title: Unmet needs and waiting list prioritization for knee arthroplasty.
abstract: BACKGROUND
  There is a high volume of unmet needs for knee arthroplasty in the population despite the increase in surgery rates. Given the long waiting times to have a knee arthroplasty, some governments have proposed prioritization systems for patients on waiting lists based on their level of need.
  
  
  OBJECTIVE
  We therefore estimated the needs and demand of knee arthroplasty in four regions of Spain during a 5-year period.
  
  
  METHODS
  We developed a discrete event simulation model to reproduce the process of knee arthroplasty. The prioritization system was compared with the usual waiting list management strategy (by waiting time only).
  
  
  RESULTS
  Under the prioritization system, patients saved an average of 4.5 months (95% confidence interval, 4.4-4.6 months) adjusted by level of need. The proportion of patients who experienced excessive waiting times was small and was associated with low levels of priority. The 5-year projection of the volume of unmet needs for knee arthroplasty remained stable; however, although the volume of need for the first knee arthroplasty decreased by 12%, the volume of need for an arthroplasty in the contralateral knee increased by 50%.
  
  
  CONCLUSIONS
  The data suggested the prioritization system was more beneficial than assigning surgery by waiting time only. The 5-year projection of the volume of unmet needs for knee arthroplasty remained stable, despite the increase in the need for contralateral knee arthroplasty.
  
  
  METHODS
  Level II, economic and decision analyses. See Guidelines for Authors for a complete description of levels of evidence.
authors.affiliation: Evaluation and Clinical Epidemiology Department, Hospital del Mar-IMIM, Passeig Marítim, 25-29, Barcelona 08003, Spain.
authors.forename: Mercè
authors.initials: M
authors.lastname: Comas
authors.forename: Rubén
authors.initials: R
authors.lastname: Román
authors.forename: José Maria
authors.initials: JM
authors.lastname: Quintana
authors.forename: Xavier
authors.initials: X
authors.lastname: Castells
mesh_terms: D019645:Arthroplasty, Replacement, Knee / Q000706:statistics & numerical data*; D002391:Catchment Area, Health / Q000706:statistics & numerical data; D003198:Computer Simulation; D005260:Female; D006292:Health Priorities / Q000706:statistics & numerical data*; D006301:Health Services Needs and Demand / Q000706:statistics & numerical data*; D006801:Humans; D008297:Male; D008875:Middle Aged; D017146:Models, Organizational; D018579:Patient Selection; D013030:Spain; D014850:Waiting Lists