In this retrospective population-based cohort study, the associations between hospital admission and mortality among non-conveyed patients following high-acuity dispatches were assessed. An overall non-conveyance rate of 14% was identified, and the main finding was that less than one in four non-conveyed patients was admitted to a hospital within 48 h following their initial contact with the EMS. The 30-day mortality rate in non-conveyed patients was 2%, including patients who had previously been declared as having a terminal illness.

Different EMS systems have divergent approaches to non-conveyance. Further, variations in regional legislation on non-conveyance and education among EMS personnel and inconsistencies in study designs challenge the comparison of findings. The non-conveyance rate within the present study is comparable to what has previously been reported based on global data on the general population [2]. The fact that this study only included high-acuity dispatches should, of course, be considered when interpreting these results. The Danish EMS is mostly staffed by physicians and paramedics, but in Region Zealand, the personnel in the vehicles are solely paramedics and emergency technicians, which makes the comparison more feasible with other countries’ EMS.

The findings of this study indicate notable distinctions between non-conveyed and conveyed patients across various facets. Non-conveyance generally involved younger patients within this study, which is aligned with reported findings from previous studies [4, 20]. This observation suggests an association between increasing age and the need for medical interventions or examinations at the hospital. Previous studies support the equitable distribution of sex between non-conveyed and conveyed patients [2, 4, 20]. Notably, when considering the non-conveyed population, male sex was associated with a 42% increase in the risk of mortality. Further, male sex was associated with a 17% increased risk of admission. On-scene-time was significantly longer for non-conveyed patients; this finding aligns with previous research and may be explained by the fact that non-conveyance decisions are often multifaceted and time-consuming [21, 22]. Data regarding these associations within non-conveyed patients remain scarce, and focus on confounding is limited; thus, further research is required prior to interpretation in a meaningful context.

From a patient safety standpoint, it holds significance that most non-conveyed patients exhibited an absence of subsequent admissions and mortality, consistent with prior research findings [6, 11, 23]. Among non-conveyed patients, the crude mortality rate was 2%. Despite variations in conditions, dispatch priory level and time intervals of outcomes, the mortality rate observed in this study aligns with comparable studies, wherein reported mortality rates have ranged from 0 to 2.3% [6, 11, 12, 23]. Yet, the adjusted risk of mortality within non-conveyed patients was significantly higher compared to conveyed patients. This could be explained by the unknown proportion of patients declared terminally ill within the non-conveyed cohort [12]. Nonetheless, this finding stresses the need for additional research to ascertain possible confounders and risk factors associated with this correlation. Finally, a high-acuity dispatch would be sent to patients with suspected cardiac arrest, according to the Danish Index [16]. If the patient is legally deceased, there may be a risk of misclassification regarding registering non-conveyance.

In the context of the patient-centred approach, it is imperative to consider both patient satisfaction and patient autonomy. Non-conveyance decision-making may be influenced by patients’ preferences; however, it is noteworthy that the body of research within this domain remains scarce [24].

Data on the LOS within the initially non-conveyed population are limited. This study found that most patients from both cohorts had relatively short lengths of stay, as visualised in Fig. 4. For future research, the divergence regarding the LOS in admitted initially non-conveyed patients is relevant, in line with the economic implications inherent in these findings.

The most frequent chief complaint was “chest pain”, followed by “impaired consciousness” and “unclear problems”, with the latter accounting for 11.6% of all patients. Previous studies have demonstrated that patients presenting with unclear or unspecific complaints are older [25]. Further, it has been shown that a significant proportion of those presenting with unspecific complaints sustained underlying severe conditions associated with increased morbidity and mortality [26]. When considering the discharge diagnoses of this study, the most prevalent diagnosis was symptoms, signs and abnormal clinical and laboratory findings, not elsewhere classified. This study found that approximately 50% of patients with unclear complaints were given an unspecific discharge diagnosis. This is consistent with previous findings by Ibsen et al. [27]. There has been increased focus on stratification of patients presenting with chest pain since studies have shown that a majority of these patients suffer from low-risk conditions [28, 29]. An interesting pattern was revealed concerning patients presenting with chest pain since only 20% resulted in a diagnosis of cardiovascular disease, whereas 60% resulted in unspecific diagnoses (Fig. 3). These findings underscore the challenges within this field and expose the need for further research.

A strength of this study was the large sample size and population-based study design. Further, the comprehensiveness of the employed registries ensured thorough follow-up, mitigating the potential for selection bias. Additionally, equitable availability of prehospital health care services ensures that the process of inclusion remains unaffected by variations in socioeconomic status. The latter may pose implications for the decision of non-conveyance, and future research could benefit from adjusting for this potential confounder. While the data for this study were comprehensive, the fact that the reason for non-conveyance was not available is a limitation. Further, Region Zealand EMS operates with trained paramedics and physician support available for conferences prior to non-conveyance decisions, which may limit generalizability to regions with different EMS competencies available. Caution is advised when extrapolating findings beyond Denmark, highlighting the need for further research. Further, the non-randomized design represents an inherent susceptibility to selection bias, potentially influencing the extent to which the findings can be extrapolated. In this present study, it was not possible to clarify the causes behind non-conveyed decisions; in addition to this, there was no information regarding patients’ perspectives on non-conveyance. Within the group of initially non-conveyed patients, 11% were admitted within 3 h of the non-conveyance decision. Unfortunately, it was beyond the scope of the present study to evaluate this subgroup. However, it could have been relevant to investigate the means of transport in this group. Additionally, this study only investigated high-acuity dispatches, which challenge the generalisability to the general population.