Outcomes of Traffic Accident Patients Transferred by Air and Ground Ambulance: Propensity Score Matching

The main task of the emergency medical system is to provide primary care and transfer the patients to hospital. Studies have been conducted to investigate the outcome of air and ground ambulance patients, but they show different results. These different results may be due to the type of study, statistical methods, differences in prehospital emergency systems, and insufficient control of confounding variables. Thus, it is difficult to compare and generalize the results. This study aimed to investigate the outcomes of injured people transported by air and ground ambulance in road traffic accidents in Qom Province, Iran, during 2015-2019.

In this retrospective analytical descriptive study, we used the numerical method and examined all road traffic accident patients transferred through ground or air to Qom Shahid Beheshti Hospital by the prehospital emergency from 2015 to 2019. The collected information included the type of transfer, age, sex, type of trauma, distance from the accident site to the hospital, initial vital signs, duration of the mission, and day of the accident. To control the confounding factors, we used propensity score matching. Outcomes studied included length of hospital stay, length of stay in the intensive care unit, duration of mechanical ventilation, and the need for immediate surgery. Logistic regression was used to analyze the need for immediate surgery and a generalized linear model for other consequences.

After matching, the number of patients in each group transferred by ground ambulances and helicopter was 566. Trauma to the head (P=0.028) and back (P=0.002) were more common in helicopter-transported patients. The patients transported by helicopter had a longer time to reach the scene (7.70 ±5.18 min) (P<0.001), a shorter duration of presence on the scene (12.17±8.33 min) (P=0.041), and a shorter duration of transfer (13.12±4.75 min) (P<0.001) than the ground ambulance. There was no significant difference between the patients who transferred by ground and helicopter ambulance regarding the length of hospital stay in the intensive care unit (P=0.718), mechanical ventilation (P=0.507), and hospitalization (P=0.089). The need for immediate surgery in helicopter-transported patients was 84.8% higher than ground ambulance patients (95%CI: 0.086-0.267; P<0.001).

The patients transported by helicopter were not significantly different from ground ambulances transported patients regarding staying in the intensive care unit, mechanical ventilation, and hospitalization, but they more needed immediate surgery. If the patients are triaged adequately according to the type of injury and the level of consciousness at the scene and transferred to the appropriate hospital by ground or air, they can enjoy the benefits of the type of transfer.