Cross sectional study of patients deceased after calling for an ambulance in the North Denmark Region with review of their prehospital medical records to assess the patients’ vital status at ambulance arrival.

Denmark has a population of 5.9 million, of which approximately 10% live in the North Denmark Region [21]. The Danish healthcare system is tax-financed and free to all residents [22]. Residents are assigned a unique civil registration number, which holds information about age and sex and is a personal identifier in national registries and medical records.

The Danish emergency medical service is regionally organized and consists of several dispatch options, including lay-bystander first responders, paramedics, and physicians (anesthesiologists) [23].

The prehospital medical record contains information on initial emergency call, dispatch information, civil registration number, observations, automatically transferred vital signs from a monitor/defibrillator, drugs, treatment, cardiac arrest, and note fields [23].

In Denmark, the declaration of death requires a physician unless the person is found with lay-bystander signs of death (extensive decay or obviously fatal injuries incompatible with continued life), or the death was assessed as imminent by a physician directly involved in the care of the patient in the time before death. [8] Bystanders must, to the best of their abilities, help distressed individuals, whereas health care professionals, including paramedics, are obliged to initiate or continue cardiopulmonary resuscitation (CPR) until a physician takes over or terminates the treatment. A physician issues a death certificate when at least one of the late signs of death, stiffness of death (rigor mortis), postmortem lividity (livores mortis), and putrefaction (cadaverositas), are present. This can, depending on the situation, be performed on the scene or at the emergency department. The dead body may be left on the scene or taken to a local hospital or morgue until burial or cremation [8, 24]. After death, the citizens are registered as dead in the Danish Civil Registration System [25].

We included patients deceased on the same or following day after calling the national emergency number, 112, requesting an ambulance in the North Denmark Region in the period January 2019 to December 2021. Only patients with a valid Civil Registration Number, and who were registered as dead in the Danish Civil Registration System, were included.

The prehospital medical record was the primary data source. The Danish Civil Registration System provided information on date of death [26]. To secure inclusion of all deaths within the first 24 h after the emergency call, we included patients dead on the same or the following date as receiving an ambulance because the registry does not contain the exact time, only the date of death. This means that the included patients all deceased within a maximum of 48 h after the emergency call, either in the prehospital phase or after, at either hospital or at home. The datasets were linked using the patients’ unique civil registration numbers.

The medical review was an iterative process where the authors through discussions developed exhaustive and mutually exclusive categories of vital status at ambulance arrival and during the prehospital phase. The two first-authors defined the initial set of criteria for categorizing the patients’ vital status by performing a complete evaluation of a random sample of 100 prehospital medical records. The evaluation included the reason for calling an emergency, dispatch information, vital signs, drugs administered, treatment given, cardiac arrest section (where applicable), and note fields for the entire prehospital medical record. This was discussed by the entire author group and refined and redesigned until the final exhaustive and mutually exclusive categories were reached: 1) Dead on Ambulance Arrival (DOAA), 2) Out-of-Hospital Cardiac Arrest (OHCA), 3) Alive on Ambulance Arrival, and 4) No clear category. Table 1 describes these final categories and definitions in details, applicable for others to use. After the process of developing the categories, the two first authors assessed inter-rater reliability in a new random sample of 100 prehospital medical records. Finally, they reviewed all prehospital medical records individually and in case the patient’s vital status was unclear, discussed with senior authors.

Patients were further classified as declared dead by a physician on the scene, or presumed dead by a paramedic after conferring with a physician who gave permission not to initiate CPR, or to terminate ongoing CPR in case of OHCA (Fig. 1).

Vital status categories and outcomes. Overview of the categorization and subcategories of vital status. CPR, cardiopulmonary resuscitation

Patient data were entered and managed using REDCap electronic data capture tools hosted at the North Denmark Region. [28, 29] The “No clear category” was calculated but excluded from the analyses.

We presented descriptive statistics as proportion, median and interquartile range (IQR), and for comparative analyses we used Pearson Chi-square and Mann–Whitney U test. We stratified on year of the study period. Cohen’s Kappa was used to measure inter-rater reliability between the two authors, estimated with a 95% confidence interval.

Comparisons with a p-value < 0.05 were considered statistically significant.

Statistical analyses were conducted in StataCorp. 2021. Stata Statistical Software: Release 17. College Station, TX: StataCorp LLC with the plugin “kappaetc” (Daniel Klein, Universität Kassel).