198 Neuropsychiatric Effects of Cannabis Toxicity in the Emergency Department: A Community-Based Study

Abstract

The state law to legalize recreational use of marijuana in Michigan went into effect in December 2018. Increased availability and use of cannabis in Michigan have led to a marked increase in emergency department (ED) visits associated with the drug’s neuropsychiatric effects. Our purpose was to describe the prevalence, clinical features, and disposition of cannabis neuropsychiatric toxicity in a community-based study. This was a retrospective cohort analysis of consecutive patients diagnosed with toxicity related to cannabis use. Patients were seen at seven emergency departments (EDs) over a 24-month study period (November 2018-October 2020). Spanning 13 counties in Michigan, affiliated institutions included three rural medical centers, three university-affiliated hospitals, and a children’s tertiary care facility. Data collected included demographics, clinical features, and treatment outcomes in patients presenting to the ED with neuropsychiatric symptoms (NPS) versus those experiencing other forms of cannabis toxicity. Chi-squared and t-tests were used to compare these two groups across key demographic and outcome variables. One investigator performed a blinded critical review of a random sample of 10% of the charts to determine inter- rater reliability using kappa statistics. During the study period, 1214 patients were evaluated for cannabis toxicity. A total of 584 patients (48.1%) had a neuropsychiatric chief complaint (NPS group) and 630 (51.9%) experienced other forms of cannabis toxicity, predominantly symptoms of intoxication (51.0%) or cannabis hyperemesis syndrome (37.5%). The NPS group presented with acute anxiety (37.5%), suicidal ideation (18.4%), depression (16.1%), hallucinations (9.5%), mania (5.9%), seizures (5.5%), psychosis (4.6%), and paranoia (4.5%). NPS patients were more likely to younger (25.3 vs 29.2 years, P<0.001), have comorbidities (15.3 vs 9.2%, P=0.001) and a history of polysubstance abuse (13.2 vs 8.6%, P=0.004). These patients also had a longer ED length-of-stay (7.3 vs 4.0 hours, P<0.001) and significantly more hospital admissions (41.9% vs 6.4%, P<0.001). Reliability of data collection (k = 0.91) showed excellent agreement. Neuropsychiatric toxicity is common after acute or chronic cannabis exposures, occurring in nearly half of ED patients in this community-based study. These troublesome findings highlight the risks associated with the use of cannabis for recreational or therapeutic purposes.