Can Emergency Medical Dispatch Codes Predict Prehospital Interventions for Common 9-1-1 Call Types?

Abstract

Objective. The Medical Priority Dispatch System is an emergency medical dispatch (EMD) system that is widely used to categorize 9-1-1 calls andoptimize resource allocation. This study evaluates the ability of EMD andnon-EMD codes (calls not processed by EMD) to predict prehospital use of medications andprocedures. Methods. All transported prehospital patients placed in an EMD or non-EMD category that exceeded 500 total calls from January 1, 2004, to December 31, 2006, in a suburban California county were matched with their prehospital electronic patient care record. These records (N = 69,541) were queried for the following prehospital interventions: basic life support (BLS) care only, intravenous line placement only, medication given, andprocedures. Advanced life support (ALS) interventions were defined as the administration of a medications or a procedure. The numbers of medications andprocedures that were performed on patients in each EMD code were measured. Results. Thirty-one of 141 EMD andnon-EMD codes met inclusion criteria andcomprised 73% of all calls during the study period. Non-EMD codes accounted for 48% of all calls in this study. Patients with shortness of breath, chest pain, diabetic problems, andaltered mental status received the most medications. High rates of medication administration were also seen in the following codes: 17A (fall, 27%), 17B (fall, 14%), EMDX (unable to complete EMD process, 22%), MED (medical aid requested—details to follow, 26%), andMED3 (medical aid requested by police—code 3, 18%). Procedures were performed on only 0.9% of all calls, of which 75% were related to advanced airways. Higher rates of ALS interventions in higher-acuity categories (Alpha, Bravo, etc.) were seen in a number of EMD categories, including seizure, laceration/hemorrhage, sick, andtraffic accident, but not seen in many categories, including abdominal pain, falls, andchest pain. Conclusions. This study demonstrated only a modest ability of the EMD system to predict which patients would require ALS intervention. There were limited differences noted in the ALS rates between the different codes (Alpha, Bravo, etc.) in the same complaint category, bringing into question the utility of the multiple subgroups. Non-EMD codes made up a large portion of calls (48%) andshould be included in future studies.