title: Which is the most useful patient-reported outcome in femoroacetabular impingement? Test-retest reliability of six questionnaires.
abstract: OBJECTIVE
  The most reliable patient-reported outcomes (PROs) for people with femoroacetabular impingement (FAI) is unknown because there have been no direct comparisons of questionnaires. Thus, the aim was to evaluate the test-retest reliability of six existing PROs in a single cohort of young active people with hip/groin pain consistent with a clinical diagnosis of FAI.
  
  
  METHODS
  Young adults with clinical FAI completed six PRO questionnaires on two occasions, 1-2 weeks apart. The PROs were modified Harris Hip Score, Hip dysfunction and Osteoarthritis Score, Hip Outcome Score, Non-Arthritic Hip Score, International Hip Outcome Tool, Copenhagen Hip and Groin Outcome Score.
  
  
  RESULTS
  30 young adults (mean age 24 years, SD 4 years, range 18-30 years; 15 men) with stable symptoms participated. Intraclass correlation coefficient(3,1) values ranged from 0.73 to 0.93 (95% CI 0.38 to 0.98) indicating that most questionnaires reached minimal reliability benchmarks. Measurement error at the individual level was quite large for most questionnaires (minimal detectable change (MDC95) 12.4-35.6, 95% CI 8.7 to 54.0). In contrast, measurement error at the group level was quite small for most questionnaires (MDC95 2.2-7.3, 95% CI 1.6 to 11).
  
  
  CONCLUSIONS
  The majority of the questionnaires were reliable and precise enough for use at the group level. Samples of only 23-30 individuals were required to achieve acceptable measurement variation at the group level. Further direct comparisons of these questionnaires are required to assess other measurement properties such as validity, responsiveness and meaningful change in young people with FAI.
authors.affiliation: Department of Physiotherapy, Centre for Health, Exercise and Sports Medicine, School of Health Sciences, The University of Melbourne, , Melbourne, Victoria, Australia.
authors.forename: Rana S
authors.initials: RS
authors.lastname: Hinman
authors.forename: Fiona
authors.initials: F
authors.lastname: Dobson
authors.forename: Amir
authors.initials: A
authors.lastname: Takla
authors.forename: John
authors.initials: J
authors.lastname: O'Donnell
authors.forename: Kim L
authors.initials: KL
authors.lastname: Bennell
mesh_terms: D000293:Adolescent; D000328:Adult; D005260:Female; D057925:Femoracetabular Impingement / Q000175:diagnosis*; D006801:Humans; D008297:Male; D010147:Pain Measurement; D063868:Patient Outcome Assessment; D011446:Prospective Studies; D015203:Reproducibility of Results; D057566:Self Report; D011795:Surveys and Questionnaires / Q000592:standards*; D055815:Young Adult
keywords: Groin injuries; Hip disorder; Measurement; Sporting injuries