title: Increase in Utilization of Afterhours Medical Imaging: A Study of Three Canadian Academic Centers.
abstract: OBJECTIVE
  The objectives of our study were to assess trends in afterhours medical imaging utilization for emergency department (ED) and inpatient (IP) patient populations from 2006-2013, including analysis by modality and specialty and with adjustment for patient volume.
  
  
  METHODS
  For this retrospective study, we reviewed the number of CT, MRI, and ultrasound studies performed for the ED and IP patients during the afterhours time period (5pm - 8am on weekdays and 24 hours on weekends and statutory holidays) from 2006-2013 at three different Canadian academic hospitals. We used the Jonckheere-Terpstra (JT) test to determine statistical significance of imaging and patient volume trends. A regression model was used to examine whether there was an increasing trend over time in the volume of imaging tests per 1000 patients.
  
  
  RESULTS
  For all three sites from 2006-2013 during the afterhours time period: There was a statistically significant increasing trend in total medical imaging volume, which also held true when the volumes were assessed by modality and by specialty. There was a statistically significant increasing trend in ED and IP patient volume. When medical imaging volumes were adjusted for patient volumes, there was a statistically significant increasing trend in imaging being performed per patient.
  
  
  CONCLUSIONS
  Afterhours medical imaging volumes demonstrated a statistically significant increasing trend at all three sites from 2006-2013 when assessed by total volume, modality, and specialty. During the same time period and at all three sites, the ED and IP patient volumes also demonstrated a statistically significant increasing trend with more medical imaging, however, being performed per patient.
authors.affiliation: Department of Medical Imaging, University Health Network, Toronto General Hospital, Toronto, Ontario, Canada.
authors.forename: Shivani
authors.initials: S
authors.lastname: Chaudhry
authors.affiliation: Department of Medicine, St Michael's Hospital, Toronto, Ontario, Canada.
authors.forename: Irfan
authors.initials: I
authors.lastname: Dhalla
authors.affiliation: Applied Health Research Centre, St Michael's Hospital, Toronto, Ontario, Canada; Institute of Health Policy, Management and Evaluation, University of Toronto, Toronto, Ontario, Canada.
authors.forename: Gerald
authors.initials: G
authors.lastname: Lebovic
authors.affiliation: Department of Medical Imaging, University Health Network, Toronto General Hospital, Toronto, Ontario, Canada.
authors.forename: Patrik
authors.initials: P
authors.lastname: Rogalla
authors.affiliation: Department of Medical Imaging, St Michael's Hospital, Toronto, Ontario, Canada. Electronic address: dowdellt@smh.ca.
authors.forename: Timothy
authors.initials: T
authors.lastname: Dowdell
mesh_terms: D000046:Academic Medical Centers / Q000706:statistics & numerical data* / Q000639:trends; D000328:Adult; D039602:After-Hours Care / Q000706:statistics & numerical data* / Q000639:trends; D003952:Diagnostic Imaging / Q000706:statistics & numerical data* / Q000639:trends; D004636:Emergency Service, Hospital / Q000706:statistics & numerical data / Q000639:trends; D005544:Forecasting; D006276:Health Facility Size / Q000706:statistics & numerical data / Q000639:trends; D006301:Health Services Needs and Demand / Q000706:statistics & numerical data / Q000639:trends; D006742:Hospital Bed Capacity / Q000706:statistics & numerical data; D006801:Humans; D007902:Length of Stay / Q000706:statistics & numerical data / Q000639:trends; D008511:Medicine / Q000706:statistics & numerical data / Q000639:trends; D009864:Ontario; D014600:Utilization Review / Q000706:statistics & numerical data / Q000639:trends
keywords: Afterhours; Emergency department; Medical imaging; Radiology; Utilization trends; Volume