Neurological Outcomes in Traffic Accidents: A Propensity Score Matching Analysis of Medical and Non-Medical Origin Cases of Out-of-Hospital Cardiac Arrest
Authors: Miyashita Yumiko , Toyama Gen , Takahashi Tsukasa , Adachi Tetsuhiro , Omatsu Kentaro , Ozaki Akane , Takei Yutaka 
Published: August 2023

Abstract
Aim: This study aimed to compare the characteristics of out-of-hospital cardiac arrest cases attributed to traffic accidents, distinguishing between medical and non-medical origins, and to explore the potential association between cases with a medical origin and a neurologically favourable outcome.
Methods: We analysed 5,091 cases of traffic accidents that occurred between 2018 and 2020, classifying patients into two groups based on the Utstein style. The causes of arrest were categorized into cardiac and non-cardiac origins, with non-cardiac cases further subdivided into cerebrovascular events, traffic-related trauma, and other causes. Instances diagnosed by physicians as resulting from traffic-related trauma were labeled as "non-medical origin," while the remainder were classified as "medical origin.".
Results: Medical-origin cases exhibited several distinct characteristics, including higher frequencies of occurrence during the daytime (79.3% [706/890] vs. 68.9% [2,895/4,201], p < 0.001), a higher prevalence among male (77.8% [692/890] vs. 68.3% [2,871/4,201], p < 0.001) and younger patients (median [25–75%]: 63 years [42–77] vs. 66 years [50–76], p = 0.003), a higher proportion of shockable initial rhythms(10.5% [93/890] vs. 1.1% [45/4,201], p < 0.001), an increased number of cases requiring advanced airway management (33.8% [301/890] vs. 28.5% [1,199/4,201], p = 0.002) and adrenaline administration by emergency medical teams (26.9% [239/890] vs. 21.7% [910/4,201], p < 0.001), and shorter transport times (55.3% [492/890] vs. 60.9% [2,558/4,201], p = 0.002) compared to non-medical-origin cases. However, medical-origin cases also demonstrated lower witness rates (42.8% [381/890] vs. 27.2% [1,142/4,201], p < 0.001) and were less likely to be transported to higher-level hospitals (55.3% [492/890] vs. 60.9% [2,558/4,201], p = 0.002). Propensity score matching analysis identified factors associated with favourable neurological outcomes in traffic accidents with medical-origin cases. The odds ratios were as follows: 8.46 (3.47–20.61) for cases with shockable initial rhythms, 2.36 (1.01–5.52) for cases involving traffic accidents due to medical origin, and 0.09 (0.01–0.67) for cases where advanced airway management was not provided.
Conclusion: Medical-origin cases showed higher frequencies during the daytime, with a greater prevalence among male and younger patients, and a higher proportion of shockable initial rhythms. Additionally, these cases received more advanced airway management approaches and adrenaline but exhibited lower witness rates and were less likely to be transported to higher-level hospitals. This study identified factors associated with favourable neurological outcomes, including shockable initial rhythms, medical-origin accidents, and non-provision of advanced airway management. These findings will contribute to improving emergency medical care and accident management in medical-related traffic accidents.