Description of the 2012 NEMSIS Public-Release Research Dataset

BACKGROUND: The National Emergency Medical Services Information System (NEMSIS) is a federally funded project designed to standardize emergency medical services (EMS) patient care reporting and facilitate state and national data repositories for the assessment of EMS systems of care. The purpose of this assessment is to characterize the annual NEMSIS 2012 Public-Release Research Dataset, detailing the strengths and limitations associated with use of these data for EMS quality assurance and/or research purposes. METHODOLOGY: Using descriptive statistics, we evaluated the dataset completeness (i.e., presence of missing/null values) and dataset content. To assess data generalizability, we compared age distributions to the 2010 National Hospital Ambulatory Medical Care Survey (NHAMCS). Subanalyses were conducted for cardiac arrest- and trauma-related EMS activations to describe their characteristics, treatments, and dispositions. The analysis focuses primarily on 9-1-1 EMS activations resulting in the treatment and transport of a patient, excepting the analysis conducted for out-of-hospital cardiac arrests (OHCA), which includes scene deaths. RESULTS: In 2012, 19,831,189 EMS activations were reported to NEMSIS by 8,439 agencies located in 42 states and territories. Of the 10,733,925 9-1-1 EMS activations reportedly treating and transporting a patient, the majority were attended by a paid EMT-paramedic (82%) employed by a fire-based EMS agency (25%) working in an urban area (53%). 9-1-1 call centers most likely dispatched EMS for a "sick person" (14%), while providers most likely reported pain (26%) as the patient's primary symptom and "traumatic injury" (13%) as the likely cause. NEMSIS data adequately characterize specific patient populations and demonstrate significant similarity to independent distributions of EMS patients (i.e., NHAMCS), yet missing data and use of null values remain prevalent. CONCLUSIONS: The annual NEMSIS Public-Release Research Dataset is a valuable resource for evaluating the U.S. EMS activation population and can be used to conduct in-depth descriptions of the care of specific populations. However, the utility of the data are limited until the number of null values can be diminished and reporting becomes universal.