Development of an anxiety disorder following an emergency department visit due to cannabis use: a population-based cohort study.

Background: There is ongoing uncertainty about whether cannabis use increases the risk of developing an anxiety disorder. In this study we estimated the risk of having an incident healthcare visit for an anxiety disorder following an emergency department (ED) visit for cannabis use and explored factors associated with increased risk. Methods: We used health administrative data to perform a population-based cohort study of all individuals aged 10-105 years with no previous healthcare visits for anxiety disorders in Ontario, Canada, between January 2008 and March 2019. We compared the risk of having an incident healthcare visit for an anxiety disorder in the ED or hospital (primary analysis) or additionally in an outpatient setting (secondary analysis) for individuals with an incident ED visit for cannabis to members of the general population using cumulative incidence functions and cause-specific hazard models adjusted for relevant confounders. Findings: Our study included 12,099,144 individuals aged 10-105 without prior care for an anxiety disorder in the ED or hospital, of which 34,822 (0.29%) had an incident ED visit due to cannabis. Within 3-years of an incident ED visit due to cannabis, 12.3% (n = 4294) of individuals had an incident ED visit or hospitalization for an anxiety disorder-a 3.7-fold (adjusted Hazard Ratio [aHR] 3.69 95% CI 3.57-3.82) increased risk relative to the general population (1.2%). In secondary analysis, further excluding individuals with prior outpatient care for anxiety disorders, 23.6% of individuals with an ED visit due to cannabis had an incident outpatient visit, ED visit, or hospitalization for an anxiety disorder within 3-years compared to 5.6% of individuals in the general population (aHR 3.88 95% CI 3.77-2.99). The risk of having an incident healthcare visit for an anxiety disorder was higher in individuals with ED visits for cannabis use compared to the general population across all age and sex strata. However, younger males with ED visits for cannabis use (aHR 5.67 95% CI 5.19-6.21) had a greater risk relative to the general population than younger women with cannabis use (aHR 3.22 95% CI 2.95-3.52). Interpretation: ED visits for cannabis use were associated with an increased risk of having an incident healthcare visit for an anxiety disorder, particularly in young males. These findings have important clinical and policy implications given the increasing use of cannabis over time and trend towards legalization of cannabis. Funding: Canadian Institutes for Health Research.

Mortality in adolescents and young adults following a first presentation to the emergency department for alcohol.

BACKGROUND AND METHODS: We conducted a population-based, retrospective cohort study of first-time emergency department (ED) visits in adolescents and young adults (AYA) due to alcohol and compared mortality to AYA with nonalcohol ED visits between 2009 and 2015 using standardized all-cause mortality ratios (age, sex, income, and rurality). We described the cause of death for AYA and examined the association between clinical factors and mortality rates in the alcohol cohort using proportional hazard models. RESULTS: A total of 71,776 AYA had a first-time ED visit due to alcohol (56.1% male, mean age 20.7 years) between 2009 and 2015, representing 3.3% of the 2,166,838 AYA with an ED visit in this time period. At 1 year, there were 2396 deaths, 248 (10.3%) following an ED visit related to alcohol. First-time alcohol ED visits were associated with a threefold higher risk in mortality at 1 year (0.35% vs. 0.10%, adjusted hazard ratio [aHR] 3.07, 95% confidence interval [CI] 2.69-3.51). Mortality was associated with age 25-29 years (aHR 3.88, 95% CI 2.56-5.86), being male (aHR 1.98, 95% CI 1.49-2.62), having a history of mental health or substance use (aHR 3.22, 95% CI 1.64-6.32), cause of visit being withdrawal/dependence (aHR 2.81, 95% CI 1.96-4.02), and having recurrent ED visits (aHR 1.97, 95% CI 1.27-3.05). Trauma (42.7%), followed by poisonings from drugs other than opioids (38.3%), and alcohol (28.6%) were the most common contributing causes of death. CONCLUSION: Incident ED visits due to alcohol in AYA are associated with a high risk of 1-year mortality, especially in young adults, those with concurrent mental health or substance use disorders, and those with a more severe initial presentation. These findings may help inform the need and urgency for follow-up care in this population.

Transition to Schizophrenia Spectrum Disorder Following Emergency Department Visits Due to Substance Use With and Without Psychosis.

Importance: Episodes of substance-induced psychosis are associated with increased risk of developing a schizophrenia spectrum disorder. However, there are limited data on the transition risk for substance use without psychosis. Objectives: To quantify the risk of transition to schizophrenia spectrum disorder following an incident emergency department (ED) visit for (1) substance-induced psychosis and (2) substance use without psychosis and to explore factors associated with transition. Design, Settings, and Participants: A population-based retrospective cohort study (January 2008 to March 2022) of all individuals, aged 14 to 65 years, in Ontario, Canada, with no history of a psychotic disorder. Individuals with incident ED visits for substance use with and without psychosis were compared with members of the general population. Main Outcomes and Measures: Transition to schizophrenia spectrum disorder using a chart-validated algorithm. Associations between ED visits for substance use and subsequent transition were estimated using cause-specific hazard models. Results: The study included 9 844 497 individuals, aged 14 to 65 years (mean [SD] age, 40.2 [14.7] years; 50.2% female) without a history of psychosis. There were 407 737 individuals with an incident ED visit for substance use, of which 13 784 (3.4%) ED visits were for substance-induced psychosis. Individuals with substance-induced psychosis were at a 163-fold (age- and sex-adjusted hazard ratio [aHR], 163.2; 95% CI, 156.1-170.5) increased risk of transitioning, relative to the general population (3-year risk, 18.5% vs 0.1%). Individuals with an ED visit for substance use without psychosis had a lower relative risk of transitioning (aHR, 9.8; 95% CI, 9.5-10.2; 3-year risk, 1.4%), but incurred more than 3 times the absolute number of transitions (9969 vs 3029). Cannabis use had the highest transition risk among visits with psychosis (aHR, 241.6; 95% CI, 225.5-258.9) and the third-highest risk among visits without psychosis (aHR, 14.3; 95% CI, 13.5-15.2). Younger age and male sex were associated with a higher risk of transition, and the risk of male sex was greater in younger compared with older individuals, particularly for cannabis use. Conclusions and Relevance: The findings of this cohort study suggest that ED visits for substance use were associated with an increased risk of developing a schizophrenia spectrum disorder. Although substance-induced psychoses had a greater relative transition risk, substance use without psychosis was far more prevalent and resulted in a greater absolute number of transitions. Several factors were associated with higher transition risk, with implications for counseling and early intervention.