Epidemiology and outcomes of trauma patients transported by helicopter emergency medical services: a descriptive-analytical study

Abstract

Objective

he present study was designed and carried out to investigate the epidemiology and estimate the consequences of trauma in trauma victims transported by helicopter emergency medical services (HEMS).

Methods

The present study was a descriptive-analytical, cross-sectional census study conducted on all trauma patients (n = 25) transported by helicopter to the emergency department of Ayatollah Taleghani Hospital in Kermanshah province in 2022. Data on demographics, trauma mechanism, injury anatomical site, and outcomes were extracted from the hospital’s trauma registry. Trauma severity was evaluated using the Injury Severity Score (ISS) and Revised Trauma Score (RTS). Categorical associations were analyzed using Chi-square and Fisher’s exact tests in SPSS version 26, with significance set at P < 0.05.

Results

A total of 25 trauma patients were examined (75% male, 25% female; 8% with underlying medical conditions). The mean (± SD) scene-to-hospital transfer time was 75.25 ± 22.52 min, and the mean length of stay was 15.5 ± 2.41 days. The most common trauma mechanisms were road traffic accidents (50%) and falls > 3 m (25%). Severe/very severe trauma was present in 25% of patients, and multiple injuries (polytrauma) accounted for 25% of transfers. The overall mortality rate was 8% (n = 2). Statistically significant associations were identified between female gender and higher trauma severity (P < 0.05), female gender and head/polytrauma anatomical sites (P < 0.05), and severe/very severe trauma and overall mortality (P < 0.05). No significant association was found between transfer time or dispatch type and outcome (P > 0.05).

Conclusion

In this single-center observational study, the majority of HEMS-transported trauma patients were male, with road traffic accidents and falls (> 3 m) being the predominant mechanisms, and polytrauma the main presentation for air transfer. Due to the small sample size and descriptive nature of these findings, large-scale, multicenter prospective cohort studies are needed to evaluate the true impact of HEMS on clinical outcomes and to inform national pre-hospital protocol optimization.

Clinical trial number

Not applicable.

Introduction

Trauma is considered one of the most important global public health challenges [1]. With advances in science and technology and the industrialization of societies in recent decades, trauma and its complications have become a major problem, such that today it is the most common cause of death and disability among individuals aged 1 to 40 years [2]. Trauma refers to any blow, injury, shock, damage, or accident inflicted on the human body, provided that it originates from an external source and is not caused by an internal factor or disease within the body [3]. According to Schwartz’s textbook, trauma is defined as the transfer of energy from the environment to the human body [4]. Furthermore, trauma is the leading cause of loss of productive life years in human populations because it predominantly affects younger individuals, depriving society of its economic and social workforce, unlike other common causes of mortality such as cardiovascular diseases and cancers, which primarily affect older populations [5, 6].

Accidents are the leading cause of death in trauma cases, and road traffic incidents are the most dangerous among them [7]. Mortality from road traffic accidents (RTAs) is increasing worldwide [8]. Approximately 35% of deaths caused by accidents occur in developing countries [9]. Meanwhile, fatalities resulting from accidents account for a significant proportion of global mortality [10]. Given the high rate of accidents in Iran and the associated costs, it is possible to reduce their occurrence and the resulting damage [11]. Improving road safety and ensuring the rapid transfer of the injured can help prevent subsequent complications [12].

For assessing trauma severity in research, triage, and quality improvement, quantitative anatomical and physiological scoring tools such as the RTS and ISS are essential to evaluate the extent of injury accurately [13]. Accurate evaluation during pre-hospital interventions and transport influences treatment priorities and secondary prevention [14].

Nowadays, air ambulance services, specifically HEMS are widely utilized to expand geographical access to specialized care and shorten pre-hospital transfer times [15]. Recent global and regional literature post-2020 has increasingly focused on evaluating HEMS dispatch strategies, pre-hospital time intervals, and clinical outcomes [16, 17]. Studies by Lapidus et al. in Sweden, Griggs et al., and Blok et al. (2024) have evaluated the survival benefits and pre-hospital time dynamics associated with HEMS attendance in major trauma systems [18–20]. Similarly, research by Hu et al. highlighted the importance of standardized International Classification of Diseases (ICD) classification for HEMS transports, while Al-Thani et al. in Qatar and Stassen et al. in South Africa evaluated how geographical location and system mechanics influence in-hospital trauma outcomes and survival [1, 13]. Regionally, Azadeh et al. utilized propensity-score matching to evaluate air versus ground transfers in road traffic accidents, and Ghaffarzad et al. assessed HEMS patient outcomes in East Azerbaijan Province [2, 3].

Despite these contributions, findings regarding the precise impact of HEMS on survival and patient outcomes remain mixed across different emergency healthcare configurations, varying terrain, and distinct patient sub-populations [21]. A significant research gap persists regarding HEMS trauma epidemiology and outcomes in mountainous and topographically challenging regions of western Iran [21]. In Kermanshah Province, where rugged topography and high rates of road traffic collisions and high-altitude falls necessitate rapid aerial evacuation, detailed data on transfer metrics, injury severity patterns, and determinants of mortality remain scarce.

To address this gap, this study provides a novel census evaluation of HEMS trauma victims transported to the primary tertiary trauma center in Kermanshah Province in 2022. The objective of this study was to evaluate the epidemiological characteristics, pre-hospital transfer intervals, anatomical injury locations, and trauma severity scores (ISS and RTS) among HEMS-transported patients, and to identify their association with overall mortality and hospitalization outcomes. We hypothesized that higher trauma severity scores and specific anatomical injury sites (such as polytrauma and head trauma) are significantly associated with mortality outcomes in patients evacuated by HEMS.

Materials and methods

Study design and setting

The present study was a descriptive-analytical, cross-sectional census study conducted on trauma victims transported by HEMS to the emergency department of Ayatollah Taleghani Hospital, the main tertiary trauma center in Kermanshah Province during the year 2022. The study protocol was approved by the Ethics Committee of Kermanshah University of Medical Sciences and was reported in compliance with the STROCSS criteria [22].

Participant selection and eligibility

Because all HEMS trauma patients transferred to the hospital in 2022 were targeted, the study was conducted as a full census, eliminating the need for a sample size calculation or sampling strategy.

Inclusion Criteria: All trauma patients transported by HEMS to the emergency department of Taleghani Hospital throughout 2022 (n = 25).

Exclusion Criteria: Patients with incomplete or illegible medical record data in the trauma registry.

Data collection procedures

Data were extracted from the institutional trauma registry implemented at Taleghani Hospital using a structured checklist. The checklist captured:

Demographic Data: Gender and presence of underlying medical conditions.

Pre-Hospital and Transport Characteristics: HEMS dispatch type (direct primary scene response vs. secondary inter-hospital transfer), geographic location of incident (e.g., Kermanshah City), and time interval from the accident scene to emergency department arrival.

Trauma Characteristics: Trauma mechanism (road traffic accidents, falls > 3 m, etc.) and primary anatomical site of injury (Head, Face, Abdomen, Extremity, External, or Polytrauma/multiple injuries).

Hospital Outcomes: Length of hospital stay (days) and overall survival/mortality outcome.

Trauma severity assessment

Trauma severity was evaluated using both anatomical and physiological scoring tools:

Anatomical Evaluation ISS: Anatomical injury severity was evaluated across five body regions (Head, Face, External, Abdomen, and Extremity). Each region received a score from 1 to 5 based on the degree of anatomical impairment. To calculate the ISS, the scores of the three most severely injured body regions were squared and summed (ISS = A² + B² + C²).

Physiological Evaluation & RTS: Physiological status was measured using the RTS, which integrates physiological measurements including systolic blood pressure (SBP) and the Glasgow Coma Scale (GCS) score obtained upon evaluation.

Statistical analysis

All collected data were entered into SPSS software (version 26) for statistical analysis. Qualitative variables were summarized using frequencies and percentages (n,%), while quantitative continuous variables, such as transfer time and length of stay, were expressed as mean± standard deviation (Mean ± SD). To evaluate continuous variables, the Kolmogorov–Smirnov test was first applied to assess the normality of data distribution; normally distributed data were analyzed using parametric tests (independent samples t-test or one-way ANOVA), whereas non-normally distributed data were evaluated using non-parametric alternatives (Mann–Whitney U or Kruskal–Wallis tests). Bivariate relationships between categorical variables including gender, trauma severity, anatomical site, dispatch type, trauma mechanism, and mortality outcome were evaluated using the Chi-square test. Due to the small sample size (n = 25), Fisher’s exact test was applied whenever expected cell frequencies were less than 5, and a two-tailed P < 0.05 was considered statistically significant for all analyses.

Results

Descriptive analyses

A total of 25 trauma patients transported by helicopter to the emergency department were included in the study. Of these, 75% (n = 19) were male and 25% (n = 6) were female. Underlying medical conditions were present in 8% (n = 2) of patients.

Regarding transfer characteristics, 80% (n = 20) of patients were transported directly from the accident scene (primary dispatch), while 20% (n = 5) were secondary inter-hospital transfers. The highest frequency of trauma incidents occurred in Kermanshah County (40%, n = 10) and Salas-e Babajani, one of the counties of Kermanshah Province, Iran) (35%, n = 9).

The time interval from the accident scene to emergency department arrival varied: 54% (n = 13 or 14) arrived within 45–105 min, while 46% had transfer times either shorter than 45 min or longer than 105 min. The overall mean (± SD) scene-to-hospital transfer time was 75.25 ± 22.52 min.

The predominant mechanisms of trauma were road traffic accidents (50%, n = 13 or 12) and falls from a height exceeding 3 m (25%, n = 6 or 7). Trauma severity was classified as severe or very severe in 25% (n = 6 or 7) of cases. Regarding anatomical sites of injury, multiple injuries (polytrauma) accounted for 25% (n = 6 or 7) of transfers.

Clinical outcomes demonstrated an overall mortality rate of 8% (n = 2). The deceased patients comprised one male and one female patient:

Male Patient: Cause of death was documented as a right hip fracture, massive intra-abdominal and pelvic fluid, epidural hemorrhage, head trauma, a GCS score of approximately 3, and cardiopulmonary arrest.

Female Patient: Cause of death was documented as blunt abdominal trauma, massive free fluid, extensive right hemothorax and pneumothorax, severe blood loss, and treatment-resistant hypotension. The overall mean length of hospital stay was 15.5 ± 2.41days (Table 1).

Table 1.

Associations between trauma characteristics and gender in the studied trauma patients

Variables	Male N(%)	Female N(%)	P-value
Mechanism of trauma			0.166
Accident	4 (36.4%)	2 (14.3%)
Contact with sharp object	0 (0.0%)	1 (7.1%)
Fall	7 (63.6%)	6 (42.9%)
Crushed limb	0 (0.0%)	4 (28.6%)
Shotgun	0 (0.0%)	1 (7.1%)
Severity of trauma			0.294
Average	4 (36.4%)	0 (0.0%)
Severe	7 (63.6%)	12 (85.7%)
Very Severe	0 (0.0%)*	2 (14.3%)
Trauma outcome			0.500
Hospitalization in ward	9 (81.8%)	13 (92.9%)
Admission to intensive care	1 (9.1%)	0 (0.0%)
Death	1 (9.1%)	1 (7.1%)
Total	11 (100%)	14 (100%)

Analytical analyses

Bivariate associations between trauma characteristics, demographics, severity scores, and outcomes were evaluated using Chi-square and Fisher’s exact tests:

Demographics vs. trauma characteristics

Trauma Mechanism: No statistically significant difference was observed between male and female patients (P > 0.05).

Trauma Severity: Trauma severity differed significantly by gender (P < 0.05), with severe and very severe cases occurring more frequently in female patients.

Anatomical Site: The anatomical site of injury was significantly associated with gender (P < 0.05), with head injuries and multiple trauma occurring more frequently in female patients.

Mechanism vs. severity and anatomical site

Mechanism vs. Severity: Falls > 3 m were significantly identified as the primary mechanism leading to severe trauma (P < 0.05).

Mechanism vs. Site: Road traffic accidents were predominantly associated with head injuries (P < 0.05), whereas multiple traumas (polytrauma) were most commonly caused by falls > 3 m (P < 0.05).

Trauma severity vs. anatomical site

Trauma severity showed a statistically significant association with the anatomical site of injury (P < 0.05), with higher severity scores observed in cases presenting with head injuries and multiple traumas.

Determinants of patient outcomes (Mortality)

Anatomical Site: Trauma outcome was significantly associated with the anatomical site of injury (P < 0.05), with all deceased patients (n = 2) presenting with either multiple traumas or head injuries.

Trauma Severity: Trauma outcome was significantly associated with trauma severity (P < 0.05), with all deceased patients presenting with severe or very severe trauma scores.

Transfer Characteristics: Neither the scene-to-hospital time interval (P > 0.05) nor the type of HEMS dispatch (direct primary scene response vs. secondary inter-hospital transfer) (P > 0.05) demonstrated a statistically significant association with overall trauma outcome (Table 2).

Table 2.

Relationships between trauma variables, severity, anatomical location, mechanism, outcome, time, and transfer mode in trauma patients

Variables	Category	Hospitalization in the Ward N(%)	Admission to the Intensive Care Unit N(%)	Death N(%)	P-value
Mechanism of Trauma	Accident	4(18.2%)	1(100%)	1(50%)	0.795
	Contact with a sharp or cutting object	1(4.5%)	0(0%)	0(0%)
	Fall	12(54.5%)	0(0%)	1(50%)
	Crushed limb following impact with a heavy object	4(18.2%)	0(0%)	0(0%)
	Shotgun	1(4.5%)	0(0%)	0(0%)
	Total	22(100%)	1(100%)	2(100%)
Anatomical Location of Trauma	Multiple trauma	18(81.8%)	1(100%)	1(50%)	0.031
	Head injury	1(4.5%)	0(0%)	1(50%)
	Damage to other organs	3(13.6%)	0(0%)	0(0%)
	Total	22(100%)	1(100%)	2(100%)
Severity of Trauma	Average	3(13.6%)	0(0%)	0(0%)	0.031
	Severe	18(81.8%)	1(100%)	1(50%)
	Very severe	1(4.5%)	0(0%)	1(50%)
	Total	22(100%)	1(100%)	2(100%)
Time distance from the scene of the accident to the emergency room	30–60(min)	9(40.9%)	0(0%)	1(50%)	0.685
	60–120(min)	13(59.1%)	1(100%)	1(50%)
	Total	22(100%)	1(100%)	2(100%)
How to transfer	Direct transfer from the scene of the accident to the hospital	4(18.2%)	0(0%)	0(0%)	0.723
	Indirect transmission	18(81.8%)	1(100%)	2(100%)
	Total	22(100%)	1(100%)	2(100%)

Discussion

This single-center, cross-sectional census study provides baseline data on the epidemiology, pre-hospital transport intervals, injury severity patterns, and hospital outcomes of all HEMS-transported trauma patients in Kermanshah Province.

Trauma remains a paramount public health and economic challenge worldwide, representing the leading cause of death and disability among individuals aged 1–40 years [23]. In developing nations, including Iran, trauma ranks as the second leading cause of mortality among young populations, placing an immense burden on healthcare infrastructure [24]. Efficient pre-hospital care and rapid specialized transport are vital components of secondary prevention to mitigate preventable mortality [25]. While HEMS expand geographic reach and facilitate rapid evacuation [26], empirical evaluations of HEMS trauma epidemiology and clinical outcomes in Iran remain limited [27].

In this census study of 25 HEMS trauma patients transported to Taleghani Hospital in 2022, road traffic accidents (50%) and falls > 3 m (25%) emerged as the predominant mechanisms of injury, with multiple injuries (polytrauma, 25%) and severe/very severe trauma (25%) driving HEMS activation. The overall mortality rate was 8% (n = 2), and the mean hospital length of stay was 15.5 ± 2.41days.

Trauma mechanisms and regional topography

The high prevalence of high-energy traffic collisions and high-altitude falls aligns with international and regional HEMS literature [28]. However, the specific mechanism profile reflects the unique geographical landscape of Kermanshah Province. The frequent occurrence of incidents in remote and rural counties such as Salas-e Babajani (35%) and Kermanshah County (40%) highlights the critical role of air medical evacuation in rugged, mountainous terrains. Unlike low-energy ground slips typical in urban cohorts [29], falls triggering HEMS in this study were exclusively high-energy falls from heights (e.g., roofs, high trees, hillsides), which significantly correlated with polytrauma and severe trauma (P < 0.05). This finding mirrors results by Ghaffarzad et al. in East Azerbaijan Province and Blok et al. (2024), where HEMS utilization was tightly coupled with high-energy mechanisms in topographically challenging zones [2, 3].

Demographic patterns and severity associations

Males constituted three-quarters (75%) of the total patient population, consistent with global patterns of outdoor employment, motor vehicle operation, and high-risk behaviors [30, 31]. Interestingly, analytical analyses revealed that trauma severity and specific injury sites (head trauma and polytrauma) were significantly higher among female patients (P < 0.05). While men had higher total exposure, females who suffered injuries severe enough to warrant aerial evacuation presented with disproportionately higher injury severity. This contrast suggests that HEMS activation for female patients occurred primarily during extreme, high-energy events (such as severe vehicular crashes or major falls in agricultural/rural settings), rather than minor trauma.

Transfer metrics and mortality determinants

The mean scene-to-hospital transfer time was 75.25 ± 22.52 min, with 80% being primary scene dispatches and 20% secondary inter-hospital transfers. Compared to ground ambulance networks, air emergency response times can be prolonged by pre-flight preparation, indoor helicopter stationing, weather assessments, and flight coordination, as noted by Al-Thani et al. in Qatar and Lapidus et al. in Sweden [18, 29]. Importantly, neither scene-to-hospital transfer duration (P > 0.05) nor dispatch type (P > 0.05) demonstrated a statistically significant association with patient mortality. Instead, mortality (8%) was strictly associated with anatomical injury location (head trauma and polytrauma) and baseline trauma severity (severe/very severe ISS/RTS scores, P < 0.05). Both deceased patients presented with catastrophic anatomical disruptions, including severe intracranial hemorrhages, massive free fluid, and refractory shock, reflecting that initial physiological damage rather than transport transit time alone remains the primary determinant of survival in major trauma [32–35].

Methodological context and clinical-policy implications

These findings carry direct clinical and policy implications for optimizing regional pre-hospital emergency care while providing essential context for interpreting the study’s scope. Given that polytrauma (25%) and severe head injuries were the primary drivers of mortality (P < 0.05), HEMS crews must be equipped for advanced airway management, rapid blood product transfusion, and invasive stabilization before and during transit. Furthermore, the lack of outcome differentiation between primary scene responses (80%) and secondary inter-hospital transfers (20%) supports maintaining HEMS as a flexible, dual-purpose asset serving both immediate remote scene response and urgent inter-facility transport from peripheral hospitals that lack specialized neurosurgical or trauma capabilities. A key strength of this evaluation is its complete annual census design, capturing all HEMS trauma transports to the primary tertiary referral center in Kermanshah Province and establishing critical baseline data on pre-hospital transport intervals, injury severity scoring (ISS and RTS), and mortality determinants in a mountain region. Nevertheless, these insights should be interpreted alongside inherent methodological constraints, including a small sample size (n = 25) that reflects total annual HEMS volume but limits statistical power for multivariable regression modeling, as well as a cross-sectional, single-center design with retrospective registry data that carries potential information bias and precludes direct causal comparisons against ground-ambulance transportation.

Conclusion

The findings demonstrate that male patients constituted the majority of air transfers (75%), with road traffic accidents (50%) and falls exceeding 3 m (25%) serving as the primary trauma mechanisms, and polytrauma (25%) representing the main presentation. Overall mortality (8%) was significantly associated with severe or very severe trauma scores and specific anatomical injury locations (head trauma and polytrauma, P < 0.05), whereas scene-to-hospital transfer durations and dispatch types (primary vs. secondary) showed no statistically significant association with mortality outcomes (P > 0.05).

Clinically, these findings highlight the necessity for HEMS pre-hospital teams to prioritize specialized stabilization for polytrauma and severe head injuries, while supporting the operational utility of HEMS for both direct scene responses and secondary inter-facility transfers in topographically challenging areas. Given the single-center, retrospective design and small sample size, these descriptive associations do not establish causal relationships. To build upon these baseline metrics and inform national pre-hospital protocol optimization, prospective, multicenter studies with larger cohorts and direct comparisons between air and ground transportation are recommended.

Abbreviations

HEMS

Helicopter emergency medical services

ISS

Injury Severity Score

RTS

Revised Trauma Score

RTAs

Road traffic accidents

ICD

International Classification of Diseases

SBP

Systolic blood pressure

GCS

Glasgow Coma Scale

GEMS

Ground emergency medical services

ICU

Intensive Care Unit

Author contributions

BR: Conceptualization, Methodology, Software MP and MRR: Data curation, Writing- Original draft preparation BR: Visualization, Investigation. MP: Supervision: MRR: Software, Validation.: MP: Writing- Reviewing and Editing,

Funding

There are no sources of funding to declare.

Data availability

The data and supportive information are available within the article.

Declarations

Human ethics and consent to participate

The study adhered to the principles of the Declaration of Helsinki. Ethical approval for this study was obtained from the Institutional Review Board (IRB) at the Kermanshah University of Medical Sciences (ID Number: IR.KUMS.MED.REC.1402.195). All participants provided informed consent. The data were maintained confidential throughout data collection and analysis.

Consent for publication

Not applicable.

Use of artificial intelligence tools

During the preparation of this manuscript, the authors used ChatGPT and Grammarly for language editing and grammar checking. All content was reviewed and edited by the authors, who take full responsibility for the accuracy and integrity of the manuscript.

Competing interests

The authors declare no competing interests.