Medicinal Cannabis Prescription Before an Inpatient Psychiatric Admission: A Retrospective Observational Audit

BACKGROUND: Prescribing of medicinal cannabis has expanded in Australia; however, evidence for benefit in psychiatric populations is limited. The goal of this study was to estimate the prevalence and characteristics of recent medicinal cannabis prescribing among psychiatric inpatients and to describe presentations associated with these admissions. METHODS: We conducted a retrospective observational audit of adult patients admitted to a large metropolitan adult acute psychiatric unit in Brisbane, Australia, between September 2021 and October 2023. Electronic medical records were reviewed to identify medicinal cannabis prescriptions in the 90 days before admission. Information concerning demographics, indications, formulation, labeled potency, dispensing frequency, presentations, and length of stay were extracted for patients who had received such prescriptions. RESULTS: Of the 752 patients who were screened, 35 patients (4.7%) were prescribed medicinal cannabis in the 90 days before admission. Most of the patients (91.4%) who had been prescribed medicinal cannabis had a prior psychiatric diagnosis. The leading indication for the prescribed medicinal cannabis was anxiety (48.6%). Nearly all of the patients who were prescribed medicinal cannabis (97.1%) were prescribed at least one product containing delta-9-tetrahydrocannabinol (THC), with a mean THC concentration of 24%. The majority of patients prescribed medicinal cannabis (88.6%) were admitted with psychosis. CONCLUSION: A small but clinically important proportion of psychiatric inpatients vulnerable to psychosis had recent prescriptions for medicinal cannabis, predominantly for higher-potency THC-containing products. Product type, labeled potency, and timing of the last dispensing should be documented in routine psychiatric assessment. Further work clarifying the risks and benefits of cannabis prescribing in this population is required.