title: Prediction of poor outcomes six months following total knee arthroplasty in patients awaiting surgery.
abstract: BACKGROUND
  Identification of patients experiencing poor outcomes following total knee arthroplasty (TKA) before the intervention could allow better case selection, patient preparation and, likely, improved outcomes. The objective was to develop a preliminary prediction rule (PR) to identify patients enrolled on surgical wait lists who are at the greatest risk of poor outcomes 6 months after TKA.
  
  
  METHODS
  141 patients scheduled for TKA were recruited prospectively from the wait lists of 3 hospitals in Quebec City, Canada. Knee pain, stiffness and function were measured 6 months after TKA with the Western Ontario and McMaster Osteoarthritis Index (WOMAC) and participants in the lowest quintile for the WOMAC total score were considered to have a poor outcome. Several variables measured at enrolment on the wait lists (baseline) were considered potential predictors: demographic, socioeconomic, psychosocial, and clinical factors including pain, stiffness and functional status measured with the WOMAC. The prediction rule was built with recursive partitioning.
  
  
  RESULTS
  The best prediction was provided by 5 items of the baseline WOMAC. The rule had a sensitivity of 82.1% (95% CI: 66.7-95.8), a specificity of 71.7% (95% CI: 62.8-79.8), a positive predictive value of 41.8% (95% CI: 29.7-55.0), a negative predictive value of 94.2% (95% CI: 87.1-97.5) and positive and negative likelihood ratios of 2.9 (95% CI: 1.8-4.7) and 0.3 (95% CI: 0.1-0.6) respectively.
  
  
  CONCLUSIONS
  The developed PR is a promising tool to identify patients at risk of worse outcomes 6 months after TKA as it could help improve the management of these patients. Further validation of this rule is however warranted before clinical use.
authors.forename: Eugen
authors.initials: E
authors.lastname: Lungu
authors.affiliation: Orthopaedic Clinical Research Unit, Maisonneuve-Rosemont Hospital University of Montreal affiliated Research Center, CP 6128 Succursale Centre-Ville, Montréal H3C 3 J7 Quebec, Canada. f.desmeules@umontreal.ca.
authors.forename: François
authors.initials: F
authors.lastname: Desmeules
authors.forename: Clermont E
authors.initials: CE
authors.lastname: Dionne
authors.forename: Etienne L
authors.initials: EL
authors.lastname: Belzile
authors.forename: Pascal-André
authors.initials: PA
authors.lastname: Vendittoli
mesh_terms: D000368:Aged; D019645:Arthroplasty, Replacement, Knee / Q000639:trends*; D015331:Cohort Studies; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008137:Longitudinal Studies; D008297:Male; D008875:Middle Aged; D020370:Osteoarthritis, Knee / Q000175:diagnosis / Q000453:epidemiology* / Q000601:surgery*; D011237:Predictive Value of Tests; D011446:Prospective Studies; D013997:Time Factors; D016896:Treatment Outcome; D014850:Waiting Lists