Purpose: To determine what types of EMS systems (public vs. private) are contributing to the peer reviewed field research in EMS and what type of research is being done by these agencies.

Methods: A Medline literature search was conducted of all peer reviewed journals using the search terms: EMS, emergency medical services, EMT, paramedic, and ambulance. Studies published between 1976 and 1995 meeting these criteria were reviewed and classified as field or non-field studies. Studies were classified as field studies if they evaluated clinical outcomes or overall EMS system structure and performance. The type of EMS system in which the study was conducted was classified as: public (PB), private (PR), or a mixture of public and private agencies (PP). If the type of system was not evident in the paper, the primary author or EMS agency was contacted by phone. The primary affiliation of the first author was classified as being with: an educational institution, hospital, government agency, or EMS agency. Each study was also classified as being primarily clinical or evaluating EMS system structure. Review articles, editorials, and meta-analyses were excluded as were studies in which critical data elements could not be verified. Fischer's exact test was used for statistical analysis.

Results: A total of 365 studies were evaluated with 66 non-field studies being excluded from analysis. 75 studies did not meet inclusionary criteria. This left 224 studies for analysis. PB systems accounted for 167 (74.5%) of field studies, with PP 44 (19.6%) and PR 13 (5.8%). Clinical studies were more commonly done by PB systems (72.5%) when compared to PR systems (38.5%), p = 0.02. System structure studies accounted for the majority of studies done by PR systems (61.5%). An affiliation with an educational institution such as a university occurred in 61.2% of the studies. The number of field studies done by PB systems has increased steadily over the last 10 years while field studies published by PR and PP systems has remained at a low level, with none published from 1992–1994.