The Impact of Intoxication on the Prognosis of High-Speed Motor Vehicle Accidents: A Tertiary Care Center Experience

Abstract

Introduction:

Several studies suggest a causal link between psychoactive agents and motor vehicle accidents (MVA). This study aimed to evaluate the impact of substance abuse and alcohol intoxication on the prognosis of high-speed MVA victims.

Methods:

This is a single-center retrospective cross-sectional study involving adult multiple trauma cases who were admitted to the emergency department for high-speed MVA and underwent toxicological screening. The cohort was conducted based on two main outcomes; the survival status and the neurological outcomes.

Results:

894 patients with the mean age of 27.8 ± 9.24 (range:18-37) years were studied (97.9% male). The most common indicators of severity were car rollover and ejection from the car. 296 of the patients had severe traumatic brain injury (TBI). 622 of the patients had a positive toxicological screening, with benzodiazepines (51.2%) and alcohol (26.6%) being the most commonly abused substances. The mortality rate was 5.8% and 12.1% of the patients had unfavorable neurological outcomes upon discharge. On multivariate logistic regression, predictors of mortality among high-speed MVA victims were report of a death at the scene (adjusted odds ratio (aOR): 2.529; 95% confidence interval (CI): 1.026-6.232; p = 0.044), severe TBI, the presence of dilated pupils (aOR: 11.074; 95% CI: 1.293-94.812; p = 0.028), hypotension (aOR: 0.456; 95% CI: 0.227-0.916; p = 0.027), and hypoxia (aOR: 2.95; 95% CI: 1.46-5.95; p = 0.003). Predictors of unfavorable neurological outcomes were report of a death at the scene (aOR: 3.133; 95% CI: 1.445-6.791; p = 0.004), positive toxicology screening (aOR: 3.30; 95% CI:1.68-10.204; p = 0.038), severe TBI, the presence of hypoxia (aOR: 2.96; 95% CI:1.645-5.319; p = 0.000), hypotension (aOR: 0.437; 95% CI: 0.252-0.758; p = 0.003), and bleeding (aOR: 0.287; 95% CI: 0.164-0.501; p < 0.001).

Conclusion:

A concerning proportion of high-speed MVA victims had a positive toxicology screening. Although intoxication did not increase mortality of high-speed MVAs, it was a significant predictor of unfavorable neurological outcomes of survivors.

1. Introduction:

Motor vehicle accidents (MVAs) remain a significant cause of morbidity and mortality worldwide, with an estimated annual death rate of 1.3 million (1). The burden of MVAs extends beyond the injured individuals and their families; it also significantly impacts the healthcare system responsible for their care (1, 2). In the Kingdom of Saudi Arabia (SA), the statistics concerning the burden of MVAs are particularly alarming, despite the implementation of road safety measures. Reports indicate that 20% of hospital admissions and 81% of deaths in Ministry of Health Hospitals are related to MVAs, with approximately four individuals injured every hour (3, 4) SA has the highest accident-to-injury ratio of 8:6, compared to 8:1.8 worldwide (4).

Alcohol and psychoactive substances, including amphetamines, cocaine, and cannabis, are known to adversely affect alertness, coordination, mood, memory, and judgment (5). Additionally, some substances, such as cannabis, may induce psychosis (5-7). Driving under the influence of these substances is a tragedy in its own right, as their negative effects on cognition and psychomotor function contribute significantly to MVAs (8). Beyond alcohol, cannabis is the most frequently detected substance in MVA-related morbidity and mortality, followed by benzodiazepines, opioids, cocaine, and amphetamines, accounting for 32%, 15%, 11.5%, 11%, and 6%, respectively (9).

Toxicology screening in high-speed MVA cases suspected of intoxication is crucial, as it poses serious public health and safety concerns (1, 10). Notably, the rate of opioid detection in victims of fatal MVAs has tripled from 2001 to 2016. Additionally, the rate of detecting multiple drugs in victims of fatal MVAs has increased by 10% from 1993 to 2010 (2). Despite these concerning statistics, Christophersen and Gjerde et al. reported that only 63% of fatal MVA victims were screened for alcohol and other substances of abuse (11, 12). Moreover, in Arizona, testing for blood alcohol concentration and substances of abuse in non-fatal MVA victims was performed in only 42% and 16% of cases, respectively (5).

Numerous studies have investigated this issue (5, 8, 9, 13-15). For example, a study involving 921 drivers in fatal MVAs in Canada found that alcohol or psychoactive agents were detected in 53.7% of subjects, with polysubstance use being positive in approximately 38% of cases. Drivers who tested positive for psychoactive drugs were more likely to have been involved in multi-vehicle accidents (13). Another study conducted in Norway reported a significantly higher prevalence (24%) of alcohol and/or other substances of abuse in drivers of fatal casualties compared to surviving drivers of MVAs (4%)(14). A retrospective study estimating the risk of fatalities among intoxicated drivers revealed that the crude mortality rates were highest for alcohol-intoxicated drivers, with MVAs accounting for 1% of deaths in alcohol and opioid cases and 4.1% in methamphetamine cases (9).

As highlighted, several studies suggest a causal link between psychoactive agents and MVAs. Data indicate that the combination of two or more psychoactive agents or psychoactive agents with alcohol increases the risk of accidents (15). The fact that Saudi Arabia has a higher accident-to-injury ratio than the international average, despite implementing appropriate road safety measures, underscores the need for further studies to investigate the underlying causes of this problem (3). Unfortunately, local studies addressing this issue are limited, making it imperative to evaluate whether intoxicated victims have worse prognoses compared to non-intoxicated victims in high-speed MVAs in SA. This study aimed to evaluate the impact of substance abuse and alcohol intoxication on the prognosis of high-speed motor vehicle accident (MVA) victims.

2. Methods:

2.1 Study design and setting

This was a single-center retrospective cohort study conducted at King Abdulaziz Medical City (KAMC), Department of Emergency Medicine, Ministry of National Guard-Health Affairs, Riyadh, SA. The cohort was conducted based on two main outcomes; the survival status and the neurological outcomes.

KAMC is an academic government-funded tertiary hospital that combines clinical care, training, academics with research, and state-of-the-art medical technologies.

The study was approved by the Institutional Review Board of King Abdullah International Medical Research Center, Ministry of National Guard-Health Affairs, Riyadh, SA (NRC22R/105/02). Informed consent was waived because of the retrospective nature of this study. Access to the data was restricted to the researchers. The confidentiality of all patients was protected, and no names or medical record numbers were used. Privacy and confidentiality were assured, and all the hard and soft copies of data were kept in a secure place within the Ministry of National Guard-Health Affairs premises. This study complies with the Declaration of Helsinki.

2.2 Participants

All adults aged 18 years or older who were admitted to the emergency department (ED) for high-speed MVA and underwent toxicological screening from 2016 to 2022 were included in the study. Those transferred from other hospitals were excluded. Patients with significant missing data compromising the accuracy of the results, such as Glasgow Coma Scale (GCS) scores or toxicological results, were excluded to maintain the integrity of the analysis. However, if a patient had minor missing data that did not impact the main outcomes of interest, they were included in the analysis.

Additionally, MVA victims who tested positive for substances on toxicological screening but had valid prescriptions for opioids, benzodiazepines, or stimulants for medically justified reasons were also excluded to minimize confounding factors that could independently influence neurological function and recovery outcomes.

2.3 Data gathering

The required data were obtained by screening the electronic medical records (via the KAMC electronic system “BestCare” Seoul, South Korea: ezCaretech Co) of all the patients who met the inclusion criteria. The following data were collected: age, gender, mode and time of arrival to the ED, extent of the injury, GCS on arrival, pupil size, the presence of cerebral hemorrhage, hypotension (defined as systolic blood pressure below 90 mmHg), or hypoxia (defined as O₂ saturation below 90% and/or arterial O₂ tension of less than 80 mmHg), Rotterdam computed tomography (CT) score, toxicological screening results, intensive care unit (ICU) admission and length of stay, the need for intubation and mechanical ventilation, survival status, and neurological function at discharge for alive individuals. The GCS was used to classify the severity of traumatic brain injury (TBI) into mild (15-13), moderate (12-9), and severe (8-3) TBI.

Favorable neurological outcomes were defined as complete neurological recovery or a residual neurological deficit that does not significantly affect functional independence at discharge. Unfavorable neurological outcomes were defined as permanent neurological dysfunction that affects functional independence or decreases awareness or responsiveness to stimuli.

2.4 Statistical analysis

The Statistical Package for the Social Sciences (SPSS version 27; IBM Co., Armonk, NY, USA) was used for data analysis. Continuous variables were checked for normality and are presented as a mean ± standard deviation. Categorical variables are presented as a frequency and percentage. The Fisher's exact test was used to compare categorical variables. Two binary logistic regression analyses were conducted to identify predictors of death and neurological status among high-speed MVA victims. The factors considered in the analyses were categorized as predictors, with "Alive" and “Favorable neurological outcome” serving as the reference categories. The adjusted odds ratios (aOR), with a 95% confidence interval (CI), and corresponding p-values were calculated for each predictor. For this purpose, univariate analysis was carried out, and the significant factors were included in the final multivariate model. All reported p-values are two-tailed, and a p < 0.05 was considered statistically significant.

3. Results:

3.1 Baseline characteristics of studied patients

A total of 894 high-speed MVA victims who underwent toxicological screening were eligible for inclusion. The majority (97.9%; n = 875) of the patients were males, with a mean age of 27.8 ± 9.24 years and an average hospital length of stay of 17.53 ± 44.46 days. Table 1 presents the baseline characteristics of the study population. Over three-quarters (91.5%; n = 818) of the patients arrived at the emergency department (ED) via emergency medical services (EMS). Blunt injuries accounted for 96% (n = 855) of the injuries, with car rollover being the most common indicator of severity (21.6%), followed by ejection from the car (18.3%), death at the scene (6.9%), and falls from significant heights (1.7%). Nearly three-quarters (74.4%; n = 665) of patients had a Rotterdam CT score of 1. Severe traumatic brain injury (TBI) was observed in 33.1% (n = 296) of the patients, and only 6.2% (n = 55) presented with fixed dilated pupils. Positive toxicological screening was noted in 77.5% (n = 622) of patients, with the most abused substances being benzodiazepines (51.2%; n = 414) and alcohol (26.6%; n = 237). Other substances included cannabis (24.4%), amphetamines (21.1%), and opioids (14%) (Figure 1). The mortality rate among the study population was 5.8%, with 82.1% (n = 734) of survivors achieving favorable neurological outcomes at discharge.

Table 1.

Baseline characteristics of studied patients

Variable	Value	Variable	Value
Age (year)		Length of stay (day)
Mean ± SD	27.83 ± 9.24	Mean ± SD	17.53 ± 44.46
Gender		TBI severity
Male	875 (97.9)	Mild	499 (55.8)
Female	19 (2.1)	Moderate	99 (11.1)
Arrival time		Severe	296 (33.1)
7 AM to 3 PM	284 (31.8)	Pupils
3 PM to 11 PM	224 (25.1)	Reactive bilateral	707 (79.1)
11 PM to 7 AM	386 (43.2)	Sluggish + non-reactive	81 (9.1)
Mode of injury		Unequal pupil sizes	21 (2.3)
Blunt	855 (96.0)	Dilated pupils	55 (6.2)
Penetrating	36 (4.0)	Constricted pupils	30 (3.4)
Mode of Arrival		Toxicology screening
By EMS	818 (91.5)	Negative	181 (22.5)
By family	76 (8.5)	Positive	622 (77.5)
Indicators of severity		Intoxication with
Roll over	193 (21.6)	Cocaine	7 (0.9)
Ejected from the car	164 (18.3)	Amphetamine	170 (21.1)
Fall from significant height	15 (1.7)	Barbiturate	5 (0.6)
Death at scene	62 (6.9)	Opioids	113 (14.0)
Other	478 (53.5)	Benzodiazepines	414 (51.2)
Outcome		Methanol	41 (4.6)
Favorable neurological outcome	734 (82.1)	Ethanol	196 (21.9)
Unfavorable neurological outcome	108 (12.1)
Death	52 (5.8)

Data are presented as mean ± standard deviation (SD) or number (%). TBI: Traumatic Brain Injury; EMS: Emergency Medical Services.

Figure 1.

The percentage of detected substances in toxicological screening of high-speed motor vehicle accidents (MVA) victims in descending order. The most commonly detected substance was benzodiazepine, and it was the only one that could significantly predict unfavorable neurological outcomes among high-speed MVA victims (p < 0.001).

3.2 Predictors of survival

Table 2 compares the baseline characteristics of studied patients between survived and non-survived cases (univariate analysis). The mode of arrival (p = 0.018), ejection from the car (p = 0.009), severe TBI (p < 0.001), fixed dilated pupils (p < 0.001), hypoxia (p < 0.001), hypotension (p < 0.001), and intracranial hemorrhage (p < 0.001) were significantly associated with survival. Drug intoxication did not show a significant association with mortality, trends were noted for benzodiazepines (92.8% vs. 95.4%, p = 0.136) and opioids (97.3% vs. 93.5%, p = 0.134), providing valuable insight into the potential role of these substances.

Table 2.

Comparing the baseline characteristics of studied cases between survived and non-survived patients

Variable	Survived (n = 842)	Non-survived (n= 52)	P
Gender
Male	824 (94.2)	51 (5.8)	1.000
Female	18 (94.7)	1 (5.3)
Arrival time
7 AM to 3 PM	266 (93.7)	18 (6.3)	0.222
3 PM to 11 PM	207 (95.6)	17 (7.6)
11 PM to 7 AM	369 (93.6)	17 (4.4)
Mode of arrival
By EMS	766 (93.6)	52 (6.4)	0.018
By family	76 (100.0)	0 (0.0)
Indicators of severity
Roll over	179 (92.7)	14 (7.3)	0.384
Ejected from the car	147 (89.6)	17 (10.4)	0.009*
Fall from significant height	14 (93.3)	1 (6.7)	0.596
Report of death at Scene	53 (85.5)	9 (14.5)	0.007*
GCS
Mild	490 (98.2)	9 (1.8)	<0.001*
Moderate	97 (98.0)	2 (2.0)
Severe	255 (86.1)	41
Pupils
Reactive bilateral	681 (96.3)	26 (3.7)	<0.001*
Sluggish + non-reactive	76 (93.8)	5 (6.2)
Difference between pupils	18 (85.7)	3 (14.3)
Dilated pupils	38 (69.1)	17 (30.9)
Constricted pupils	29 (96.7)	1 (3.3)
Clinical/imaging findings
Hypoxia	102 (80.3)	25 (19.7)	<0.001*
Hypotension	158 (87.3)	23 (12.7)	<0.001*
Intracranial hemorrhage1	205 (89.1)	25 (10.9)	<0.001*
Acute mass lesion evacuation	34 (87.2)	5 (12.8)	0.070
Toxicology screening
Cannabis	185 (93.9)	12 (6.1)	0.864
Cocaine	7 (100.0)	0 (0.0)	1.000
Amphetamine	163 (95.9)	7 (4.1)	0.360
Barbiturate	5 (100.0)	0 (0.0)	1.000
Opioids	110 (97.3)	3 (2.7)	0.134
Benzodiazepines	384 (92.8)	30 (7.2)	0.136
Methanol	40 (97.6)	1 (2.4)	0.506
Ethanol	187 (95.4)	9 (4.6)	0.491
Total	592 (95.2)	30 (4.8)	0.699

Data are presented as number (%). 1: Epidural/Subdural or Sub-Arachnoid Hematoma; EMS: Emergency Medical Services; GCS: Glasgow Coma Scale.

In binary logistic regression analysis (Table 3), involvement in a high-speed MVA with report of death at the scene significantly increased the odds of mortality (adjusted odds ratio [aOR] = 2.529, 95% CI: 1.026-6.232, p = 0.044). Patients with mild (aOR = 0.226, 95% CI: 0.94-0.544, p = 0.001) or moderate TBI (aOR = 0.158, 95% CI: 0.36-0.697, p = 0.015) had significantly lower odds of death compared to those with severe TBI. Additionally, patients with fixed dilated pupils had significantly higher odds of death (aOR = 11.074, 95% CI: 1.293-94.812, p = 0.028). The absence of hypoxia (aOR = 0.339, 95% CI: 0.168-0.684, p = 0.003) and hypotension (aOR = 0.456, 95% CI: 0.227-0.916, p = 0.027) were associated with significantly lower odds of death.

Table 3.

Binary Logistic Regression for independent predictors of survival (Reference: Alive) and unfavorable neurological outcome (Reference: alive with favorable neurological outcome) following motor vehicle accidents (N=894)

Factors	AOR	95% CI		P value
		Lower	Upper
Independent predictors of survival
Trauma severity indicator
Ejected from the car	1.364	0.678	2.743	0.384
Death at scene	2.529	1.026	6.232	0.044
TBI severity
Mild	0.226	0.094	0.544	0.001
Moderate	0.158	0.036	0.697	0.015
Severe	Ref	Ref	Ref	Ref
Pupils
Reactive bilateral	2.415	0.298	19.546	0.409
Sluggish + non-reactive	1.346	0.142	12.717	0.796
Difference between pupils	2.904	0.260	32.481	0.387
Dilated pupils	11.074	1.293	94.812	0.028
Constricted pupils	Ref	Ref	Ref	Ref
Clinical/imaging findings
No hypoxia	0.339	0.168	0.684	0.003
No hypotension	0.456	0.227	0.916	0.027
No intracranial hemorrhage1	0.761	0.382	1.516	0.438
Independent predictors of unfavorable neurological outcome
Mode of arrival
By EMS	2.005	0.455	8.845	0.358
Trauma severity indicator
Report of a death at scene	3.133	1.445	6.791	0.004
GCS
Mild	0.530	0.289	0.975	0.041
Moderate	0.508	0.233	1.107	0.088
Severe	Ref	Ref	Ref	Ref
Pupils
Reactive bilateral	2.029	0.525	7.845	0.305
Sluggish + non-reactive	0.689	0.152	3.125	0.629
Difference between pupils	2.332	0.415	13.111	0.337
Dilated pupils	1.803	0.337	9.638	0.491
Constricted pupils	Ref	Ref	Ref	Ref
Clinical/imaging findings
No hypoxia	0.338	0.188	0.608	0.000
No hypotension	0.437	0.252	0.758	0.003
No intracranial hemorrhage	0.287	0.164	0.501	0.000
No acute mass lesion evacuation	0.425	0.175	1.031	0.058
Intoxication
Negative toxicology screening	0.303	0.098	0.936	0.038
Positive benzodiazepines	0.914	0.522	1.601	0.754
With Methanol				0.052
Negative	0.218	0.015	3.255	0.270
2.2 to 10	0.618	0.037	10.448	0.739
More than 30	Ref	Ref	Ref	Ref

AOR: Adjusted Odds Ratio; CI: Confidence interval for AOR; TBI: Traumatic Brain Injury; EMS: Emergency Medical Services; GCS: Glasgow Coma Scale.1: Epidural/subdural or sub-arachnoid hematoma.

3.3 Predictors of unfavorable neurological outcome

Table 4 compares the baseline characteristics of studied patients between cases with and without unfavorable neurological outcome (univariate analysis). The mode of arrival (p = 0.003), severe TBI (p < 0.001), fixed dilated pupils (p = 0.006), hypoxia (p < 0.001), hypotension (p < 0.001), and intracranial hemorrhage (p < 0.001) were significantly associated with unfavorable neurological outcome. Positive toxicology screening was significantly associated with unfavorable neurological outcomes (16.0% vs. 5.2%, p < 0.001), with benzodiazepine intoxication showing a marked association (unfavorable: 18.2% vs. 8.5%, p < 0.001).

Table 4.

Comparing the baseline characteristics of studied patients between cases with and without unfavorable neurological outcome

Variable	Unfavorable neurological outcome		P
	No (n = 734)	Yes (n = 108)
Gender
Male	716 (86.9)	108 (13.1)	0.151
Female	18 (100.0)	0 (0.0)
Arrival time
From 7 AM to 3 PM	233 (87.6)	33 (12.4)	0.973
From 3 PM to 11 PM	180 (87.0)	27 (13.0)
From 11 PM to 7 AM	321 (87.0)	48 (13.0)
Mode of arrival
By EMS	660 (86.2)	106 (13.8)	0.003*
By family	74 (97.4)	2 (2.6)
Indicators of severity
Roll over	152 (84.9)	27 (15.1)	0.315
Ejected from the car	125 (85.0)	22 (15.0)	0.415
Fall from significant height	13 (92.9)	1 (7.1)	1.000
Report of death at Scene	40 (75.5)	13 (24.5)	0.017*
GCS
Mild	458 (93.5)	32 (6.5)	<0.001*
Moderate	84 (86.6)	13 (13.4)
Severe	192 (75.3)	63 (24.7)
Pupils
Reactive bilateral	602 (88.4)	79 (11.6)	0.006*
Sluggish + non-reactive	64 (84.2)	12 (15.8)
Difference between pupils	10 (55.6)	8 (44.4)
Dilated pupils	32 (84.2)	6 (15.8)
Constricted pupils	26 (89.7)	3 (10.3)
Clinical/imaging findings
Hypoxia	69 (67.6)	33 (32.4)	<0.001*
Hypotension	121 (76.6)	37 (23.4)	<0.001*
Intracranial hemorrhage1	146 (71.2)	59 (28.8)	<0.001*
Acute mass lesion evacuation	20 (58.8)	14 (41.2)	<0.001*
Toxicology screening
Cannabis	161 (87.0)	24 (13.0)	0.902
Cocaine	6 (85.7)	1 (14.3)	1.000
Amphetamine	141 (86.5)	22 (13.5)	1.000
Barbiturate	4 (80.0)	1 (20.0)	0.515
Opioids	95 (86.4)	15 (13.6)	1.000
Benzodiazepines	314 (81.8)	70 (18.2)	<0.001*
Methanol	29 (72.5)	11 (27.5)	0.012*
Methanol	29 (12.1)	11 (87.9)	0.016*
Ethanol	165 (88.2)	22 (11.8)	0.710

Data are presented as numbers (%).1: Epidural/Subdural or Sub-Arachnoid Hematoma; EMS: Emergency Medical Services; GCS: Glasgow Coma Scale.

Based on binary logistic regression analysis (Table 3), high-speed MVA involving death at the scene were correlated with unfavorable neurological outcomes (aOR = 3.133, 95% CI: 1.445-6.791, p = 0.004). The absence of hypoxia (aOR = 0.338, 95% CI: 0.188-0.608, p < 0.001), hypotension (aOR = 0.437, 95% CI: 0.252-0.758, p = 0.003), and intracranial hemorrhage (aOR = 0.287, 95% CI: 0.164-0.501, p < 0.001) were associated with significantly lower odds of unfavorable neurological outcomes. Additionally, patients with a negative toxicology screening had lower odds of unfavorable neurological outcomes (aOR = 0.303, 95% CI: 0.098-0.936, p = 0.038), while those with mild TBI had significantly lower odds of unfavorable outcomes compared to severe TBI (aOR = 0.530, 95% CI: 0.289-0.975, p = 0.041).

6. Declarations:

All authors declare no conflicts of interest in this work.

Data availability

The dataset used and/or analyzed in the current study is available upon request.

Author contributions

All authors made a significant contribution to the work reported, whether that is in the conception, study design, execution, acquisition of data, analysis and interpretation, or in all these areas; took part in drafting, revising or critically reviewing the article; gave final approval of the version to be published; have agreed on the journal to which the article has been submitted; and agree to be accountable for all aspects of the work.

Funding

There is no funding to report.

Acknowledgement

None.

Using artificial intelligence chatbots

There was no use of artificial intelligence in the making of this article.