title: Utilization of cardiac computed tomography angiography and outpatient invasive coronary angiography in Ontario, Canada.
abstract: BACKGROUND
  Cardiac computed tomography angiography (coronary CTA) has emerged as a non-invasive method of diagnosing coronary artery disease. The extent of utilization and uptake of this technology since initiation of its funding by the government of Ontario is unknown.
  
  
  OBJECTIVE
  The aim of our study was to examine coronary CTA utilization and the rates of elective invasive coronary angiography and revascularization before and after funding initiation.
  
  
  METHODS
  We studied all coronary CTAs performed on adults in Ontario after initiation of funding. We also used an interrupted time series analysis to compare the average monthly rates of invasive angiography and revascularization before and after initiation of funding.
  
  
  RESULTS
  There was an initial steep increase in age-and sex-standardized rates of coronary CTA from 5.0 to 11.4/100,000 over the first two quarters after funding initiation. Afterwards, there was a gradual increase in utilization from 11.4 to 17.1/100,000 over two subsequent calendar years. There was a significant reduction in both the mean monthly outpatient invasive coronary angiography (from 20.7 to 19.9 per 100,000 (p = 0.0004)) and revascularization (from 4.9 to 4.4 per 100,000 (p < 0.0001)) rates in the three years following introduction of the coronary CTA billing code as compared to the three prior to its introduction.
  
  
  CONCLUSIONS
  Since the introduction of coronary CTA funding in Ontario, there has been a steady and controlled increase in its utilization. The increasing use of coronary CTA was associated with a reduction in both the rates of invasive angiography and revascularization.
authors.affiliation: Institute for Clinical Evaluative Sciences (ICES), Canada; Schulich Heart Program and the Sunnybrook Research Institute, Sunnybrook Health Sciences Centre, Canada; Institute for Health Policy, Management and Evaluation (IHPME), Canada.
authors.forename: Idan
authors.initials: I
authors.lastname: Roifman
authors.affiliation: Institute for Clinical Evaluative Sciences (ICES), Canada.
authors.forename: Mohammad R
authors.initials: MR
authors.lastname: Rezai
authors.affiliation: Institute for Clinical Evaluative Sciences (ICES), Canada; Schulich Heart Program and the Sunnybrook Research Institute, Sunnybrook Health Sciences Centre, Canada; Institute for Health Policy, Management and Evaluation (IHPME), Canada.
authors.forename: Harindra C
authors.initials: HC
authors.lastname: Wijeysundera
authors.affiliation: University of Ottawa Heart Institute, University of Ottawa, Ottawa, Ontario, Canada.
authors.forename: Benjamin J W
authors.initials: BJ
authors.lastname: Chow
authors.affiliation: Schulich Heart Program and the Sunnybrook Research Institute, Sunnybrook Health Sciences Centre, Canada; Department of Medical Biophysics, University of Toronto, Toronto, Ontario, Canada.
authors.forename: Graham A
authors.initials: GA
authors.lastname: Wright
authors.affiliation: Institute for Clinical Evaluative Sciences (ICES), Canada; Schulich Heart Program and the Sunnybrook Research Institute, Sunnybrook Health Sciences Centre, Canada; Institute for Health Policy, Management and Evaluation (IHPME), Canada. Electronic address: tu@ices.on.ca.
authors.forename: Jack V
authors.initials: JV
authors.lastname: Tu
mesh_terms: D000368:Aged; D000553:Ambulatory Care / Q000191:economics / Q000706:statistics & numerical data*; D016507:Cardiology Service, Hospital / Q000191:economics / Q000706:statistics & numerical data*; D017023:Coronary Angiography / Q000191:economics / Q000379:methods / Q000706:statistics & numerical data*; D003324:Coronary Artery Disease / Q000000981:diagnostic imaging* / Q000191:economics; D003331:Coronary Vessels / Q000000981:diagnostic imaging*; D003430:Cross-Sectional Studies; D016208:Databases, Factual; D005260:Female; D017721:Hospital Costs; D006801:Humans; D008297:Male; D008875:Middle Aged; D009864:Ontario; D011237:Predictive Value of Tests; D013997:Time Factors; D014057:Tomography, X-Ray Computed / Q000191:economics / Q000706:statistics & numerical data*
keywords: Cardiac computed tomography angiography; Health policy; Invasive coronary angiography; Resource utilization