Pharmaceutical cannabinoid use in Manitoba, 2004/05 to 2014/15: a population-based cross-sectional study.

BACKGROUND:

Pharmaceutically derived cannabinoids are used for several indications, particularly pain management. The extent of their use from a population perspective is unknown; hence, the aim of this study was to evaluate trends in pharmaceutical cannabinoid use in Manitoba.

METHODS:

This was a retrospective population-based cross-sectional study using administrative data from the Manitoba Centre for Health Policy. Pharmaceutical cannabinoid users residing in Manitoba from Apr. 1, 2004, to Mar. 31, 2015 were identified. We assessed the annual prevalence and incidence of pharmaceutical cannabinoid use, and the sociodemographic characteristics and medical conditions of users.

RESULTS:

We identified 5181 people who received at least 1 prescription for a pharmaceutical cannabinoid over the study period, 5033 of whom received their first prescription after Apr. 1, 2004. Nabilone accounted for 73 650 (96.0%) of all prescriptions dispensed; dronabinol was discontinued during the study period. The annual prevalence rate of use increased by 527.2%, from 21.5 (95% confidence interval [CI] 21.4-21.6) users per 100 000 people in 2004/05 to 134.9 (95% CI 134.7-135.1) users per 100 000 people in 2014/15. The annual incidence rate increased by 413.3%, from 12.1 (95% CI 12.1-12.2) users per 100 000 person-years in 2004/05 to 62.2 (95% CI 62.1-62.4) users per 100 000 person-years in 2014/15. The highest use was among older adults aged 46-64 years, females and urban area residents. One-third of incident users (1775 [35.3%]) had a diagnosis of fibromyalgia in a 2-year period before their first cannabinoid prescription. General practitioners initiated almost half (2350 [46.7%]) of first prescriptions, and anesthesiologists/pain specialists initiated one-quarter (1299 [25.8%]).

INTERPRETATION:

The prevalence and incidence of pharmaceutical cannabinoid use increased over time. These findings provide insight into the use of cannabinoids before the introduction of recreational marijuana, which may affect this trend.

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