title: Cost implications of unwarranted imaging for distant metastasis in women with early-stage breast cancer in Ontario.
abstract: BACKGROUND
  Despite the publication of multiple evidence-based guidelines recommending against routine imaging for distant metastasis in patients with early-stage (i/ii) breast cancer, such imaging is frequently performed. The present retrospective cohort study was conducted to estimate the cost of unnecessary imaging tests in women with stage i and ii breast cancer diagnosed between 1 January 2007 and 31 December 2012 in Ontario.
  
  
  METHODS
  We obtained patient-level demographic and tumour data from a large provincial dataset. The total cost of unwarranted imaging tests (in 2015 Canadian dollars) was considered to be equal to the sum of imaging costs incurred between 2007 and 2012 and was stratified by disease stage, imaging modality, and body site.
  
  
  RESULTS
  Of the 26,547 identified patients with early-stage breast cancer, 22,811 (85.9%) underwent at least 1 imaging test, with an average of 3.7 tests per patient (3.2 for stage i patients and 4.0 for stage ii patients) over 5 years. At least 1 imaging test was performed in 79.6% of stage i and 92.7% of stage ii patients. During a 5-year period, the cost of unwarranted imaging in patients with early-stage breast cancer ranged from CA$4,418,139 to CA$6,865,856, depending on guideline recommendations.
  
  
  CONCLUSIONS
  Our study highlights the substantial cost of excess imaging that could be saved and re-allocated to patient care if evidence-based guidelines are followed. Future studies should assess strategies to ensure that evidence-based guidelines are followed and to increase awareness of the cost implications of nonadherence to guidelines.
authors.affiliation: Clinical Epidemiology Program, The Ottawa Hospital Research Institute, Ottawa, ON;; School of Epidemiology, Public Health and Preventive Medicine, University of Ottawa, Ottawa, ON;; Institute for Clinical Evaluative Sciences, Toronto, ON;
authors.forename: K
authors.initials: K
authors.lastname: Thavorn
authors.affiliation: Clinical Epidemiology Program, The Ottawa Hospital Research Institute, Ottawa, ON;; Department of Statistics and Actuarial Science, University of Waterloo, Waterloo, ON;
authors.forename: Z
authors.initials: Z
authors.lastname: Wang
authors.affiliation: Clinical Epidemiology Program, The Ottawa Hospital Research Institute, Ottawa, ON;; School of Epidemiology, Public Health and Preventive Medicine, University of Ottawa, Ottawa, ON;
authors.forename: D
authors.initials: D
authors.lastname: Fergusson
authors.affiliation: Clinical Epidemiology Program, The Ottawa Hospital Research Institute, Ottawa, ON;
authors.forename: S
authors.initials: S
authors.lastname: van Katwyk
authors.affiliation: Division of Surgical Oncology, Department of Surgery, Ottawa Hospital, Ottawa, ON;; Cancer Therapeutics Program, The Ottawa Hospital Research Institute, Ottawa, ON;
authors.forename: A
authors.initials: A
authors.lastname: Arnaout
authors.affiliation: Division of Medical Oncology, Department of Medicine, The Ottawa Hospital Cancer Centre, and University of Ottawa, Ottawa, ON.
authors.forename: M
authors.initials: M
authors.lastname: Clemons
keywords: Costs; Ontario; early-stage breast cancer; unwarranted imaging for distant metastasis