title: Osteoporosis Assessment Questionnaire-Physical Function (OPAQ-PF): a psychometrically validated osteoporosis-targeted patient reported outcome measure of daily activities of physical function.
abstract: The purpose of this study was to evaluate the measurement properties of the Osteoporosis Assessment Questionnaire-Physical Functioning (OPAQ-PF). Based on this study, the OPAQ-PF has confirmed unidimensionality and acceptable reliability, construct validity, and sensitivity to change in a recent fracture/no recent fracture osteoporosis sample.
  
  
  METHODS
  Dimensionality was established through exploratory and confirmatory factor analysis. Patients completed three patient reported outcome (PRO) measures and four performance-based measures (PBMs) at baseline to enable an evaluation of construct validity. Patients without a recent fracture completed the OPAQ-PF 2 weeks after baseline to enable an evaluation of test-retest reliability. Ability to detect change and interpretation of change were investigated following completion of the OPAQ-PF 12 and 24 weeks postbaseline by patients with a recent fracture.
  
  
  RESULTS
  A prospective psychometric validation study in 144 postmenopausal women, with moderate to severe osteoporosis, 37 of whom had experienced a recent fragility fracture (<6 weeks). Unidimensionality was established for the OPAQ-PF by factor analysis. The OPAQ-PF had good internal consistency (α = 0.974) and test-retest reliability (mean intraclass correlation coefficient (ICC) 0.993. The OPAQ-PF differentiated between patients with/without recent fracture, and by severity of osteoarthritis; it correlated strongly with hypothesized-related scales and PBMs (r > 0.3, p < 0.001). Ability to detect change was established with high correlations between changes in OPAQ-PF score and changes in global concept scores in recent fracture patients (r ≥ 0.6, 24-week change). Effect size of change on OPAQ-PF score increased by level of global change (p < 0.001). Anchor-based methods identified an OPAQ-PF change of 10 at an individual patient level and 20 at a group level as meaningful to patients.
  
  
  CONCLUSIONS
  The OPAQ-PF has confirmed unidimensionality and acceptable reliability, construct validity, and sensitivity to change in a recent fracture/no recent fracture osteoporosis sample.
authors.affiliation: Oxford Outcomes, an ICON Plc. Company, Oxford, UK.
authors.forename: A
authors.initials: A
authors.lastname: Nixon
authors.forename: C
authors.initials: C
authors.lastname: Kerr
authors.forename: H
authors.initials: H
authors.lastname: Doll
authors.forename: A N
authors.initials: AN
authors.lastname: Naegeli
authors.forename: S L
authors.initials: SL
authors.lastname: Shingler
authors.forename: K
authors.initials: K
authors.lastname: Breheny
authors.forename: R
authors.initials: R
authors.lastname: Burge
authors.forename: D T
authors.initials: DT
authors.lastname: Gold
authors.forename: S
authors.initials: S
authors.lastname: Silverman
mesh_terms: D000203:Activities of Daily Living; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D005260:Female; D006801:Humans; D008875:Middle Aged; D009043:Motor Activity; D015663:Osteoporosis, Postmenopausal / Q000503:physiopathology / Q000534:rehabilitation*; D058866:Osteoporotic Fractures / Q000503:physiopathology / Q000534:rehabilitation; D063868:Patient Outcome Assessment; D011379:Prognosis; D011446:Prospective Studies; D011594:Psychometrics; D015203:Reproducibility of Results; D012720:Severity of Illness Index; D012959:Socioeconomic Factors; D011795:Surveys and Questionnaires; D014481:United States
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