Characteristics of severely injured trauma patients transported by helicopter emergency medical services in Switzerland: a retrospective cohort study.

Background: Information on severely injured patients transported by helicopter emergency medical services (HEMS) in Switzerland is scarce. This study, with a special focus on sex differences, aimed to gain insights into the demographics, injury characteristics and outcomes of these patients and to provide data that could help improve prehospital trauma care.

Methods: This is a retrospective multicentre cohort study analysing data collected by the Swiss Trauma Registry. Patients aged 16 or older, who were admitted by helicopter emergency medical services to a level 1 trauma centre in Switzerland between 2018 and 2022, with an Injury Severity Score (ISS) of ≥16, were included.

Results: Overall, 2714 trauma patients were analysed in the present study. The majority of these patients were male (73.7%). Blunt trauma was the main cause of injury (93.6%), with traffic accidents (43.5%) and falls (43.3%) being the most common accident mechanisms. A greater percentage of male patients than female patients were involved in motorcycle crashes (16.5% vs 6.9%, p <0.001). Female patients were more frequently involved in accidents as pedestrians (6% vs 2.7%, p <0.001) and experienced more falls below 3 metres of height (22.9% vs 14.7%, p <0.001). The median ISS of our cohort was 24 (interquartile range [IQR]: 19-30). The most common injuries were thoracic trauma (67%), head trauma (66.7%) and spine trauma (50.3%). Men suffered more thoracic injuries (68.9% vs 61.9%, p = 0.001) and their median Abbreviated Injury Score (AIS) Thorax was significantly higher (3.0 [IQR: 0-3] vs 2.0 [IQR: 0-3], p <0.001). Women had a higher prevalence of pelvic fractures (29.3% vs 21.5%, p <0.001) and suffered more fractures of long bones in their upper extremities (22.2% vs 15.7%, p <0.001). There was no significant difference in in-hospital mortality between women and men (15.7% vs 14.6%, p = 0.493), nor in other outcome parameters.

Conclusion: To our knowledge, this is the first analysis of data on severely injured trauma patients transported by helicopter emergency medical services in Switzerland. While there were notable differences between women and men in terms of accident mechanisms and injury characteristics, no significant differences in outcome parameters were observed.