Over and undertriage in simulation exercises Introduction The first healthcare personnel arriving at the scene of an accident or major incident is often an ambulance crew. It is therefore of importance that they are familiar with, and can practice triage during situations were there is a lack of resources. Overtriage, when a casualty is given a priority higher than motivated, may lead to inadequate use of resources, while undertriage can be seen as a risk for medical errors. There is a consensus that up to 50% overtriage is accepted in order to have an undertriage, which is less than 5%. The aim of this study was to increase knowledge regarding prehospital personnel's triage during standardized simulation exercises.

76 standardized simulation exercises where the triage of casualties was evaluated. The exercises were part of a training program for medical command and control at scene. The students trained were all professional ambulance crew. The scenario was a fire at a football stand with 50 causalities. All in all 3800 (76 x 50) triages were performed. The simulation system used was Emergo Train System. Prior to the exercises an expert group had triaged the causalities according to the MIMMS system (sieve). Of the 50 patients 15 were triaged as T1 by the expert group and the rest were not.

Of the 3800 triages 37% (n = 410) were classified as undertriage and 13% (n = 134) as overtriage. The most frequently undertriage casualties had an airway and/or breathing problem that were not observed. The most frequently overtriage casualties had a burn injury involving 30% of body surface area or unconscious casualties.

Triage in this simulation setting did not meet acceptable standards. More triage training for ambulance crew may improve outcome. More studies are needed regarding simulation exercises as a tool for evaluating results of triage.