Consequences of Traffic Accidents Transferred by Helicopter and Ground Ambulance: Propensity Score Matching

Introduction: The main task of the emergency medical system is to provide primary care and transfer the injured to a medical center.  Studies have been conducted to investigate the outcome of helicopter and ground ambulance casualties, but they show different results.  These different results may be due to the type of study, statistical methods, differences in pre-hospital emergency systems, and insufficient control of confounding variables, which make it difficult to compare and generalize the results.  This study aimed to investigate the consequences of injured people transported by helicopter and ground ambulance in road traffic accidents in Qom province 2015-2018.  Methods: In this retrospective analytical descriptive study, all road traffic accident victims who were transferred to Qom Shahid Beheshti Medical Center by pre-hospital emergency by land or air during the period 2015 to 2018 were examined by numerical method.  The collected information included the type of transfer, age, sex, type of trauma, distance from the accident site to the medical center, initial vital signs, duration of the mission, and day of the accident.  To control the confounding factors, Propensity Score Matching was used.  Outcomes studied included length of hospital stay, length of stay in the intensive care unit, duration of mechanical ventilation, and the need for urgent surgery.  Logistic regression for statistical analysis of the need for immediate surgery and other consequences, a generalized linear model was used.  Results: After matching, the number of injured in each group of ground ambulances and helicopters was 566.  Trauma to the head (P = 0.028) and back (P = 0.002) were more common in helicopter-transported casualties.  The injured transported by helicopter had a longer time to reach the scene (7.70 ±5.18) (P <0.001), a shorter duration of presence on the scene (12.17 ± 8.33) (P = 0.041), and a shorter duration of transmission  (13.12 ± 4.75) (P <0.001) than the ground ambulance. There was no significant difference between the length of hospital stay in the intensive care unit (P = 0.718), mechanical ventilation (P = 0.507), and hospitalization (P = 0.089) in the injured by ground and helicopter ambulance. The need for immediate surgery in helicopter-transported casualties was 84.8% higher than ground ambulance casualties (95% CI: 0.086-0.267) (P <0.001).  Conclusion: The injured transported by helicopter during hospitalization in the intensive care unit, mechanical ventilation, and hospitalization were not significantly different, but more needed immediate surgery.  If the injured are properly triaged according to the type of injury and the level of consciousness on the scene and transferred to the appropriate medical center by land or air transfer, they can enjoy the benefits of the type of transfer.