Computed tomography scan utilization in emergency departments: A multi-state analysis

Background: Increased utilization of computed tomography (CT) in emergency departments (EDs) has become a concern due to its expense and the potential risks associated with radiation exposure. Objective: To describe the predictors of CT utilization based on patient, provider, and ED characteristics. Methods: There were 3,217,396 ED patient visits during a 12-month period that were included in this retrospective analysis of a database from a single billing company that included 227 EDs in 41 states. Data were collected between January 1, 2006 and December 31, 2006 and included patient visit information, CT use for each patient visit, patient demographics, ED provider information, and ED volume. Results: The CT utilization rate was 16.7% (95% confidence interval [CI] 16.716.8%) for adults, whereas in pediatric patients (< 18 years of age) it was 5.3% (95% CI 5.35.4%). The adult CT utilization rate ranged from 11.3% (95% CI 11.211.4%) at age 2029 years to 24.6% (95% CI 24.524.8%) for those > 65 years of age. For the admitted patients, the CT utilization rate was 27.8% (95% CI 27.627.9%); for the patients transferred out of the hospital, the CT utilization rate was 23.2% (95% CI 22.923.6%). Discharged patients had a rate of 11.3% (95% CI 11.211.3%) and patients who left against medical advice had a scan rate of 20.2% (95% CI 19.620.7%). The CT utilization rate was 9.3% (95% CI 9.29.4%) in EDs with < 20,000 annual visits and increased to 17.8% (95% CI 17.717.9%) in EDs with volumes of > 40,000. The CT utilization rate was 16.1% (95% CI 16.116.2%) for emergency medicine boarded physicians vs. 11.3% (95% CI 11.311.4%) for non-emergency-medicine boarded physicians. Conclusions: CT utilization by EDs seems to vary by a number of parameters, including patient age, ED volume, training background of the provider, and disposition status of the patient.