title: Performance of the assessment of quality of life measure in people with hip and knee joint disease and implications for research and clinical use.
abstract: OBJECTIVE
  To comprehensively evaluate the performance of the Assessment of Quality of Life (AQoL) instrument for measuring health-related quality of life (HRQOL) in people with hip and knee joint disease (arthritis or osteoarthritis).
  
  
  METHODS
  Data from 237 individuals were available for analysis from a national cross-sectional, population-based study of hip and knee joint disease in Australia. AQoL-4D data were evaluated using Rasch analysis. A range of measurement properties was explored, including model and item fit, threshold ordering, differential item functioning, and targeting.
  
  
  RESULTS
  Good overall fit of the AQoL with the Rasch model was demonstrated across a range of tests, supporting internal validity. Only 1 item (relating to hearing) showed evidence of misfit. Most AQoL items showed logical sequencing of response option categories, with threshold disordering evident for only 2 of the 12 items (items 4 and 9). Minor issues with potential clinical and research implications include limited options for reporting pain and some evidence of measurement bias between demographic subgroups (including age and sex). Participants' HRQOL was generally better than that represented by the AQoL items (mean ± SD for person abilities -2.15 ± 1.39, mean ± SD for item difficulties 0.00 ± 0.67), indicating ceiling effects that could impact the instrument's ability to detect HRQOL improvement in population-based studies.
  
  
  CONCLUSIONS
  The AQoL is a competent tool for assessing HRQOL in people with hip and knee joint disease, although researchers and clinicians should consider the caveats identified when selecting appropriate HRQOL measures for future outcome assessment involving this patient group.
authors: Melbourne EpiCentre, Royal Melbourne Hospital, and The University of Melbourne, Parkville, Victoria, Australia.
authors: Ilana N
authors: IN
authors: Ackerman
authors: Lucy
authors: L
authors: Busija
authors: Mark A
authors: MA
authors: Tacey
authors: Megan A
authors: MA
authors: Bohensky
authors: Zanfina
authors: Z
authors: Ademi
authors: Caroline A
authors: CA
authors: Brand
authors: Danny
authors: D
authors: Liew
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D015233:Models, Statistical; D015207:Osteoarthritis, Hip; D020370:Osteoarthritis, Knee; D017063:Outcome Assessment, Health Care / Q000379:methods*; D011788:Quality of Life; D012219:Rheumatology / Q000379:methods*