title: Value of information analysis used to determine the necessity of additional research: MR imaging in acute knee trauma as an example.
abstract: OBJECTIVE
  To help guide future outcomes research regarding the use of magnetic resonance (MR) imaging in patients with acute knee trauma in an emergency department setting, with use of prospective data from a randomized clinical trial and value of information analysis.
  
  
  METHODS
  A total of 189 patients (123 male, 66 female; mean age, 33.4 years) were randomly assigned to undergo radiography alone (n = 93) or radiography and MR imaging (n = 96). Institutional review board approval and informed consent (parental consent for minors) were obtained. During 6 months of follow-up, data on quality of life and 39 cost parameters were collected. Value-of-information analysis was used to estimate the expected benefit of future research to eliminate the decision uncertainty that remained after trial completion. In addition, the parameters that were responsible for most of the decision uncertainty were identified, the expected benefits of various study designs were evaluated, and the optimal sample size was estimated.
  
  
  RESULTS
  Only three parameters were responsible for most of the decision uncertainty: number of quality-adjusted life-years, cost of an overnight hospital stay, and friction costs. A study in which data on these three parameters are gathered would have an optimal sample size of 3500 patients per arm and would be expected to result in a societal benefit of euro 5.6 million or 70 quality-adjusted life-years.
  
  
  CONCLUSIONS
  The optimal study design for use of MR imaging to evaluate acute knee trauma involves a trial in which there are 3500 patients per trial arm, and data on the number of quality-adjusted life-years, cost of an overnight hospital stay, and friction costs are collected.
authors.affiliation: Department of Epidemiology and Biostatistics, Erasmus Medical Center, University Medical Center Rotterdam, Dr Molewaterplein 40, Room Ee 21-40a, 3015 GD Rotterdam, the Netherlands.
authors.forename: Bas
authors.initials: B
authors.lastname: Groot Koerkamp
authors.forename: Jeroen J
authors.initials: JJ
authors.lastname: Nikken
authors.forename: Edwin H
authors.initials: EH
authors.lastname: Oei
authors.forename: Theo
authors.initials: T
authors.lastname: Stijnen
authors.forename: Abida Z
authors.initials: AZ
authors.lastname: Ginai
authors.forename: M G Myriam
authors.initials: MG
authors.lastname: Hunink
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D002648:Child; D017046:Cost Savings; D003362:Cost-Benefit Analysis; D003661:Decision Support Techniques; D005260:Female; D017048:Health Care Costs / Q000706:statistics & numerical data*; D006801:Humans; D007718:Knee Injuries / Q000175:diagnosis* / Q000191:economics*; D008279:Magnetic Resonance Imaging / Q000191:economics* / Q000706:statistics & numerical data*; D008297:Male; D008875:Middle Aged; D017063:Outcome Assessment, Health Care / Q000379:methods*; D011788:Quality of Life; D006113:United Kingdom / Q000453:epidemiology