Increased use of antidepressants in Canada: 1981-2000

OBJECTIVE: To provide a descriptive analysis of Canadian utilization (prescriptions, cost, cost per prescription) of antidepressants (ATC-code: N06A). METHODS: IMS Canada provided prescription volumes and costs from 1981 to 2000. We analyzed time trends for antidepressants in general and 4 subclasses (tricyclic antidepressants [TCAs], selective serotonin-reuptake inhibitors [SSRIs], dual action antidepressants [DAAs], and monoamine oxidase inhibitors [MAOIs]). Costs were discounted using the consumer price index, adjusting for population growth using data from Statistics Canada. RESULTS: Between 1981 and 2000, total prescriptions increased from 3.2 to 14.5 million. Market share of TCAs (23.7%) and MAOIs (2.1%) remained constant, despite the introduction of the first SSRI, fluoxetine, in 1989. SSRI prescriptions increased to 6.7 million (market share 46.3%). DAA use increased gradually after 1994 to 3.5 million prescriptions (23.9% market share) in 2000. The number of prescriptions expanded (possibly due to SSRIs) by 238%, with an increased cost of $2.7 billion. Total expenditures for antidepressants increased exponentially, from $31.4 million in 1981 to $543.4 million in 2000 (y = 4E - 130e(0.1556x) [R-2 = 0.99]). Cost per prescription increased linearly from $9.85 in 1981 to $37.44 in 2000 (y = 1.72x + 7.92 [R-2 = 0.96]). CONCLUSIONS: Utilization and costs of pharmacotherapy for depression have increased above the inflation rate and are expected to exceed $1.2 billion ($50 per prescription) in 2005. Increased costs may be due to increased availability of new products with increased safety, efficacy, and acquisition cost; increased number of users; and increasing costs.