Increased use of antidepressants in Canada: 1981-2000

To provide a descriptive analysis of Canadian utilization (prescriptions, cost, cost per prescription) of antidepressants (ATC-code: N06A).

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.

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 dollars. Total expenditures for antidepressants increased exponentially, from 31.4 million dollars in 1981 to 543.4 million dollars in 2000 (y = 4E - 130e(0.1556x) [R(2) = 0.99]). Cost per prescription increased linearly from 9.85 dollars in 1981 to 37.44 dollars in 2000 (y = 1.72x + 7.92 [R(2) = 0.96]).

Utilization and costs of pharmacotherapy for depression have increased above the inflation rate and are expected to exceed 1.2 billion dollars (50 dollars 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.