Alternatively, being male, having elevated blood alcohol levels and having other drugs present on admission were all found to have a significant influence on GCS scores and TBI severity, with GCS scores being lower for all three variables, implying a more serious TBI. Similarly, having a diagnosis of cancer, mental or personality disorder and alcohol use disorder were found to have an influence on GCS scores. Participants with a diagnosis of cancer or mental/personality disorder were found to have lower GCS scores, again, implying a more serious TBI. Conversely, participants with a diagnosis or history of alcohol use disorder had higher GCS scores, indicating a less serious TBI. While the presence of THC initially did show a hypothesized relationship to GCS score , the relationship became insignificant when adjusted for all the other covariates variables. Because of the large percentage of missing data, the validity of findings, such as THC prevalence rate in this TBI population, should be cautiously interpreted for all the included hypothesized explanatory variables. Further research with datasets that are larger and more complete are needed to fully understand and examine the relationship between marijuana and TBI severity. This study importantly underscores the need for better data to enable better research regarding the relationship between marijuana and TBI severity. Traumatic brain injury is a significant public health concern as it is a leading cause of mortality, morbidity and disability in the United States . According to the World Health Organization, TBI is expected to become the third leading cause of death and disability in the world by 2020. In the United States TBI contributes to a third of all injury related deaths . A traumatic brain injury,grow trays as defined by the Centers for Disease Control and Prevention , is a disturbance of the brain’s normal function that occurs when an individual sustains a blow, jolt, or bump to the head, or sustains a penetrating head injury .
Traumatic brain injuries can lead to a variety of secondary conditions that could result in cognitive, behavioral, motor, and somatic impairments that cause long-term disability and poor quality of life . The leading causes of injuries resulting in TBI prevalence are traffic related, such as motor vehicle crashes, or non-traffic related, such as falls. Falls are the leading cause of TBI with almost 81% of emergency department room visits in adults over the age of 65 attributed to falls . Motor vehicle collisions are the leading cause of TBI related deaths, with rates being highest for adults between the ages of 15-24, 25-35 and older adults greater than 75 . Notably, up to 51% of all TBI patients have substance use exposure at the time of injury . Substance use includes alcohol and drugs such as marijuana. Current existing research suggest that in general, substance-exposed patients may have worse TBI outcomes, including greater rates of mortality and severity of injury. Research has also shown that these patients suffer worse functional outcomes, which can result in socioeconomic burden to patients and the nation at large. This healthcare burden has been calculated to be approximately $76.5 billion in 2010 alone . There is a substantial body of research elucidating the influence of alcohol on TBI prevalence and outcomes . Alcohol use results in impairments such as diminished motor control, blurred vision, and poor decision making, which in turn has been shown to increase the risk for TBI . This research has been used to create public health policies, public education efforts, and prevention programs that have made a significant health impact, such as reducing the number of alcohol-impaired drivers . While it is known that there is significant alcohol use related to TBI, little is known about the influence of marijuana on the prevalence, severity and outcomes related to TBI . Marijuana is an drug that despite being federally and legally regulated, remains the most widely used drug in the U.S. . Marijuana use has been shown to result in similar cognitive impairments as alcohol use, such as lack of coordination, alterations in reaction time, inability to pay attention, and decision-making abilities, suggesting marijuana users are similarly at increased risk for TBI .
There is some indirect evidence of this, in that it has been shown that marijuana users in general are about 25% more likely to be involved in a motor vehicle collision and that the older adult marijuana users have a greater risk for falls . Both short and long-term marijuana exposure has been shown to impair driving ability; marijuana is the drug most often reported in association with impaired motor vehicle collisions, including fatal ones . It has also been shown that the overall risk of being involved in a motor vehicle collision increases by a factor of 2 soon after an individual has used marijuana . Motor vehicle collisions make up almost two thirds of U.S. trauma center admissions and are the leading cause of TBI related deaths . Approximately 60% of MVC patients tested positive for drugs and alcohol . Despite the increase in marijuana use and exposure, concrete data linking marijuana exposure at time of injury and TBI prevalence and severity is scarce . Adding to the concern, national surveys on drug use and health have documented an increase in individual daily marijuana use over the last 5 years. In summary, there is no body of research documenting the relationship between marijuana exposure and TBI prevalence and severity. As the number of states legalizing marijuana for both medical and recreational use increases, it is imperative to resolve the ambiguity within the research available regarding the influence of marijuana exposure on TBI. This study will fill important gaps in knowledge about this emerging public health concern by documenting the prevalence of marijuana exposure in a national sample of TBI patients, and determine the relationship between marijuana exposure, mechanism of injury, and TBI severity. Study aims are to: 1) assess the prevalence of marijuana exposure in patients with moderate or severe TBI at time of injury; 2) examine correlates associated with marijuana exposure at the time of injury; and 3) examine the relationship between marijuana exposure, mechanism of injury and TBI severity. Results will provide the first quantifiable national-level evidence of the impact of marijuana exposure on TBI.
Results will also serve as the basis for research that can inform policy and public safety standards and metrics regarding marijuana exposure and its effect on TBI.A search strategy was implemented by searching the PUBMED electronic bibliographic database between January 17-19 in 2019. No restrictions were applied on publication status and publication date. This systematic review adhered to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses statement. The search strategy included the terms traumatic brain injury, severity, substance, substance abuse, marijuana, THC, cannabis, and drug use. Only publications in English were sought. Reference lists of review papers were searched to ensure all relevant literature was included. An example of the search strategy for this review is shown in Figure 1. To be included in this systematic review, studies must have been peer-reviewed, published in English, involve human subjects only, and must have investigated the use of marijuana in adult patients reported to have sustained a moderate to severe TBI. We did not consider participants below the age of 16 because pediatric trauma patients present differently than do adults,drying marijuana and are treated with different intervention protocols than in adults. A preliminary search identified the fact that articles subsumed marijuana exposure under the broader umbrella term of substance use/abuse. Therefore, substance and substance abuse terms were included to ensure a wide sensitivity to studies involving drugs such as marijuana. Exclusion criteria Patients with a diagnosis of mild TBI were excluded because up to 40% of mild TBI patients do not seek medical attention, and therefore, findings would not be representative . Similarly, the following studies were excluded from this review: studies that did not assess for marijuana exposure at time of injury, marijuana post-TBI, cellular based studies, clinical review papers, editorials, case reports, pediatric studies and studies using nonhuman subjects. Selection Process Study selection was conducted in a two-stage process. First, studies were screened by titles and abstracts for potential inclusion. Next, studies identified as relevant for potential inclusion underwent a full-text evaluation. Studies that included any information about marijuana exposure at the time of injury were included, including studies where marijuana was bundled with other substances as either a variable or via analysis, because it was assumed there would still be relevant information embedded within the study. The studies were reviewed a second time to ensure all inclusion criteria were met and included if they did.Data was extracted from studies that met selection criteria. Data from the studies were used to achieve the primary aims of this systematic review: to examine marijuana exposure and use in TBI prevalence, severity and outcomes.
The following data were abstracted to summarize specific study features and address the review’s aims: 1) study characteristics, including authors names, publication year, country, design, sample size, and methods utilized, 2) participant characteristics such as mean age and type of TBI, 3) information about whether other substances besides marijuana, such as alcohol, methamphetamines, cocaine, opiates, benzodiazepines, narcotics, stimulants, speed, hallucinogens and heroin were documented and/or analyzed 4) results, including the prevalence of marijuana, TBI outcomes, and if a relationship between marijuana and TBI was present.Search results, including abstracts and full-text articles, were exported to an Excel file for data management. The decision for inclusion or exclusion in the review process was recorded in the Excel file, as well as a rationale for exclusion of studies. Reference management was done through the Papers©, a reference management software used to manage bibliographies and references. A reference library of PDF documents was maintained through the software and allows a variety of features such as collecting, curating, merging of studies as well as the insertion of citations in-text. The Levels of Evidence were assessed using the National Heart, Lung and Blood Institute categories. The NHLBI Levels of Evidence framework rates evidence on four major levels, placing the highest rating on evidence that is acquired from Randomized Controlled Trials with an extensive body of data; RCTs are assigned a level “A” according to the NHLBI. Level B studies are RCTs with a limited body of data, usually involving a smaller sample size, include a subgroup analysis of RCTs, and may include study results that are inconsistent. Level C studies are those that employ a non-randomized study design, such as observational studies. Finally, Level D studies include studies that utilized mechanism-based reasoning that involve anecdotal findings based on expert opinion. Risk of bias of included articles was assessed using the National Heart, Lung and Blood Institute quality assessment tool for observational cohort and cross-sectional studies. The NHLBI offers six various study quality assessment tools, three of which apply to observational cohort studies, cross-sectional studies, and case series studies. The quality assessment of observational cohort and cross-sectional studies tool was utilized. The NHLBI quality assessment tool is comprised of 14 criteria/questions that address study objectives, study population, sample size, exposures and outcome measures, and key potential confounding variables. An example of NHLBI quality assessment tool for observational cohort and cross-sectional studies is presented in Table 2. Potential sources of bias were rated as either “yes”, “no”, “cannot determine”, “not applicable”, or “not reported”. Each study was given an overall bias rating of good, fair, or poor. Table 2 delineates responses to each of the 14 questions in the NHLBI quality assessment tool, while Table 3 addresses the types of biases encountered, the presence or lack thereof of confounding variables, and other information that aid in the assessment of biases.Results from the included studies were reviewed for the outcome of interest and were reported under seven themes: presence of marijuana exposure; time frame in which marijuana exposure was measured; method used to measure marijuana exposure; information on other substances if they were bundled with marijuana exposure; and the presence of a specific link between marijuana exposure and TBI severity. Due to the range and diversity of study results and designs, a meta-analysis was not possible. Additionally, given the differences in the conceptualization and definition of marijuana exposure across the studies included, and the heterogeneity in methods, sample data, collection and findings, a narrative interpretation and descriptive analysis of the findings was necessary.