This study aimed to create a structured overview of the patient and dispatch characteristics of UPC cases, as well as to investigate the effects of sensitizing medical dispatchers to reduce the use of the UPC. The research demonstrated that the median age of patients triaged with the UPC was higher than the age of patients triaged with symptom-specific categories. Moreover, the UPC's use has been declining over the years, demonstrating a possible effect of alerting medical dispatchers about the implications of using the UPC. On top of that, EMS vehicles dispatched with the UPC were more often cancelled than EMS vehicles dispatched with the symptom-specific categories.
Sociodemographic determinants related to the use of the "unclear problem" category
The median age of patients triaged with the UPC was higher than the age of the patients triaged with the symptom-specific categories (66 vs. 58 years). In line with these results, a study based on emergency medical patients in hospitals in Denmark and California has demonstrated that non-specific diagnoses such as "other symptoms" and "other factors" constituted large groups in the elderly patient population . Although this study considered the patient population in hospitals, it correlates with the higher median age of patients triaged with the UPC.
The fact that the median age of patients triaged with the UPC is higher than the median age of patients triaged with symptom-specific categories may be explained by the elderly’s reduced capability to exchange information in a clear and precise way . Moreover, elderly patients often present with more difficult problems. Namely, a study conducted by Wachelder et al.  explained that elderly patients who visit the emergency room often have non-specific complaints due to numerous factors including comorbidities, cognitive and functional impairment and communication problems. This could similarly be an issue during the dispatching process at the EMDC. It has been shown that cardiac arrest, which frequently occurs in the elderly , is a medical condition that is difficult to spot .
EMS vehicle cancellation triaged with the UPC
The data demonstrated that 34.7% of the dispatched EMS vehicles after triage with the UPC end up being cancelled. This number is higher than the amount cancelled for non-UPC cases, which is 29.7%. This study’s scope did not allow for the determination of under and over triage.
Nonetheless, the results could indicate that, in general, over-triage might be an issue in Copenhagen, and particularly when regarding the UPC, as it might suggest that in the first instance, more or higher-level emergency vehicles are sent out than necessary. However, it could also denote the opposite – if more cars are cancelled, it might mean that cases are more often under-triaged as vehicles could be cancelled in instances where they were essential.
A study conducted in Vaud, Switzerland, evaluated over and under triage from their criteria-based dispatch system. They found that, both in cases of under and over triage, "undefined problem", was the most used criterion. This criterion represented 38% of over triage and 83.6% of under triage cases . Considering the same dispatch system was used as in the EMDC, this could indicate that the UPC indeed leads to more over and under triage.
Møller et al.  found a higher mortality rate for emergency priority level B cases categorized as UPC. Level B cases are cases that are urgent, but not life threatening. Møller et al. state that this might imply that a higher priority level should have been used in the medical dispatch process. In other words, that there was a problem of under-triaging, with a subsequent detrimental effect on patient outcomes. However, they stated that if a higher priority level is used in the medical dispatch process, this will increase EMS demand whilst there are limited EMS resources. Therefore, it could interfere with adequately responding to other patients in need of EMS services .
The impacts of sensitizing medical dispatchers about the use of the UPC to reduce its use
As can be seen from the register-based results, the use of the UPC has been steadily decreasing over the period of the study. Throughout the period of the study, medical dispatchers have been alerted about the implications of using the UPC with the attempt to reduce its use. The use of the UPC has shown the greatest decrease out of all the different categories. This could indicate that alerting medical dispatchers about the implications of the use of the UPC at the EMDC in Copenhagen had a positive effect.
Other studies have also shown positive effects after the implementation of a new protocol in EMDCs. The introduction of a new protocol in EMDCs to improve cardiac arrest identification by medical dispatchers and increase conduction of medical-dispatcher-assisted CPR to patients has shown to be effective [14, 15]. Although these studies were not related to the UPC, it further exemplifies that new protocols can have beneficial effects in the medical dispatching process, similarly to how the protocols implemented at the EMDC in Copenhagen have reduced the usage of the UPC.
This study shows that the median age of patients dispatched with the UPC is higher than that of patients dispatched with symptom-specific categories. It demonstrates that UPC incidents are more often cancelled, and therefore could have negative effects on patient outcomes or the efficient use of resources. Moreover, this study reports a reduction in the use of the UPC after educating medical dispatchers with the aim to improve the triage process and reduce the use of the UPC. This research sheds light on research opportunities and improvements with regard to UPC use.
A limitation of the study is that although observations can be drawn from the results, no causal inferences can be established, and further research is required to achieve that. Qualitative research could indicate why medical dispatchers decided to opt for the UPC, their opinion about the use and existence of this category, and this could show where improvements could be made in the EMDC. Moreover, suppose the patient outcomes could be linked to the data. In that case, it could clarify whether the triage is not excessive or rather insufficient and measures could subsequently be taken to provide a more accurate medical dispatching process.
Moreover, it is known that the dispatchers were alerted about the use of the UPC, yet there is no further information about how this process was undertaken. The decrease of the UPC could be related to educating medical dispatchers about the implications of using the UPC, yet this cannot be proven.
Additionally, the analysis does not include the medical dispatchers' factors, such as sociodemographic factors, their professional background, or mental state, which might affect emergency call categorization.
This research showed that the patient and dispatch characteristics of the UPC are different than the patient and dispatch characteristics of symptom-specific categories. To better investigate the impacts of the UPC, qualitative research and research on patient outcomes need to be done.
Moreover, if it is known how the medical dispatchers were alerted about the implications of the use of the UPC, then this could facilitate implementation of future improvements in medical dispatching, not only at the EMDC but also in other Danish regions or even internationally. Another topic that could be interesting to regard for future research is how artificial intelligence could aid medical dispatchers in choosing a correct medical dispatching category and thereby reduce their use of the unclear category. Blomberg et al. [16, 17] emphasize artificial intelligence's skill to recognize out of hospital cardiac arrest, yet acknowledge that future studies are needed to improve human–computer interaction.
Although this research has denoted some possible gaps in the system that could be improved to reduce the use of the UPC, it would be interesting to look into other tools to reduce its use. This study could lead to further research and serve as a starting point for an improved, more efficient EMDC in Copenhagen. A better EMDC could subsequently benefit Danish society. Furthermore, other EMDCs in Europe could take note of this research. This report could be a stimulus for EMDC leaders to investigate their medical dispatching categorization system and the implications that come along with it, to make further improvements.