title: Routine magnetic resonance imaging for idiopathic olfactory loss: a modeling-based economic evaluation.
abstract: OBJECTIVE
  Idiopathic olfactory loss is a common clinical scenario encountered by otolaryngologists. While trying to allocate limited health care resources appropriately, the decision to obtain a magnetic resonance imaging (MRI) scan to investigate for a rare intracranial abnormality can be difficult.
  
  
  OBJECTIVE
  To evaluate the cost-effectiveness of ordering routine MRI in patients with idiopathic olfactory loss.
  
  
  METHODS
  We performed a modeling-based economic evaluation with a time horizon of less than 1 year. Patients included in the analysis had idiopathic olfactory loss defined by no preceding viral illness or head trauma and negative findings of a physical examination and nasal endoscopy.
  
  
  METHODS
  Routine MRI vs no-imaging strategies.
  
  
  METHODS
  We developed a decision tree economic model from the societal perspective. Effectiveness, probability, and cost data were obtained from the published literature. Litigation rates and costs related to a missed diagnosis were obtained from the Physicians Insurers Association of America. A univariate threshold analysis and multivariate probabilistic sensitivity analysis were performed to quantify the degree of certainty in the economic conclusion of the reference case. The comparative groups included those who underwent routine MRI of the brain with contrast alone and those who underwent no brain imaging. The primary outcome was the cost per correct diagnosis of idiopathic olfactory loss.
  
  
  RESULTS
  The mean (SD) cost for the MRI strategy totaled $2400.00 ($1717.54) and was effective 100% of the time, whereas the mean (SD) cost for the no-imaging strategy totaled $86.61 ($107.40) and was effective 98% of the time. The incremental cost-effectiveness ratio for the MRI strategy compared with the no-imaging strategy was $115 669.50, which is higher than most acceptable willingness-to-pay thresholds. The threshold analysis demonstrated that when the probability of having a treatable intracranial disease process reached 7.9%, the incremental cost-effectiveness ratio for MRI vs no imaging was $24 654.38. The probabilistic sensitivity analysis demonstrated that the no-imaging strategy was the cost-effective decision with 81% certainty at a willingness-to-pay threshold of $50 000.
  
  
  CONCLUSIONS
  This economic evaluation suggests that the most cost-effective decision is to not obtain a routine MRI scan of the brain in patients with idiopathic olfactory loss. Outcomes from this study may be used to counsel patients and aid in the decision-making process.
authors.affiliation: Division of Otolaryngology-Head and Neck Surgery, Department of Surgery, University of Calgary, Calgary, Alberta, Canada.
authors.forename: Luke
authors.initials: L
authors.lastname: Rudmik
authors.affiliation: Division of Otolaryngology-Head and Neck Surgery, Department of Surgery, University of Calgary, Calgary, Alberta, Canada.
authors.forename: Kristine A
authors.initials: KA
authors.lastname: Smith
authors.affiliation: Division of Rhinology and Sinus Surgery, Department of Otolaryngology-Head and Neck Surgery, Medical University of South Carolina, Charleston.
authors.forename: Zachary M
authors.initials: ZM
authors.lastname: Soler
authors.affiliation: Division of Rhinology and Sinus Surgery, Department of Otolaryngology-Head and Neck Surgery, Medical University of South Carolina, Charleston.
authors.forename: Rodney J
authors.initials: RJ
authors.lastname: Schlosser
authors.affiliation: Oregon Sinus Center, Division of Rhinology and Sinus Surgery, Department of Otolaryngology-Head and Neck Surgery, Oregon Health and Science University, Portland.
authors.forename: Timothy L
authors.initials: TL
authors.lastname: Smith
mesh_terms: D003287:Contrast Media; D003362:Cost-Benefit Analysis; D003663:Decision Trees; D004724:Endoscopy; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000191:economics*; D018803:Models, Economic; D000857:Olfaction Disorders / Q000175:diagnosis*; D010808:Physical Examination
chemical_list: D003287:Contrast Media