title: Computerized adaptive test for patients with knee impairments produced valid and responsive measures of function.
abstract: OBJECTIVE
  Assess practicality of using a computerized adaptive test (CAT) in routine clinical practice, perform a psychometric evaluation of content range coverage and test precision, and assess known group construct validity, sensitivity to change and responsiveness of knee CAT functional status (FS) measures.
  
  
  METHODS
  Secondary analysis of retrospective intake and discharge rehabilitation FS data collected in a prospective cohort study. Data represented a convenience sample of 21,896 patients with knee impairments receiving outpatient physical therapy in 291 clinics in 30 U.S. states (2005-2007).
  
  
  RESULTS
  The CAT used an average of seven items to produce precise estimates of FS that adequately covered the content range with negligible floor and ceiling effects. Test information functions and standard errors supported FS measure precision. FS measures discriminated patients by age, symptom acuity, surgical history, condition complexity, and prior exercise history in clinically logical ways. Seventy-two percent of patients obtained discharge FS measures > or = minimal detectable change (95% confidence interval). Change of 9 FS units (0-100 scale) represented minimal clinically important improvement, which 67% of patients obtained.
  
  
  CONCLUSIONS
  The knee CAT was efficient and produced precise, valid, and responsive measures of FS for patients receiving therapy for knee impairments and functioned well in routine clinical application.
authors.affiliation: Focus On Therapeutic Outcomes Inc, White Stone, VA, 22578-2403, USA. hart@fotoinc.com
authors.forename: Dennis L
authors.initials: DL
authors.lastname: Hart
authors.forename: Ying-Chih
authors.initials: YC
authors.lastname: Wang
authors.forename: Paul W
authors.initials: PW
authors.lastname: Stratford
authors.forename: Jerome E
authors.initials: JE
authors.lastname: Mioduski
mesh_terms: D000203:Activities of Daily Living; D000293:Adolescent; D000328:Adult; D000368:Aged; D003936:Diagnosis, Computer-Assisted / Q000379:methods*; D004812:Epidemiologic Methods; D005260:Female; D006801:Humans; D007592:Joint Diseases / Q000503:physiopathology / Q000534:rehabilitation*; D007719:Knee Joint / Q000503:physiopathology*; D008297:Male; D008875:Middle Aged; D010044:Outpatient Clinics, Hospital; D026741:Physical Therapy Modalities; D011594:Psychometrics; D016059:Range of Motion, Articular; D020127:Recovery of Function; D055815:Young Adult