PT - JOURNAL ARTICLE AU - C MacFarlane AU - C A Benn TI - Evaluation of emergency medical services systems: a classification to assist in determination of indicators AID - 10.1136/emj.20.2.188 DP - 2003 Mar 01 TA - Emergency Medicine Journal PG - 188--191 VI - 20 IP - 2 4099 - http://emj.bmj.com/content/20/2/188.short 4100 - http://emj.bmj.com/content/20/2/188.full SO - Emerg Med J2003 Mar 01; 20 AB - Emergency medical services (EMS) systems, and prehospital care are difficult to evaluate. Accordingly, the true efficacy and value of such systems are difficult to determine. The multitude of variations and combinations of involved factors makes standardisation and comparison difficult, and universal indicators are hard to develop. Various attempts have been made to determine valid indicators of effectiveness, but there has been little success. Prehospital care has been seen by some as a single entity. As a result, experience from well resourced first world trauma centres has been taken, by many, to be applicable to all prehospital situations. This article attempts to assist in the development of valid EMS indicators of performance and effectiveness by categorising prehospital scenarios into a classification reflecting the reality of their conditions of practice.