• Lawrence H Brown, Michael W Hubble, David C Cone, Michael G Millin, Brian Schwartz, P Daniel Patterson, Brad Greenberg, and Michael E Richards.
• Department of Emergency Medicine, University of New Mexico Health Sciences Center, Albuquerque, New Mexico, USA. lawrence.brown@jcu.edu.au
• Prehosp Emerg Care. 2009 Oct 1;13(4):516-27.

IntroductionReducing unnecessary ambulance transports may have operational and economic benefits for emergency medical services (EMS) agencies and receiving emergency departments. However, no consensus exists on the ability of paramedics to accurately and safely identify patients who do not require ambulance transport. Objective. This systematic review and meta-analysis evaluated studies reporting U.S. paramedics' ability to determine medical necessity of ambulance transport.MethodsPubMed, Cumulative Index to Nursing and Allied Health Literature (CINAHL), and Cochrane Library databases were searched using Cochrane Prehospital and Emergency Care Field search terms combined with the Medical Subject Headings (MeSH) terms "triage"; "utilization review"; "health services misuse"; "severity of illness index," and "trauma severity indices." Two reviewers independently evaluated each title to identify relevant studies; each abstract then underwent independent review to identify studies requiring full appraisal. Inclusion criteria were original research; emergency responses; determinations of medical necessity by U.S. paramedics; and a reference standard comparison. The primary outcome measure of interest was the negative predictive value (NPV) of paramedic determinations. For studies reporting sufficient data, agreement between paramedic and reference standard determinations was measured using kappa; sensitivity, specificity, and positive predictive value (PPV) were also calculated.ResultsFrom 9,752 identified titles, 214 abstracts were evaluated, with 61 studies selected for full review. Five studies met the inclusion criteria (interrater reliability, kappa = 0.75). Reference standards included physician opinion (n = 3), hospital admission (n = 1), and a composite of physician opinion and patient clinical circumstances (n = 1). The NPV ranged from 0.610 to 0.997. Results lacked homogeneity across studies; meta-analysis using a random-effects model produced an aggregate NPV of 0.912 (95% confidence interval: 0.707-0.978). Only two studies reported complete 2 x 2 data: kappa was 0.105 and 0.427; sensitivity was 0.992 and 0.841; specificity was 0.356 and 0.581; and PPV was 0.158 and 0.823.ConclusionThe results of the few studies evaluating U.S. paramedic determinations of medical necessity for ambulance transport vary considerably, and only two studies report complete data. The aggregate NPV of the paramedic determinations is 0.91, with a lower confidence limit of 0.71. These data do not support the practice of paramedics' determining whether patients require ambulance transport. These findings have implications for EMS systems, emergency departments, and third-party payers.

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