Misuse and abuse of illicit drugs have increased worldwide, and consequently so has the risk of trauma-related injuries [11, 29–31]. Multiple studies have focused on the effects of marijuana and cocaine on trauma patients [5, 6, 11, 20, 24, 30]. However, when analyzing the effects on patient outcomes, they have failed to reach a consensus. This study evaluated the association between the toxicology testing status of patients admitted to the PRTH and the demographic profile, injury-related and hospital course factors, and outcomes of the trauma patients.

Our analysis of the trends of admission rates for toxicology-positive patients during 2002–2018 demonstrated a significant increase in the number of patients testing positive for marijuana, and marijuana and cocaine. Meanwhile, the number of patients testing positive for cocaine did not show any statistically significant change. These results are consistent with the recent increase in marijuana use in the US population reported by the National Institute on Drug Abuse (NIDA) along with previous studies [25, 32, 33]. However, NIDA also reported a diminution of cocaine use since 2007, which is not seen in our admissions trends [32].

In the US, marijuana use is most prevalent among the 18–25 age range, while cocaine is most prevalent among the 26 or older age range [4]. Our results show a similar distribution with patients testing positive for marijuana predominantly being in the 18–24 age group, and patients testing positive for cocaine primarily being in the 35–44 group. These results were compared to the drug use statistics of the US mainland since there was a lack of statistics on adult marijuana and cocaine use in PR. Additionally, our analysis shows that the patients who tested positive for both marijuana and cocaine were mainly in the 25–34 age group. This age group is located between the most prevalent age groups of marijuana positive and cocaine positive patients.

Our analysis suggested that the use of marijuana and cocaine, independently and in conjunction, is linked to interpersonal violence (i.e., gunshot wounds, stab wounds). On the other hand, a negative toxicology test was associated with non-violent mechanisms of injury (i.e., motor vehicle accidents). These findings are in agreement with previous studies, which links marijuana and cocaine to violent injury mechanisms of trauma [8, 9, 30, 34]. Additionally, recent literature on the topic has found an increase in marijuana positive toxicology results among patients in motor vehicle accidents [12, 13]. Our results seem to confirm this trend since motor vehicle accidents were the second most common mechanism of injury for patients who tested positive to marijuana.

In terms of the patients’ clinical profile, the ISS varied depending on the toxicology test result. Patients with a positive toxicology test had higher relative frequencies of an ISS ≥ 25. These results are in agreement with a previous study from Spain, which reported that the pre-injury consumption of drugs increases the likelihood of more severe injuries [19]. However, another study did show that cocaine positive patients had a lower ISS than negative patients [26]. Perhaps these observed results are related to the difference in the mechanisms of injury of patients with a positive toxicology and those with a negative toxicology. As previously mentioned, our study found a link between a positive toxicology and violence related mechanisms of injury, like gunshot wounds and stab wounds, which constitute penetrating injuries. Meanwhile, our data showed that a negative toxicology was associated with non-violent mechanisms of injury, like motor vehicle accidents, which tend to cause non-penetrating injuries.

Our study showed that surgery was required significantly more often for patients in all three positive groups when compared to patients in the negative group. A previous study on marijuana positive patients found an increase in the number of surgeries required, when compared to negative patients [27]. Meanwhile, a study on cocaine positive patients found no change in the need for surgery, when compared to patients testing negative [28]. Unfortunately, we were not able to find previous studies that focused on patients testing positive for both marijuana and cocaine simultaneously for comparison.

Furthermore, our analysis revealed that admissions to the TICU were not associated with toxicology results. Previous studies on the matter showed conflicting evidence. One reported similar results to ours in patients testing positive to cocaine [20], while another one pointed out to an increase in TICU admissions for cocaine or marijuana positive patients [28]. We also found that the need for MV was not linked to toxicology results. Preceding research had found that patients with a positive toxicology result required MV more often than patients testing negative [6, 21, 35]. Regarding the total amount of days receiving MV, previous research showed no differences between marijuana positive and negative testing patients [24]. These results were also seen in our data, nevertheless we also found that the cocaine positive group spent more days on MV than patients in the marijuana positive and negative groups.

When analyzing the study endpoints, the type of trauma modified the effect of toxicology status on complications, TICU LOS, and hospital LOS. We found that, among non-penetrating trauma patients, a positive toxicology for marijuana or cocaine was related to an increased adjusted risk of complications, longer TICU LOS, and longer hospital LOS; while in penetrating trauma patients no significant associations were found. To our knowledge these particular findings have not been reported in previous studies, which emphasizes the need for further research into how the mechanisms of injury affect the outcomes of patients who test positive for these drugs.

The published literature has examined these outcomes without considering interactions with the type of trauma, and most of the studies have used bivariate statistical techniques (an approach that does not account for confounding factors). One of the widest studied parameters is the hospital LOS, which has yielded inconsistent results. Some works showed no difference in hospital LOS for marijuana or cocaine positive patients when compared to negative testing patients [22–24, 26, 28]. Meanwhile, other analyses did find that patients with positive toxicology had longer hospital LOS than negative patients [20, 25, 27].

There is still conflicting evidence on the effects of drugs on mortality rates of trauma patients. For example, in marijuana positive patients, one study showed lower mortality rates [6], another reported an increase in mortality rates [19], and others found no association between marijuana and the risk of in-hospital mortality rates in trauma patients [20–23]. In cocaine patients, the majority of studies have found no association between having a cocaine positive result and the risk of in-hospital mortality [20, 22, 26, 28]. However, there was one study that did find an increase in mortality rates for patients with a positive toxicology test [19]. Nevertheless, after adjusting for confounders, our results showed no significant difference in the in-hospital mortality rate for the different groups, meaning that we found no association between a positive toxicology result and a change in the mortality rates of our patients.

The use of marijuana and cocaine both independently and in conjunction has direct effects on a person’s physiology, psychology, and behavior [8, 9]. While the psychological effects of marijuana vary from person to person, these effects may include paranoia, delusions, and hallucinations [36–38]. Meanwhile, cocaine’s effects can also include panic and paranoia, as well as euphoria and irritability [39–41]. These effects can all lead to erratic and violent behaviors, which can all translate to traumatic injuries. Therefore, as illicit drug use continues to increase, it is extremely important to understand the trends shown by these patients. This explains the relevance of our results, along with the need for further studies on this topic, in order to reach a consensus on the effects these drugs have on trauma patients. This will lead to a better understanding of their condition, which will allow for the development of intervention strategies that improve their outcomes. Additionally, trauma is a preventable disease, which means that strategies can also be established to promote the safety of marijuana and cocaine users.

Due to its retrospective nature, our study has some limitations. First, it did not allow us to analyze some confounding variables (e.g., time of drug consumption, amount of drug consumed, among others) that could have impacted the effects the drugs had on the patients. Additionally, due to the half-life of the metabolites used to measure marijuana and cocaine use, there is sometimes a challenge in detecting the presence of these drugs. Therefore, there is a possibility that some patients with a negative toxicology result could have had these drugs present in their bodies during the injury. Furthermore, our study did not focus on the specific physiological effects of the consumption of marijuana and cocaine that could have impacted the outcomes of patients. Also, our study did not focus on the difference between sporadic recreational and constant medical use of marijuana in these patients, which could also be important in explaining our results. Besides, most of the data collected for the study was obtained before the legalization of medical marijuana use in PR. Hence, we were not able to examine for any post-legalization exclusive changes in the trends and outcomes of these patients. Lastly, the data collected was limited to a local population in a single institution, which means that our results cannot necessarily be extrapolated to other populations. However, the PRTH is the only trauma specialized hospital on the island. In addition, since alcohol tests were not included in our data set, we were not able to address this variable in our study. Despite these limitations, this study is one of the first to evaluate drug use in trauma patients in PR, and one of the first to include patients who use marijuana and cocaine simultaneously, providing the precedent for future studies, which might also explore interactions between marijuana and cocaine and other drugs.

In summary, our study revealed an association between a positive toxicology test in trauma patients and a higher need for surgery. Additionally, we found that a positive toxicology for marijuana or cocaine was linked to an increased adjusted risk of complications, longer TICU LOS, and longer hospital LOS in non-penetrating trauma patients. These findings suggest that patients with positive toxicology results, particularly those with non-penetrating trauma, might benefit from more aggressive management. However, there still exist conflicting results regarding this topic, and for this reason, we recommend more in-depth research on how the physiology of trauma patients is affected by these drugs. This will help reach a consensus on the topic, which is essential to identify the most effective treatments for patients that have a positive toxicology test.