How we gauge the impact of recreational and medical cannabis use presenting in the ED may benefit from a bit of re-thinking. High workload demands, a need to address the most immediate health concern and implicit bias may all be playing a role in the quality of the data that is used for much of the research in this field. A recent study in the ED for example examined rates of mistriage and found that roughly 30% of encounters were mistriaged across over 5 million encounters in the United States with groups such as Black Americans more likely to be mistriaged suggesting bias may play a role in the mistriage rates (56). There is a body of literature examining bias in healthcare delivery, with healthcare bias usually being reflected in poorer quality mental healthcare. Individuals with mental illness and addictions experience lower quality of care overall, with these diagnoses identified as a key factor in these negative outcomes (57). There are also studies showing health professionals have an implicit stigma against individuals with mental illness that can lead to poor outcomes for these patients (57–59). However, there is more than one type of stigma and some work has shown that implicit bias predicted over-diagnosis in individuals with mental health training and explicit bias predicted more negative outcomes for patients compared to providers with less mental health experience (60). Bias has been studied in ED personnel primarily with a socioeconomic lens (61). The ED is an environment that is high stress and highly physically demanding at times. While studies that focus on quality of care have examined possible errors to clinical practice with exhaustion in the ED environment, there is also a component of emotional exhaustion which can affect executive function and potentially allow a greater influence of personal bias as a result (62). There may also be, as noted by another group, biases in assigning cannabis use codes to certain racial and ethnic groups which might be related to the frequency of cannabis attributable visits (15). All of this discussion leaves aside the complication that not every patient will report cannabis use in the Emergency possibly due to stigma and given the long half-life of THC in the body, toxicological tests are not always informative. Combined, these factors suggest an examination of the impact of potential bias on ED encounters is required, particularly as it relates to cannabis associated physical and mental health ED presentations.

Further evidence that we may not be accurately tracking use of cannabis in the Emergency Department can be made by inference from the fatality information seen in motor vehicle collisions. The percentage of fatally injured drivers in the United States that had cannabis in their system in 2000 was 9.0%, but by 2018 it had risen to 21.8% in comparison to alcohol involvement which had remained stable (63). Additionally, when trauma patients were assessed, one study found 43% of these patients in 2016 had at least cannabis in their system and that injuries associated with the presence of cannabis were more likely to require mechanical ventilation (16). Another study done in Georgia showed that the odds of dying with cannabis were greater than those of cocaine if presentation to the ED was required (64). This information logically implies that cannabis use is more widely associated with trauma and fatalities and ED presentations than our current ICD code-based studies would suggest.

ED clinicians logically enter the codes for the trauma or symptoms to be urgently dealt with and entering a note on the role of cannabis may not be a priority in that moment. Additionally, the ED is commonly a very busy hospital unit and if triage codes are subject to error then by extension one might consider how accurate ICD code entry may be (56) Further not every clinical case in the ED is simple. For example, the situation with mental health presentations can complicated by an initial uncertainty of whether an anxiety presentation is a reflection of an acute adverse event or a longer standing diagnosis. However, if a drug–drug interaction between cannabis and a psychiatric medication has reduced the effectiveness of that psychiatric medications and this is the underlying cause of the ED presentation, how do we code this case? Many studies being done in the realm of the ED are subject to these complications but these weaknesses and how to address them to improve the accuracy of our findings are rarely discussed. This is why we suggest the new approach that groups such as (18) and our own group are taking of both using ICD codes and searching the electronic medical record are so important (18). Interestingly, Shelton found that ICD codes related to cannabis use were not necessarily attributed to cannabis use whereas our work suggests that the ICD codes are missing the cannabis association and merely representing the symptomatic presentation. These approaches demonstrate the weakness of a strictly administrative code approach for considering the role of substance use such as cannabis in ED visits but also may suggest differences in culture between American and Canadian Emergency Departments. In either case, the wider adoption of electronic charting, and technology to allow searching within these charts, will improve access to visit notes and hopefully add depth to findings in this field.