Diagnosis and mortality of emergency department patients in the North Denmark region.

Background: Emergency departments handle a large proportion of acute patients. In 2007, it was recommended centralizing the Danish healthcare system and establishing emergency departments as the main common entrance for emergency patients. Since this reorganization, few studies describing the emergency patient population in this new setting have been carried out and none describing diagnoses and mortality. Hence, we aimed to investigate diagnoses and 1- and 30-day mortality of patients in the emergency departments in the North Denmark Region during 2014-2016.

Methods: Population-based historic cohort study in the North Denmark Region (580,000 inhabitants) of patients with contact to emergency departments during 2014-2016. The study included patients who were referred by general practitioners (daytime and out-of-hours), by emergency medical services or who were self-referred. Primary diagnoses (ICD-10) were retrieved from the regional Patient Administrative System. For non-specific diagnoses (ICD-10 chapter 'Symptoms and signs' and 'Other factors'), we searched the same hospital stay for a specific diagnosis and used this, if one was given. We performed descriptive analysis reporting distribution and frequency of diagnoses. Moreover, 1- and 30-day mortality rate estimates were performed using the Kaplan-Meier estimator.

Results: We included 290,590 patient contacts corresponding to 166 ED visits per 1000 inhabitants per year. The three most frequent ICD-10 chapters used were 'Injuries and poisoning' (38.3% n = 111,274), 'Symptoms and signs' (16.1% n = 46,852) and 'Other factors' (14.52% n = 42,195). Mortality at day 30 (95% confidence intervals) for these chapters were 0.86% (0.81-0.92), 3.95% (3.78-4.13) and 2.84% (2.69-3.00), respectively. The highest 30-day mortality were within chapters 'Neoplasms' (14.22% (12.07-16.72)), 'Endocrine diseases' (8.95% (8.21-9.75)) and 'Respiratory diseases' (8.44% (8.02-8.88)).

Conclusions: Patients in contact with the emergency department receive a wide range of diagnoses within all chapters of ICD-10, and one third of the diagnoses given are non-specific. Within the non-specific chapters, we found a 30-day mortality, surpassing several of the more organ specific ICD-10 chapters.

Trial Registration: Observational study - no trial registration was performed.