# Ambulance patients with altered level of consciousness: a registry-based cohort study from the North Denmark Region in 2017–2021

## TL;DR

This study examines ambulance patients with altered consciousness and finds that lower Glasgow Coma Scale scores are strongly linked to higher 30-day mortality rates.

## Contribution

The study provides a large-scale analysis of prehospital patients with altered consciousness and their outcomes in a real-world setting.

## Key findings

- One in eight ambulance patients had altered consciousness, with most having a GCS score of 14.
- Patients with a GCS score of 3 had a 60% 30-day mortality rate, while those with a score of 14 had 10%.
- Mortality odds increased significantly as GCS scores decreased, with a score drop from 14 to 9–13 doubling the odds of death.

## Abstract

An altered level of consciousness (ALOC) in emergency patients is linked to poor outcomes. Glasgow Coma Scale (GCS), initially made for head injury patients, but often used in both trauma and other patients. GCS assesses consciousness, with scores ranging from 15 (fully aware) to 3 (deep coma). Assessing GCS is quickly done and does not require technical equipment, unlike other vital signs. This study aims to characterize unselected prehospital ALOC patients brought to a hospital and assess their mortality.

Retrospective observational cohort study.

Patients transported by ambulance to a hospital in the North Denmark Region between 2017 and 2021, with a first registered GCS of 3–14, were included. The reason for calling the emergency number, subsequent ICD-10 diagnoses given at hospital, and raw and adjusted mortality, were reported.

Fifteen thousand two hundred thirty-five patients were included. One in eight ambulance patients had ALOC, most with a GCS score of 14. The primary reason for calling the emergency number was decreased consciousness or paralysis, except for those with a GCS score of 3–8, where the most common reason was unconsciousness/possible cardiac arrest. Most patients received non-specific diagnoses at hospital, which covers a wide range of symptoms and abnormal findings. Those with a GCS score of 3, most frequently were diagnosed with circulatory diseases, especially cardiac arrest and more diverse diagnostic picture among the others, including trauma, strokes, syncope, seizures and poisoning as the most frequent. Among patients with a GCS score of 3, 60% had died within 30 days, whereas 10% had died among patients with a GCS score of 14. The odds of mortality increased as GCS scores decreased, with a decrease from 14 to 9–13 more than doubled the odds of dying (OR 2.3, p < 0.001).

Among unselected prehospital emergency patients brought to a hospital, every eight had ALOC. The patient group was heterogenic concerning the reasons for calling the emergency number and diagnoses given at hospital. ALOC was associated with high 30 days mortality, including 10% for GCS of 14. ALOC, also in milder degree, is a serious sign in a broad prehospital patient population.

The online version contains supplementary material available at 10.1186/s13049-026-01562-z.