Validation of using EMS dispatch codes to identify low-acuity patients.

To validate the predictive ability of previously derived emergency medical services (EMS) dispatch codes to identify patients with low-acuity illnesses. This prospective descriptive study was conducted in Rochester, New York. An expert panel reviewed and modified a previously derived set of low-priority EMS dispatch codes. Patients assigned these 21 codes between July 2002 and June 2003 were included for further analysis. Dispatch data and level of EMS care were recorded for each dispatch code. The proportion of low-acuity patients (i.e., those who received only basic life support (BLS) care or those who were not transported using lights and sirens) was determined using previously established definitions. Codes were defined as associated with low-acuity patients if the lower bound of the 95% confidence interval (CI) exceeded 90%. Medical records for patients identified as high-acuity were reviewed to evaluate whether the advanced life support (ALS) level care that was provided had a clinical impact. Emergency medical services cared for 43,602 patients during the study, and 7,540 were dispatched as low-priority. We found that 7,197 (95%; 95% CI: 95-96%) of these patients met low-acuity criteria and that 11 of the evaluated codes were validated, with low-acuity care provided at least 90% of the time. Of the 343 patients identified as high-acuity, 62 (18%; 95% CI: 14-23%) were determined to have received interventions that had a clinical impact. This study prospectively validates 11 EMS dispatch codes as being associated with low-acuity patients. These codes could be used to triage EMS patients based on dispatch information.