
  
  
  CONCLUSIONS
  These findings raise concerns about how the large body of evidence from studies that use physical activity PRO instruments should be evaluated by health care providers, guideline developers, and regulatory agencies.
authors.affiliation: Centre for Research in Environmental Epidemiology, Barcelona, Spain.
authors.forename: Elena
authors.initials: E
authors.lastname: Gimeno-Santos
authors.forename: Anja
authors.initials: A
authors.lastname: Frei
authors.forename: Fabienne
authors.initials: F
authors.lastname: Dobbels
authors.forename: Katja
authors.initials: K
authors.lastname: Rüdell
authors.forename: Milo A
authors.initials: MA
authors.lastname: Puhan
authors.forename: Judith
authors.initials: J
authors.lastname: Garcia-Aymerich
mesh_terms: D000203:Activities of Daily Living; D002908:Chronic Disease; D006331:Heart Diseases / Q000503:physiopathology*; D006801:Humans; D009043:Motor Activity; D017063:Outcome Assessment, Health Care / Q000379:methods*; D011594:Psychometrics; D029424:Pulmonary Disease, Chronic Obstructive / Q000503:physiopathology*; D011795:Surveys and Questionnaires