Descriptive epidemiology of injuries with concomitant cannabis use among adolescents and young adults in the United States: a cross-sectional study

Introduction

With the evolving legalization landscape of cannabis for medicinal and recreational purposes in the United States (U.S.), the impact on public health and in particular, injuries, is of concern. At present, the majority of states in the U.S. have legalized cannabis for medical use, and statutes legalizing recreational use are expanding, with more legislation pending (1). Historically, cannabis usage rates in the U.S. have experienced notable fluctuations. While cannabis usage rates vary among different demographic groups and geographic regions, highlighting the complex dynamics that influence cannabis consumption (2), cannabis use has incurred unprecedented growth of late. Between 2011 and 2021, past year cannabis use among young adults aged 19–30 years increased from 29% to 43%, representing a 13.2% increase (3). Factors contributing to this rise include shifting perceptions of the risks associated with cannabis use, the influence of popular culture, and growing acceptance of the substance for medicinal purposes (1). With trends in use increasing, and methods of consumption and potency changing, it becomes important to continue to examine effects on public health. Cannabis use among adolescents and young adults has garnered significant attention due to its potential impact on cognitive and behavioral risks and potential for injury. Studies have consistently shown that early and heavy cannabis use during adolescence can lead to long-term cognitive deficits, including impairments in memory, attention, and executive function (4). These cognitive impairments may not only hinder academic and occupational achievements but also increase the likelihood of engaging in risky behaviors such as driving under the influence, thus elevating the risk of and injuries (5). Furthermore, The potency of modern cannabis products, characterized by higher concentrations of delta-9-tetrahyrdocannabinol (THC), further amplifies these risks, potentially exacerbating the likelihood and severity of adverse outcomes (6). Consequently, addressing the complex interplay between cannabis use, cannabis legislation, and social norming of use is crucial for mitigating the risks of injury and promoting the overall well-being of adolescents and young adults. Effective prevention and intervention strategies should prioritize early identification of at-risk individuals.

Research has been undertaken to investigate the relationship between cannabis use and injuries, aiming to determine the extent of the risk posed by impairment resulting from its consumption. Studies have specifically examined driving under the influence of cannabis and have most have found an association between cannabis use and an increased risk of motor vehicle crashes and/or driving impairment (7-10). Moreover, the impact of cannabis on motor vehicle collision risk can vary based on factors such as THC concentration, individual tolerance, and concurrent alcohol use (7). The introduction of legal recreational cannabis markets in some states has brought attention to the potential effects on crash rates, finding that traffic fatality rates may increase after cannabis legislation (9,11). However, inferring causality between cannabis use and motor vehicle crashes can be difficult as another layer of complexity arises from the frequent co-use of cannabis with alcohol, often referred to as “cross fading” (12). The combined effects of these substances can exacerbate impairment and increase the risk of injury, either additively or perhaps synergistically (9). In addition, issues such as differences in dosages, and difficulties in measuring acute impairment, burdens the research inquiry (8,9). These findings have significant implications for policymaking, as regulations must consider not only the legal status of cannabis but also its potential interaction with alcohol. In addition to traffic-related crashes and injuries, concerns have extended to workplace injuries. While the evidence is mixed, it highlights the broader implications of cannabis-induced impairment on occupational safety and productivity (13).

While the majority of studies examining cannabis’ impact on injuries have focused on motor vehicle crashes, as these events place both the user and public at risk for injury, there is a dearth of research examining other injuries that may be associated with cannabis use. To address this gap, we sought to examine adolescents and young adults who presented to an emergency department (ED) with an injury and concomitant cannabis use without adjuvant alcohol involvement. We present this article in accordance with the STROBE reporting checklist (available at https://jeccm.amegroups.com/article/view/10.21037/jeccm-24-37/rc).

Methods

We examined data from the 2019–2022 National Electronic Injury Surveillance System (NEISS) for cannabis-related ED episode visits. The NEISS is a nationally representative surveillance system, operated by the Consumer Products Safety Commission (CPSC), to collect data on ED visits related to injury and is publicly available. Beginning in 2019, NEISS began coding events that were drug or alcohol-related which provides for emerging surveillance for injury-related ED visits in which drugs and/or alcohol were a contributing factor. The patient population in NEISS are initial injury visits treated in hospital EDs (14).

Measures

Cases were limited to adolescents and young adults aged 15–24 years presenting to an ED for an unintentional injury-related event related to exposure to a cannabis product. To increase the specificity of the case definition, we analyzed whether or not the visit was drug-related and then subsequently examined the narrative text entries provided by the intake personnel which described in greater detail the precipitating event. To identify substance use-related injuries, personnel were trained and directed to provide on the ED intake report whether the patient “consumed alcohol prior to or during the incident,” and/or “whether the patient used a drug(s)…that contributed to the incident or the severity of the injury.” (15). Next, to include patients who had used cannabis, narrative text entries were screened for terms including “THC” “marijuana” “cannabis” and “mj” or various derivatives of those terms to capture abbreviations or misspellings using STATA’s screening procedure. Lastly, if the ED record indicated that alcohol contributed to the incident, those patients were then excluded from the study sample. The resulting sample included those patients presenting to an ED with an injury with concomitant cannabis use, but not alcohol. In the event a patient listed other recreational drugs besides cannabis use, they were also eliminated from the sample.

The mechanism of injury was determined by examining the narrative text entry of each case. Fewer than 1% of ED visits were due to non-injury (e.g., chest pain) and were eliminated. This resulted in the following categories of injury mechanism: fall, poisoning, self-inflicted via anger (e.g., punching a wall), wheeled transport other than automobile [bicycle, all terrain vehicle (ATV), scooter, etc.], and “other”. The “other” category included diffuse manner of injuries inclusive of cut/pierce, burns, and others that did not meet the number of cases needed to produce reliable estimates. Injuries included in the analyses included poisonings, internal injury, laceration, contusion, fractures, and other. Lastly, demographic variables included sex, age, race/ethnicity, as well as body part injured and patient disposition. The NEISS does not use ICD-10-CM coding. Rather, the CPSC utilizes its own coding system. Evaluation of comparability of the NEISS and ICD-9-CM coding scheme has shown favorable comparability between the two systems, particularly when case narratives are incorporated (16). However, comparability between NEISS and ICD-10-CM ontology systems have not been confirmed.

Statistical analysis

Descriptive epidemiological analyses were conducted using STATA/MP. To provide national estimates of the patient visits, sample weights were applied and sample design variables were incorporated into all analyses. Prevalence ratios (PRs) to assess rate differences were obtained from STATA’s margins command to calculate predictions from previously fitted logistic regression models to estimate differences in probability for cannabis-related injury between sex, age group, and race/ethnicity. Significance of trends over the 4-year study period was estimated using Joinpoint regression analyses (17). The Joinpoint regression model was fitted to estimate annual percent change (APC) in crude rates by year. Sample size estimates based on fewer than 20 raw cases (or 1,200 weighted cases), or which had a coefficient of variation equal to or greater than 30%, were considered unreliable (15).

Ethical considerations

The study was conducted in accordance with the Declaration of Helsinki (as revised in 2013). The study was approved by The University of Arkansas Institutional Review Board (IRB registration No. 0018463) and individual consent for this retrospective analysis was waived.

Results

During the study frame, there were an estimated 48.8 million visits for injuries to the ED in the U.S. Among this population, 24,922 ED visits were for injuries among adolescents and young adults who had used cannabis. Demographic characteristics of those injured indicated that the majority were male (64.3%) and White (46.9%). Falls were the most common reason for injury visits to the ED, with 37.0% of visits among the study sample related to falls. Poisonings accounted for 21.9% of ED visits associated with cannabis use, with violent self-harm episodes (e.g., punching a wall) and wheeled transportation other than cars/trucks (e.g., bicycles, skateboards, ATV’s, electric scooters, etc.) representing 10.8% and 9.9% of injuries, respectively.

Rate differences of cannabis-related injury visits were found to differ significantly between sex, race ethnicity groups, and age groups. Females were found to have a lower prevalence of cannabis associated injuries, as were black patients (when compared to white patients as the referent group). By age group, those aged 20–24 years presented with a higher prevalence of cannabis-related injury [PR =1.6, 95% confidence interval (CI): 1.18–2.02] when compared to those aged 15–19 years (Table 1).

Diagnoses associated with cannabis-related injuries were diffuse, with 21.9% classified as poisoning, 17.2% presenting with internal injuries, 8.5% presenting with fractures, and 9.5% with contusions. The majority of injuries occurred to the head and neck region (37.5%). With regard to patient disposition, 20.6% were admitted to the hospital or transferred to another medical facility. Three diagnoses contributed to the majority of hospital admissions, with 46.0% of all patients with fractures having been admitted/transferred, followed by 25.6% patients with internal injuries, and 17.6% of patients who presented with poisoning.

By year, the number of cannabis-related injuries seen in the ED tended to increase, with the greatest percentage of patient visits occurring in the years 2021 (28.2%) and 2022 (26.7%) (Table 1). Trends in rates of cannabis-related injuries increased during the study period, as depicted in Figure 1. Graphically, rates increased between 2019 and 2022 [APC =5.4 (95% CI: 4.8–5.9), P<0.05].

Figure 1 Trend in cannabis-related injury by year among adolescents and young adults, 2019–2022.

Discussion

The results of the study have several significant implications. The finding that there were an estimated 24,922 ED visits among adolescents and young adults related to cannabis use is concerning, especially when considering alcohol was not a co-contributing factor. This highlights the need for further research concerning the potential injury risks and adverse effects associated with cannabis consumption, especially fall injuries among this age group. We found an increasing trend in ED visits associated with cannabis use over time. Whether this trend is transitory or related to changes in policy and more permissive attitudes toward the drug is unclear, but warrants further investigation.

Falls were the predominant mechanism of injury among the sample. Falls were ubiquitous, and included falls from heights, fall on the same level, and falling on stairs. The likelihood of fall-related injuries may be influenced by the impairment of coordination, reaction time, and delayed information processing associated with cannabis use (18). Poisonings, anger-related self-harm episodes, and wheeled transportation crash injuries, were the other most prominent mechanisms of injury. A surprising finding was the frequency of injuries associated with anger related self-harm. Based on the narrative text information, anger-related self-harm was not indicative of a suicide attempt. Rather these were anger-induced injuries such as “banged his head against a wall”, and “punched a wall” after becoming angry. Analyses of the narrative text did not indicate that self-harm with suicide as the intent was a common injury. Poisonings typically involved a negative reaction to cannabis use, such a hyperemesis, as noted in the narrative text entries.

The variety of diagnoses associated with cannabis-related injury visits, including poisoning, internal injuries, fractures, and contusions, indicates the wide range of potential harms depending on the mechanism of injury. Cannabis potentially contributed not only to the injury incident, but also to the severity of these injuries, if the persons reflexes were impaired and they were unable to brace a fall, for example. In relation, approximately 20% of the injured individuals were admitted to the hospital or transferred to another medical facility. This highlights the severity of some of the injuries and the burden they may place on the healthcare system. Not surprisingly, head and neck injuries were the predominant body part injured, as persons with injuries to those parts of the body may be more likely to seek treatment.

The results underscore the importance of prevention and education efforts around cannabis use, especially among adolescents and young adults. Public health campaigns should emphasize the risks associated with cannabis, including impaired coordination, judgment, and the potential for injuries (7). Policymakers should consider these findings when crafting regulations and policies related to cannabis use, and future research should evaluate the overall burden of cannabis on the healthcare system (19). Furthermore, future research should examine the impact of cannabis legislation on injury incidence.

Our findings are not without limitations. While the NEISS data is a comprehensive and timely injury surveillance system to examine consumer product-related injuries, it does not capture injuries associated only with motor vehicle or motorcycles, therefore those injuries were not captured herein. Due to the NEISS sampling frame, the frequency of poisonings is under-represented, and trends in injury are potentially limited, as only ED visits were assessed. Drug use was based on retrospective chart review of ED visits in participating hospitals. Therefore, whether or not toxicology screens were conducted is dependent upon individual hospital policy and the situational environment. Cannabis consumption was identified by intake personnel. Therefore, it is not known how recently the person had consumed cannabis in relation to injury occurrence, nor the route of administration or potency of the drug. Intake staff were instructed to note only those patients for whom the ED record indicated that drugs contributed to the incident of the injury and to name the drug in the narrative. The limitation of this is potential underreporting of drug use. Since portions of the data were collected during the COVID-19 pandemic, ED visits may have been impacted in that some persons avoided or delayed treatment for medical issues (20), which may have decreased the number of visits for injuries. Lastly, a sensitivity analysis of cannabis use provided in the narrative reports was not possible.

Conclusions

In conclusion, our findings provide valuable insights into the concomitant use of cannabis and injuries, their impact on the health care system, and the impact on mechanisms of injuries other than motor vehicle crashes. Further research is necessary to understand the scope and association of cannabis use on injuries. As THC concentrations increase, mechanisms of administration evolve, and policies change, it will be important to maintain surveillance on outcomes associated with cannabis use.

Acknowledgments

Funding: None.

Footnote

Reporting Checklist: The authors have completed the STROBE reporting checklist. Available at https://jeccm.amegroups.com/article/view/10.21037/jeccm-24-37/rc

Peer Review File: Available at https://jeccm.amegroups.com/article/view/10.21037/jeccm-24-37/prf

Conflicts of Interest: Both authors have completed the ICMJE uniform disclosure form (available at https://jeccm.amegroups.com/article/view/10.21037/jeccm-24-37/coif). The authors have no conflicts of interest to declare.

Ethical Statement: The authors are accountable for all aspects of the work in ensuring that questions related to the accuracy or integrity of any part of the work are appropriately investigated and resolved. The study was conducted in accordance with the Declaration of Helsinki (as revised in 2013). The study was approved by The University of Arkansas Institutional Review Board (IRB registration No. 0018463) and individual consent for this retrospective analysis was waived.

Open Access Statement: This is an Open Access article distributed in accordance with the Creative Commons Attribution-NonCommercial-NoDerivs 4.0 International License (CC BY-NC-ND 4.0), which permits the non-commercial replication and distribution of the article with the strict proviso that no changes or edits are made and the original work is properly cited (including links to both the formal publication through the relevant DOI and the license). See: https://creativecommons.org/licenses/by-nc-nd/4.0/.

References

1. Hasin D, Walsh C. Trends over time in adult cannabis use: A review of recent findings. Curr Opin Psychol 2021;38:80-5. [Crossref] [PubMed]
2. Hasin DS, Shmulewitz D, Sarvet AL. Time trends in US cannabis use and cannabis use disorders overall and by sociodemographic subgroups: a narrative review and new findings. Am J Drug Alcohol Abuse 2019;45:623-43. [Crossref] [PubMed]
3. Substance Abuse and Mental Health Services Administration (SAMHSA). Key substance use and mental health indicators in the United States: results from the 2020 National Survey on Drug Use and Health. Rockville, MD: Center for Behavioral Health Statistics and Quality, Substance Abuse and Mental Health Services Administration; 2021. Available online: https://www.samhsa.gov/data/sites/default/files/reports/rpt35319/2020NSDUHFFR1PDFW102121.pdf
4. Meier MH, Caspi A, Ambler A, et al. Persistent cannabis users show neuropsychological decline from childhood to midlife. Proc Natl Acad Sci U S A 2012;109:E2657-64. [Crossref] [PubMed]
5. Arkell TR, Vinckenbosch F, Kevin RC, et al. Effect of Cannabidiol and Δ9-Tetrahydrocannabinol on Driving Performance: A Randomized Clinical Trial. JAMA 2020;324:2177-86. [Crossref] [PubMed]
6. Freeman TP, Craft S, Wilson J, et al. Changes in delta-9-tetrahydrocannabinol (THC) and cannabidiol (CBD) concentrations in cannabis over time: systematic review and meta-analysis. Addiction 2021;116:1000-10. [Crossref] [PubMed]
7. Hartman RL, Huestis MA. Cannabis effects on driving skills. Clin Chem 2013;59:478-92. [Crossref] [PubMed]
8. Li MC, Brady JE, DiMaggio CJ, et al. Marijuana use and motor vehicle crashes. Epidemiol Rev 2012;34:65-72. [Crossref] [PubMed]
9. Pearlson GD, Stevens MC, D'Souza DC. Cannabis and Driving. Front Psychiatry 2021;12:689444. [Crossref] [PubMed]
10. Rogeberg O, Elvik R. The effects of cannabis intoxication on motor vehicle collision revisited and revised. Addiction 2016;111:1348-59. [Crossref] [PubMed]
11. Kamer RS, Warshafsky S, Kamer GC. Change in Traffic Fatality Rates in the First 4 States to Legalize Recreational Marijuana. JAMA Intern Med 2020;180:1119-20. [Crossref] [PubMed]
12. Patrick ME, Fleming CB, Fairlie AM, et al. Cross-fading motives for simultaneous alcohol and marijuana use: Associations with young adults' use and consequences across days. Drug Alcohol Depend 2020;213:108077. [Crossref] [PubMed]
13. Biasutti WR, Leffers KSH, Callaghan RC. Systematic Review of Cannabis Use and Risk of Occupational Injury. Subst Use Misuse 2020;55:1733-45. [Crossref] [PubMed]
14. CPSC. Consumer Product Safety Commission. National Electronic Injury Surveillance System Sample Design and Implementation. 2019. Available online: https://www.cpsc.gov/s3fs-public/pdfs/blk_media_2001d011-6b6.pdf
15. CPSC. Consumer Product Safety Commission. National Electronic Injury Surveillance System Coding Manual 2022. Available online: https://www.cpsc.gov/s3fs-public/2019_NEISS_Coding_Manual.pdf
16. Thompson MC, Wheeler KK, Shi J, et al. An evaluation of comparability between NEISS and ICD-9-CM injury coding. PLoS One 2014;9:e92052. [Crossref] [PubMed]
17. National Cancer Institute. Joinpoint Trend Analysis Software 2023. Available online: https://surveillance.cancer.gov/joinpoint/
18. Brubacher JR, Chan H, Staples JA. Cannabis-impaired driving and Canadian youth. Paediatr Child Health 2020;25:S21-5. [Crossref] [PubMed]
19. Wilson J, Freeman TP, Mackie CJ. Effects of increasing cannabis potency on adolescent health. Lancet Child Adolesc Health 2019;3:121-8. [Crossref] [PubMed]
20. Czeisler MÉ, Marynak K, Clarke KEN, et al. Delay or Avoidance of Medical Care Because of COVID-19-Related Concerns - United States, June 2020. MMWR Morb Mortal Wkly Rep 2020;69:1250-7. [Crossref] [PubMed]