title: Strategies incorporating spiral CT for the diagnosis of acute pulmonary embolism: a cost-effectiveness analysis.
abstract: OBJECTIVE
  To assess the cost-effectiveness of spiral CT for the diagnosis of acute pulmonary embolism.
  
  
  METHODS
  Computer-based cost-effectiveness analysis.
  
  
  METHODS
  Simulated cohort of 1,000 patients with suspected acute pulmonary embolism (PE), with a prevalence of 28.4%, as in the Prospective Investigation of Pulmonary Embolism Diagnosis study.
  
  
  METHODS
  Using a decision-analysis model, seven diagnostic strategies were compared, which incorporated combinations of ventilation-perfusion (V/Q) scans, duplex ultrasound of the legs, spiral CT, and conventional pulmonary angiography.
  
  
  RESULTS
  Expected survival and cost (in Canadian dollars) at 3 months were estimated. Four of the strategies yielded poorer survival at higher cost. The three remaining strategies were as follows: (1) V/Q +/- leg ultrasound +/- spiral CT, with an expected survival of 953.4 per 1,000 patients and a cost of $1,391 per patient; (2) V/Q +/- leg ultrasound +/- pulmonary angiography (the "traditional" algorithm), with an expected survival of 953.7 per 1,000 patients and a cost of $1,416 per patient; and (3) spiral CT +/- leg ultrasound, with an expected survival of 958.2 per 1,000 patients and a cost of $1,751 per patient. The traditional algorithm was then excluded by extended dominance. The cost per additional life saved was $70,833 for spiral CT +/- leg ultrasound relative to V/Q +/- leg ultrasound +/- spiral CT.
  
  
  CONCLUSIONS
  Spiral CT can replace pulmonary angiography in patients with nondiagnostic V/Q scan and negative leg ultrasound findings. This approach is likely as effective as-and possibly less expensive than-the current algorithm for diagnosis of acute PE. When spiral CT is the initial diagnostic test, followed by leg ultrasound, expected survival improves but costs are also considerably higher. These findings were robust to variations in the assumed sensitivity and specificity of spiral CT.
authors.affiliation: Division of Cardiology, McGill University Health Centre, McGill University, Montreal, Quebec, Canada.
authors.forename: D I
authors.initials: DI
authors.lastname: Paterson
authors.forename: K
authors.initials: K
authors.lastname: Schwartzman
mesh_terms: D000208:Acute Disease; D000465:Algorithms; D000792:Angiography / Q000191:economics; D003362:Cost-Benefit Analysis; D003661:Decision Support Techniques; D006801:Humans; D007866:Leg / Q000000981:diagnostic imaging; D008432:Mathematical Computing; D011651:Pulmonary Artery / Q000000981:diagnostic imaging; D011655:Pulmonary Embolism / Q000175:diagnosis*; D012680:Sensitivity and Specificity; D014057:Tomography, X-Ray Computed / Q000191:economics* / Q000401:mortality; D014463:Ultrasonography