Persistence of use of prescribed cannabinoid medicines in Manitoba, Canada: a population-based cohort study.

Abstract

To estimate prevalence of continuous use (persistence) of prescribed cannabinoid medications for up to 1year from initial prescription in Manitoba, Canada and predictors of duration of use. A retrospective, population-based, cohort study using administrative data from the Manitoba Population Research Data Repository located at the Manitoba Centre for Health Policy, Canada. People without a record of a previous prescription who were prescribed a cannabinoid medication from 1 April 2004 to 1April 2016 followed for 1year from the date of first prescription. Continuous prescribed cannabinoid medication use was defined as use without a gap exceeding 60days between prescriptions. The primary outcome was prevalence of continuous prescribed cannabinoid medication use for up to 1year. A secondary outcome was duration of continuous use. Predictors were socio-demographic characteristics, medical diagnoses and type of cannabinoid medication. Among 5452 new users, 18.1% [95% confidence interval (CI)=17.08-19.12] were still using cannabinoids at 1year. Median duration of use was 31days [interquartile range (IQR)=25-193]. This was highest for nabilone (33days, IQR=25-199) and lowest for nabiximols (20days, IQR=7-30). Use was longest among 19-45- and 46-64-year-old users and those with the highest socio-economic status. Fibromyalgia [hazard ratio (HR)=0.89, 95% CI=0.84-0.95], osteoarthritis (HR=0.91, 95% CI=0.82-0.97) and substance use disorder (HR=0.85, 95% CI=0.76-0.94) diagnoses were associated with longer use (HR for discontinuation-HR<1 less discontinuation and longer use). A diagnosis of cancer was associated with shorter use (HR=2.73, 95% CI=2.02-3.67). In Manitoba, Canada approximately 18% of people prescribed cannabinoid medication continue using for at least 1 year. Duration of use varies with type of cannabinoid medication, age, socio-economic status and dagnosis.