This study shows that the patient transport rate in emergency incidents without emergency physician involvement is related to both the reason for deployment as well as the type of municipality of the deployment site. Particularly low PTQs are found for deployments related to certain fire brigade incidents and in connection with messages from personal emergency response system call centres to the dispatch centres, as well as deployments in urban areas. In addition, longer on-scene times were identified for emergency incidents without patient transport than for transport incidents.
The use of ambulance and emergency medical services has already been examined in numerous studies [1,33,34,42], and new market entrants such as passenger transport service providers like Uber can also lead to changes in the use of ambulance resources [32]. In addition, correlations of ambulance service use with socioeconomic factors have been described [12,25]. Current discussions also consider factors influencing telemedicine, including the need for transport and the need for emergency physicians at the scene [14,18,28]. Billittier, Moscati et al. already described in 1996 that, in addition to medical reasons for patients, the lack of alternative transport options also plays a role in the use of the emergency medical services [11]. Laukkanen et. al. researched that ambulance personnel are usually able to safely assess patients at the scene when there is no patient transport [29].
A study by Infinger, Studnek et al. (2013) showed that for an ambulance service with an average annual call volume of about 90,000 calls for two patients per day, the correct resource is a nurse consultation and not the dispatch of an ambulance [23]. A retrospective cohort study from Finland by Hoikka, Silfvast et al. (2017) concluded that in 13,354 ambulance calls, 41.7% of patients were not transported [22]. However, the comparability with the present study is limited, as Hoikka, Silfvast et al. also included emergency physician deployments and therefore all physician decisions not to transport are also included. In our approach, we deliberately chose to leave out this medical decision, as our primary aim was to shed light on the dispatching decision of the dispatch centre. Therefore, it is possible, that the ILS assessment is biased due to the presence of a physician at the scene of emergency. Generally this is less likely associated for deployments without an emergency physician, because medical decisions for or against transport would require a related diagnosis that can be made neither by the dispatcher nor by the ambulance service staff on the scene. Khorram-Manesh, Lennquist Montán et al. (2011) demonstrated a discrepancy between the dispatch centre assessment and the actual priority, resulting in unnecessary hospital transports [26]. In the international literature there is a review by Jensen, Carter et al. (2015) on dispatching alternatives to the classic ambulance, which includes a total of 16 studies and 44 scientific articles on this topic [24]. This paper presents a variety of evaluation methods but concludes that comparability is difficult to establish due to the heterogeneity of the systems. For the evaluation and classification of this study, the authors contacted the Fachverband Leitstellen e.V. and the Stelle zur trägerübergreifenden Qualitätssicherung im Rettungsdienst [Office for Interagency Quality Assurance in Rescue Services] Baden-Württemberg (SQR-BW) in Germany and the Leitstelle Tirol [Integrated Dispatch Centre Tyrol] in Austria with identical research questions. This showed that both within Germany and in the neighbouring Austrian state of Tyrol, comparisons of ambulance deployments without patient transport are not valid due to different legal and billing bases. Within Germany, there is a need for a common database for emergency service data (analogous to the German Resuscitation Register [19,27] or the German Trauma Register DGU® [21,45]) as a basis for future research. The MIND data set that exists to date is apparently not implemented in a uniform manner, but would contain a defined set of characteristics and characteristic descriptions authorised by the Deutsche Interdisziplinäre Vereinigung für Intensiv- und Notfallmedizin [German Interdisciplinary Association for Intensive Care and Emergency Medicine] (DIVI) that are required for the documentation of prehospital emergency rescue by rescue and emergency medical services [16,31].
In the case of a RoT, while it can essentially be a non-emergency deployment (erroneous deployment), other reasons can also be responsible for why the patient is not taken to a treatment facility. In addition, the on-scene time does not indicate when the ambulance will be available again for further deployments - the transport interval (transport and transfer to a treatment facility) must be added to the TP. However, very low on-scene times for RoT missions with the reasons "fire alarm system" (9.02 minutes on-scene time) and "personal emergency response system active alarm" (10.55 minutes on-scene time) could indicate incorrect deployments for the ambulance service.
In view of the very low PTQ for the reason "fire alarm system", it is conceivable that in the future it will be necessary to consider whether it is appropriate to dispatch an ambulance for this type of deployment when planning the alarm. "personal emergency response system active alarm" could involve cases where the personal emergency response system call centres do not have their own transport service. This circumstance could be improved by the obligatory introduction of an on-call driving service for personal emergency response system call centres, because then their own resources could take over these deployments instead of an ambulance.
Another factor influencing the PTQ is the community type for the place of deployment: in urban areas, the PTQ is lower than in rural areas, although there are more publicly accessible care services such as on-call practices or day clinics. This partial result of our study corresponds with other studies, such as the analysis of the performance level in the rescue service for the years 2016 and 2017 by the Federal Highway Research Institute ("BAST Study"). In this study, the distribution of false trips in rural regions is 2.2% and in urban regions 8.9% [39]. Possible reasons for this difference may be the different composition of the patient collective, e.g. with regard to socio-economic characteristics or the anonymity of big cities. The differences in the PTQ for the reason intoxication (per 1,000 inhabitants: 57.9% without patient transport in the large city vs. 4.9% without patient transport in the rural community) could be indicative of this. Further explanations may be differing patient compliance and better accessibility of specialised clinics in urban areas. The influence of the disposition quality cannot be derived from the available data.
Transport without indication would contradict all plans of demand-oriented control of health care as shown in the expert opinion of the German Council of Economic Experts [36]. The time difference might be explained by the documentation effort that is usually included in the on-scene time for non-transports. This does not only mean the documentation of the deployment, which may not even be necessary in the case of an incorrect deployment, but also the time spent on filling out transport refusal declarations. Furthermore, it should be questioned whether infrastructural supplements to the ambulance make sense, since some patients may not need the full human and technical resource of an ambulance. In some regions of Germany, supplements to the emergency medical services are emerging, such as the pilot project of community emergency paramedics in Oldenburg [3,41] or rescue response vehicles in Schleswig-Holstein [35] and Bavaria [4], which can be alerted additively or as a substitute. With these response resources, patients who do not require transport capacity can be treated on site. In Rhineland and Hamburg, more than half of the emergency outpatients were treated in hospital in 2018. For 55 per cent of them, only the emergency flat rate was billed - an indication that the patients might have been better off in the statutory emergency service [2,37].
Limitations
For the interpretation and presentation of results it must be taken into account that the existing reasons for deployment represent the final reasons for deployment in the deployment control system. In case a reason for deployment was changed by the dispatcher (e.g., because a triggered fire alarm system turned out to be a real fire event), the altered reason for deployment is found in the evaluation.
The data basis and the conclusions of this study are based on the data collection of integrated dispatch centres in Bavaria and Bavarian legislation. A transfer to other federal states of the Federal Republic of Germany as well as a transfer to international circumstances is not possible, since legal framework conditions and documentation differ from those in Bavaria. In the entire Free State of Bavaria, the financing of the ambulance service is carried out on the basis of the service level with a state-wide uniform billing of the user fees via the Zentrale Abrechnungsstelle für den Rettungsdienst Bayern GmbH [Central Billing Office for the Bavarian Ambulance Service GmbH] (ZAST) ) [7], which is legally entrusted with the implementation. Due to these legal framework conditions, there are no monetary incentives for the provider of the rescue service to transport a patient to a care facility. Especially if taking this into consideration, study results will differ under other framework conditions - nationally and internationally - which, however, also emphasises the relevance in a changing political environment.
A methodological limitation results from the fact that for all reasons for deployment, the dispatchers could also use the real condition descriptions and not the basic reasons for use. For example, when a dispatcher receives a message from a personal emergency response system call centre with the message image "fallen person", he or she can decide whether to select the reason for deployment as "personal emergency response system active alarm" or a "fall". For a further evaluation in future studies, the complete deployment process in the dispatch centre must therefore be considered. The present study does not give any indication as to why a patient was not transported. For this, further investigations are necessary, such as interviews with the ambulance staff or an analysis of the mission documentation. Furthermore, this study did not examine the medical reasonableness of a transport.