Derivation of emergency medical services dispatch codes associated with low-acuity patients

To identify emergency medical services (EMS) dispatch codes associated with basic life support (BLS) level of prehospital care, a proxy for low illness acuity.

This retrospective cohort study was conducted in an urban city with a single advanced life support level EMS provider. The 911 center was certified in using dispatch protocols from Priority Dispatch Corporation (Salt Lake City, UT). Dispatch data on all transported EMS patients from August 2001 to April 2002 were abstracted. The authors prospectively defined a low-acuity patient as one who received BLS-level care and defined a low-acuity dispatch code as one in which at least 90% of coded patients required only BLS care. For each dispatch code or code group, the authors calculated the fraction of patients who received BLS-level care. For each "A"-level (lowest category) dispatch code group, the fraction of patients receiving BLS-level care was also evaluated.

A total of 19,332 calls met inclusion criteria and were categorized into 118 dispatch codes or code groups. Twenty-eight codes or code groups with 7,801 patients met the authors' definition of low acuity. Overall, 7,394 patients received only BLS care (94.8%, 95% confidence interval: 94.3%-95.3%). Analysis of "A"-level dispatch code groups found BLS use rates of 52.8% to 99.3%.

Certain dispatch codes are associated with the delivery of BLS-level care, indicating identification of patients likely to be low acuity. These codes are not necessarily "A"-level dispatch codes, which are commonly considered to represent the lowest-acuity patients. Future studies are needed to prospectively validate that these codes do represent low-acuity patients.