title: The Impact of Clinical Decision Rules on Computed Tomography Use and Yield for Pulmonary Embolism: A Systematic Review and Meta-analysis.
abstract: Validation studies have confirmed the accuracy of clinical decision rules for the evaluation of pretest probability of pulmonary embolism. It has been assumed that clinical decision rules will also decrease testing in actual practice, but the evidence for this is unclear. We perform a systematic review of impact analyses on clinical decision rules for pulmonary embolism.
  
  
  
  MEDLINE, EMBASE, and the Cochrane Library were searched without language restriction for studies assessing the effect of clinical decision rules on efficiency (computed tomography [CT] angiography use and yield) and safety (missed pulmonary embolism) through October 2014. Two reviewers independently extracted data on study characteristics, methods, risk of bias, and outcomes.
  
  
  
  Eight studies (n=6,677) contained sufficient information, including 1 randomized trial and 7 observational studies. Because of heterogeneity, the results of 4 studies of moderate to high quality assessing the Wells criteria were pooled. The pooled CT angiography yield was 9% (95% confidence interval [CI] 6% to 12%) in the control group and 12% (95% CI 11% to 14%) in the intervention group, for a 3% increase in yield (95% CI 1% to 5%), relative risk 1.3 (95% CI 1.1 to 1.6). We were unable to report a pooled estimate of CT angiography use. Of 2 studies with sufficient information, there was no difference in the rate of missed pulmonary embolism between intervention and control groups. No studies used a cluster-randomized design.
  
  
  
  Among participants with suspected pulmonary embolism, implementation of the Wells criteria was associated with a modest increase in CT angiography yield. There is a lack of cluster-randomized trials to confirm the efficacy of clinical decision rules for the diagnosis of pulmonary embolism.
authors.affiliation: Department of Emergency Medicine, University of California, San Francisco, San Francisco, CA. Electronic address: ralph.wang@ucsf.edu.
authors.forename: Ralph C
authors.initials: RC
authors.lastname: Wang
authors.affiliation: Department of Medicine, University of California, San Francisco, San Francisco, CA.
authors.forename: Stephen
authors.initials: S
authors.lastname: Bent
authors.affiliation: Department of Emergency Medicine, University of California, San Francisco, San Francisco, CA.
authors.forename: Ellen
authors.initials: E
authors.lastname: Weber
authors.affiliation: Department of Emergency Medicine, University of California, San Francisco, San Francisco, CA.
authors.forename: Jersey
authors.initials: J
authors.lastname: Neilson
authors.affiliation: Department of Radiology and Biomedical Imaging and Department of Epidemiology and Biostatistics, University of California, San Francisco, CA.
authors.forename: Rebecca
authors.initials: R
authors.lastname: Smith-Bindman
authors.affiliation: Department of Emergency Medicine, University of California, San Francisco, San Francisco, CA.
authors.forename: Jahan
authors.initials: J
authors.lastname: Fahimi
mesh_terms: D000072226:Computed Tomography Angiography / Q000706:statistics & numerical data*; D019091:Critical Pathways; D003661:Decision Support Techniques; D004636:Emergency Service, Hospital; D006801:Humans; D011655:Pulmonary Embolism / Q000000981:diagnostic imaging*; D014481:United States