Same-day deaths occurring among 112 callers who were not assessed by the EMCC to have a life-threatening condition could represent very serious undertriage. The present independent expert review of telephone call recordings and patient charts found that none of these same-day deaths were definitively preventable with high certainty—i.e. in no case was there a high probability that the death could have been avoided if the EMCC had made a different assessment. Our review identified a number of potentially preventable deaths that could possibly have been averted if the EMCC had made a different call assessment; however, these constituted a very small proportion of all non-high-acuity patients (one potentially preventable death for every 5,249 non-high-acuity 112 caller). The majority of cases in which death was deemed potentially preventable involved incorrect use or no use of dispatch protocol. Most of the potentially preventable deaths occurred with an EMS response interval of around 13 minutes or less. These were not extremely long intervals, but they would likely have been markedly shorter if the calls had been assessed as emergency level A and “blue lights and sirens” had been used. Four of the potentially preventable deaths showed EMS response intervals of 17 minutes and up to 38 minutes, which constitute time-spans that may have substantially influenced patient prognosis.

One earlier study investigated preventability of death occurring in close relation to a 112 call [5]. Among deaths occurring in lower-priority groups in Finland, Kuisma et al. reported that 1.3% were preventable, 32.9% were potentially avoidable, and 65.8% were non-preventable. These proportions of preventable and potentially preventable deaths are markedly higher compared to our present findings; however, it is unclear whether the review process and definitions of preventability were the same as in our study. The previously published chart review was a secondary aim of a Finnish study, and thus the audit process was not described in detail. A number of other audit studies have investigated early mortality related to emergency departments and trauma centres. Lu et al. performed a chart review of deaths occurring within 24 hours after admission to an in-house ward from the emergency department (ED) [2]. They found that 25.8% of early deaths were preventable. In an audit with external patient chart review, Nafsi et al. evaluated deaths that occurred within 7 days of admission to an ED, and found that 3.15% were definitely preventable and 9.46% were either possibly or probably preventable [1]. In a Dutch trauma centre audit, Saltzherr et al. reported that 2% of deaths were preventable and 27% were potentially preventable [3]. Compared to these previous studies, our present results were fairly good, with zero definitively preventable deaths and 11.8% potentially preventable deaths. This comparison must take into account the longer duration of patient contact in an ED admission compared to the short prehospital time interval. A higher proportion of deaths are likely to occur due to suboptimal treatment during the hours or days of a hospital admission than as a consequence of actions during the shorter time from a 112 call until the arrival of an ambulance and/or doctor to the patient.

For investigating whether deaths or other adverse events are avoidable, a well-planned chart review by an expert panel is a reliable method that also provides opportunity for identifying possible areas of future improvement [1],[2],[13],[14],[18]. One limitation of the present study was the incomplete registration of civil registration numbers and Danish Index codes into the EMCC software. We examined the rate of missing data in smaller clusters (e.g. comparing between the three EMCCs and between shorter time periods), which revealed no indications of selection bias. Another limitation of the study was the exclusion of some patients whose pre- and in-hospital charts were missing or insufficient, which could introduce selection bias. Since the data registration in this newly implemented EMD system is incomplete, it is not possible to guaranty that all deaths are accounted for in this study. However, the authors had no reason to believe that the group of excluded patients contained a higher proportion of preventable deaths than the included patients since all data at the EMCCs were prospectively registered. Therefore the EMCCs had no knowledge about the later death of the patients at the time the data should be registered.

The non-emergency general practitioner services and ambulance dispatches arising from this system were not included in the study. This was the case mainly because these services do not use the Danish Index for Emergency Care, which was the focus of our study. Furthermore these services are organized in different ways around the country making the availability and quality of data heterogenic.

The inclusion of only deaths occurring on the same date may constitute a limitation, since it does not include e.g. 112 calls put at 11:00 pm concerning patients who subsequently dies at e.g. 01:00 am on the following date. The inclusion of only same date deaths was mainly due to the way deaths are registered in the civil registration system, where only data on the date and not time of day is registered.

In daily clinical practice at the EMCC, it is a general impression that 112 calls that end with a suboptimal outcome for the patient or a complaint from the caller are often the result of the dispatcher failing to comply with the dispatch protocol. This impression was confirmed by the present study, as 13 of the 18 potentially preventable deaths were associated with non-compliance with the dispatch protocol. In a study of the Norwegian criteria-based dispatch protocol, Ellensen et al. reported large variations between the EMCCs regarding adherence to the dispatch protocol [19]. On average, the Norwegian dispatch protocol was followed by call-takers in 75% of calls. In a Norwegian study of EMCC handling of calls concerning intoxication, Lorem et al. reported that 89% of dispatchers used the CBD protocol, but that 33% of the calls included in the study showed deviations from the protocol [20].

Our present findings that none of the same-day deaths among non-high-acuity 112 callers were considered preventable and that few were potentially preventable, are encouraging results regarding the new EMD system in Denmark—especially when considering the young age of the system, and the almost 200,000 calls that this study was based on. A limited number of patients among the potentially preventable deaths may have suffered serious consequences of the EMCC triage. There is room for improvement in terms of systematic protocol adherence.