Novel Methodology for Linking 9-1-1 Dispatch Categories with a Death Registry: Mortality Rates of Selected Dispatch Categories.

Objectives: Medical Priority Dispatch System (MPDS) is a system used to assign medical 9-1-1 calls to one of 35 chief complaints that are further categorized in order of increasing priority, Alpha through Echo. In this descriptive study we demonstrate the methodology of matching MPDS codes to a county mortality registry. We also evaluated the ability of select MPDS codes (fall, respiratory, sick person, and abdominal pain) to predict mortality up to 30 d for all ages transported by Alameda County Emergency Medical Services (EMS).

Methods: Using Alameda County EMS data, we conducted a retrospective review of all EMS encounters that occurred from November 1, 2011, to November 1, 2016. To describe mortality in this population, we identified unique patients and linked them to the Alameda County Public Health Death Registry. We identified mortality at 48 h, 7 d, and 30 d after an EMS encounter.

Results: Approximately 99% of the EMS encounters were matched with unique patient identifiers, yielding a study sample of 202,431 (4% less than age 18, 53% between ages 18-65, and 43% over age 65). Patients with a respiratory chief complaint had the highest mortality percentage in each age group (0.23%, 2.7%, and 14.55% respectively). There was no correlation between the MPDS code and mortality for patients less than age 18. An increase in Alpha through Echo designation for respiratory complaints in patients 18-65 and older than 65 years corresponded with an increase in 30-day mortality.

Conclusions: This study demonstrates an upward trend in mortality with increasing acuity of Alpha through Echo designations for adult patients with respiratory complaints. Mortality increased with age in this cohort. Most of the deaths occurred after 7 days.