The effects of recreational cannabis legalization in Alberta on poison control centre calls and paediatric emergency department visits

Abstract

The growing body of research into the effects of recreational cannabis legalization on children in Canada is uncovering alarming trends. In the USA and Canada prior to legalization there have been gradual increases in hospital presentations and poison control centre calls over time for cannabis exposures in paediatric patients (1–3). In jurisdictions that have legalized cannabis, there have been contemporaneous sharp rises in these indicators of harm (3–6). Additionally, the legalization of the sale of edible cannabis formulations has been found to compound this problem (1,4,7,8), with a study by Cohen et al. showing an increase in paediatric intensive care unit (PICU) admissions immediately following the legalization of edible cannabis products in Ontario at a time when other recreational forms of cannabis were already legally available.

The potential harms of cannabis are often not fully understood by the public (9). Edible formulations of cannabis are especially enticing to young children as they often are baked into sweets or made to look like candies. Young children are at risk of overdoses which can result in loss of consciousness, hemodynamic instability, significant respiratory depression, and rarely death (10). In adolescents, regular use can lead to cannabis use disorder, cannabis hyperemesis syndrome, and impaired cognition, and is associated with an increased risk of schizophrenia and psychosis (11,12).

The present study aims to characterize cannabis-related emergency department (ED) presentations at the two major children’s hospitals in Alberta (the Stollery Children’s Hospital in Edmonton, and the Alberta Children’s Hospital in Calgary). As well, this is the first Canadian study to characterize calls concerning paediatric cannabis exposures to a poison control centre as they relate to legalization. This is a 4-year study period centred on the legalization of cannabis in Alberta (October 2016 to October 2020). Specifically, we aim to determine whether the frequency and/or severity of these presentations significantly increased following legalization, in keeping with the observations of researchers in other provinces and states.

METHODS

This retrospective, observational study consists of a medical record review of cannabis-related paediatric presentations to the Stollery Children’s Hospital (hereafter, the Stollery) ED in Edmonton and Alberta Children’s Hospital (ACH) ED in Calgary. To determine which presentations to the hospital were cannabis-related and pertinent to this study, records are filtered by their International Classification of Disease (ICD)-10 codes for discharge diagnoses and restricted to the relevant observational period. The included ICD-10 codes are categories ‘F12.*: Mental and behavioural disorders due to use of cannabinoids and ‘T40.7: Poisoning by cannabis (derivatives)’. All patients under the age of 18 presenting to either the Stollery or ACH are included. Charts are excluded if cannabis was not directly related to the presentation (e.g., a patient with a history of cannabis use that is not relevant to the presenting complaint).

From the included charts, patient demographics such as age, gender, comorbidities, and prior overdoses are collected by three non-blinded chart reviewers. To minimize interobserver variability, a data collection sheet was created prior to the review and unclear cases were discussed by the three chart reviewers. Additionally, symptoms at presentation, type of product and co-exposures, intentional versus unintentional exposures, interventions, hospital admissions, and disposition are retrieved. When possible, the route of exposure, type of exposure, and history of cannabis use are obtained from the visit documentation. Determining if cannabis was the primary reason for presentation, was based on discharge diagnosis and a judgement by the reviewers as to whether the patient might have presented had cannabis not been involved.

The severity of presentation is determined by grouping symptomatic and interventional indicators into severe and mild categories. Severe symptomatic indicators include autonomic changes or respiratory distress (apnea, bradycardia, hypothermia, respiratory depression, tachycardia, hypertension), altered level of consciousness/syncope, seizures, or psychiatric manifestations such as psychosis, hallucinations, or delusions. We focus on severe symptoms as these seemed most likely to indicate the need for significant intervention or potential adverse patient outcomes. Mild indicators include diaphoresis, vomiting, and mydriasis (see Supplementary Table 2 for all included symptoms). Significant interventions that indicate a more severe presentation include antiepileptic use, Intravenous (IV) fluids, vasoactive medications, oxygen, Computed Tomography (CT) head, intubation, consultation of paediatrics or PICU, and transfer from a peripheral hospital. Chart reviewers discussed cases frequently during the review process to ensure consistency in reporting. Secondary outcomes included an analysis of the severity of the presentation as compared to intentionality and the timing of legalization.

The Poison and Drug Information Services (PADIS) database (Tableau) is searched for all calls related to paediatric presentations for Cannabinoids and Analogues. This database categorizes some call subjects as ‘teens’ and ‘unknown child under 19’, so the search criteria are expanded to the age range 0 to 19 to capture all relevant calls. For PADIS, the primary metric examined is the volume of cannabis-related calls in the post-cannabis legalization period compared to the pre-legalization period. Calls in Tableau are able to be stratified by age (5 and under, 6 to 12, teen) and the type of cannabis product involved.

Study data were collected and managed using Research Electronic Data Capture (REDCap) electronic data capture tools hosted at the University of Alberta (13,14) REDCap is a secure, web-based software platform designed to support data capture for research studies, providing 1) an intuitive interface for validated data capture; 2) audit trails for tracking data manipulation and export procedures; 3) automated export procedures for seamless data downloads to common statistical packages; and 4) procedures for data integration and interoperability with external sources.

Statistical analyses for this project are performed by a statistician from the Women and Children’s Health Research Institute (WCHRI) using SAS Ver. 9.4 (SAS Institute Inc., Cary, NC, USA). Descriptive statistics are used for many of the variables studied, and the Exact test is used to determine the significance of differences between the pre- and post-legalization periods and accounts for any cell that contains frequency <5, with a P-value of <0.05 considered significant. To control for department volumes pre- and post-legalization, a test of difference is conducted utilizing baseline ED visit numbers over the study time period. For changes resulting in proportions greater than 1, the confidence interval could not be accurately determined and so was excluded from analysis (Tables 1 and 2). To analyze the relation of cannabis as the primary reason for presentation with the age of the patient and legalization of cannabis we utilize a multivariate logistic regression, beginning with univariate logistic regression analysis. Variables with P values less than 0.25 are included in the multivariate model, which is refined iteratively until the final model is established (Supplementary Table 5). Where data for variables is not included in the chart it is excluded from analysis.

This study and its methodology are ethically approved by both the University of Calgary and the University of Alberta following review by the institutional ethics boards.

RESULTS

Of 495,780 presentations to the two major paediatric EDs in the province during the examined time period, 1033 encounters had ICD-10 discharge diagnostic codes F12.* and T40.7 (Supplementary Table 1). Of these encounters, there were 631 where cannabis was found to be significant to the presentation (Supplementary Table 1) and were included in this study.

The age of patients presenting to ED for cannabis-related reasons followed a bimodal distribution (Supplementary Figure 1), but the majority are teenagers with a median age of 15. The youngest patient meeting the study criteria is 2 months of age. Slightly fewer than half (43.6%) of the patients presenting for cannabis-related concerns had pre-existing psychiatric diagnoses (Supplementary Table 2). When the route of exposure was known, most cases involved inhalation of cannabis products (Supplementary Table 2). In total, 151 of the total patients (23.9%) reported using cannabis daily or multiple times daily (Supplementary Table 2). There were 85 admissions (13%) to all admitting services (general paediatrics, intensive care, surgical services, and psychiatry) (Supplementary Table 2).

Intentional exposures accounted for 524 (84%), while 74 (12%) were unintentional (Supplementary Table 3). When comparing presenting symptoms between the intentional versus unintentional overdose groups, the intentional overdose groups had higher rates of agitation, anxiety, psychosis, and altercations (Supplementary Table 3). The unintentional group had more cases involving an altered level of consciousness, hypotonia, mydriasis, respiratory depression, and somnolence (Supplementary Table 3). A greater proportion (15% versus 2%) of unintentional overdoses required admission to the general paediatrics ward (Supplementary Table 4).

There were 309 encounters that occurred prior to legalization and 322 after legalization (Table 1). The total province-wide volume of ED presentations after legalization did not increase (Table 1). However, there was an increase in presentations in the younger cohort (under 11) in the post-legalization period from 7% to 15%, as well as an increase in unintentional overdoses from 7% to 17% (Table 1). A multivariate logistic regression analysis of cases pre- and post-legalization demonstrated that each additional year of age increase was associated with a 19.4% decrease in odds of presenting with cannabis as the primary reason (odds ratio 0.81, P < 0.001) (Supplementary Table 5). This modelling indicates that younger individuals are more likely to present with cannabis as the primary reason, and the likelihood of such presentations has increased following the legalization of cannabis in October 2018 (Table 1). We found an increase in cannabis ingestion after 2018 from 10% to 22% (Table 1). There was an increase in cases involving a diagnosis of cannabis hyperemesis syndrome, but total numbers for this variable were low 2% to 8% (Table 1). There were no indicators of increased severity, and there was no increase in admissions to the hospital (Table 1).

In the period covered by this study, there were no deaths associated with cannabis exposure. There were two intubations (0.003%) and two PICU admissions (0.003%) in our study population (although PICU was consulted for five cases (0.008%)). The most common service consulted was psychiatry (147 cases, 23%). Admissions to an inpatient paediatrics ward involved 23 (3.6%) patients (Supplementary Table 2).

The second component of our study was the analysis of calls to PADIS, of which there were 396 total calls during the study period for cannabis-related concerns (Table 3). Calls increased in all age groups, especially in those under 5 years old (Figure 1). This is despite an overall decrease in calls to PADIS over the study time frame (Table 3). The most common formulation of cannabis differed by age group for these calls -- for teenagers, it was most common for PADIS to receive calls about exposure to dried plants (127 calls, 68%) whereas for children 12 and under it was most commonly for edibles (Supplementary Table 6). The total number of calls related to exposure to cannabis edibles surpassed those for dried flower products during the study time period (Figure 2).

Figure 1.

Poison and Drug Information Services calls by age, pre- and post-legalization (total calls n = 396)

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Figure 2.

Number of calls to Poison and Drug Information Services by formulation and year

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DISCUSSION

The goal of our study was to determine whether there was a change in cannabis-related presentations in Alberta associated with the legalization of recreational cannabis. We found that the expected increase was not seen in terms of presentations for cannabis when including both intentional and unintentional exposures over the study period. It is possible that the lack of change during this short window was because the majority of our study population were older teenagers with intentional exposures. This portion of our study population had a heavy burden of co-morbid psychiatric diagnoses and cannabis overuse and addictions were a frequent reason for presentation. It is possible that there was no overall increase seen during our study period as these youth may have been at high risk for addictions prior to the legalization of recreational cannabis. We did see an increase in calls to PADIS for cannabis exposures which may reflect a widespread increase in general use across the province following legalization.

Our study has provided a detailed view of cannabis ingestions and overdoses in the province of Alberta encapsulating the legalization of cannabis products. While similar studies rely on administrative data (3,5,8), this study utilizes analyses of hospital charts to give a clear picture of the state of cannabis exposure in the province of Alberta. This adds to the existing evidence that legalization of recreational cannabis is strongly associated with an increase in ED visits, admissions to hospitals, and calls to poison control in young children (1–4,7,8). Interestingly, admissions to hospital were only 13% of our study cohort as compared to 32% seen in a similar Ontario-based study (6) possibly due to the fact that our study included intentional exposures and theirs had a greater percentage of edible cannabis exposures (76% versus 19%).

Likely owing to their similarity to conventional candies and desserts, many exposures in younger children are related to edible cannabis formulations (8,15). While this study did see an increase in exposure to edibles over the observation period, it only captured the first year after edibles were legalized in October 2019. Other studies have shown that the legalization of edible formulations of cannabis is strongly linked to increased presentations in this cohort (8). This study contributes to that knowledge since, in the short period around cannabis legalization in Alberta, the number of edible-related calls surpassed even those relating to dried cannabis. Edibles are associated with higher severity outcomes in young children (1,10) so this trend is a concerning one that warrants continued monitoring. The increases in calls to our poison control centre that we see in our study correspond with similar studies in the USA where legalization has occurred (2,16).

The paediatric population is a vulnerable one. The teenagers who represented the bulk of our study subjects have high rates of psychosocial stressors and mental health diagnoses. Many of them use cannabis daily or multiple times daily. The ED can be an important point of medical contact for these youth as a place to assist in arranging interventions and support. For these patients it may be useful to utilize a scoring tool such as the ‘CRAFFT’ substance abuse screening test to establish the severity of use, followed by connection with appropriate supports in the community and brief motivational interviewing with the team in the ED (17).

In this study, we have seen yet another strong correlation between the legalization of recreational cannabis—especially of edible formulations—and adverse outcomes for children. The results of this and similar studies show that we require stronger public messaging around the dangers of cannabis to young children.

LIMITATIONS

Our study was constrained by its retrospective nature, and by the fact that some information and presentations could have been erroneously excluded due to a reliance on discharge diagnoses and ED documentation. Our numbers may provide a conservative estimate of exposures to cannabis as many cases may go unreported or undocumented. PADIS calls were not limited to non-ED patients, so there could have been an element of double counting between our two methods of determining changes in cannabis cases. This study period involved the earliest years of legalization, and therefore the long-term impacts of legalization in Alberta, the legalization of edible formulations, and the impacts of the coronavirus disease 2019 pandemic on cannabis use in adolescents were not assessed and would be excellent topics for further research.

ACKNOWLEDGEMENT

We would like to thank the Women and Children’s Health Research Institute (WCHRI) for their support and funding for this project.

FUNDING

No funding to report.

POTENTIAL CONFLICT OF INTEREST

All authors: No reported conflicts of interest. All authors have submitted the ICMJE Form for Disclosure of Potential Conflicts of Interest. Conflicts that the editors consider relevant to the content of the manuscript have been disclosed.

REFERENCES