Use of antidepressants among elderly subjects: Trends and contributing factors

Objective: The authors assessed changes over time in antidepressant utiliza tion among elderly subjects regarding the prevalence of antidepressant user s, shifts in prescription patterns, and related financial implications. Met hod: The authors conducted a population-based study of more than 1.4 millio n Ontario residents aged 65 years or older. Cross-sectional data regarding annual antidepressant utilization were obtained from administrative databas es for 1993 to 1997. Time series analysis was used to assess trends over ti me and to make future projections. Results: The proportion of antidepressan t users increased from 9.3% of the elderly population in 1993 to 11.5% in 1 997. Prescriptions for selective serotonin reuptake inhibitors (SSRIs) acco unted for 9.6% of antidepressant prescriptions dispensed in the first 30 da ys of 1993 and 45.1% of those dispensed by the last 30 days of 1997 and wer e projected to increase to approximately 56% by the end of 2000. Prescripti ons for tricyclic antidepressants fell from 79.0% in the first 30 days of 1 993 to 43.1% by the last 30 days of 1997 and were projected to decline to a pproximately 28% by the end of 2000. Annual antidepressant costs (in Canadi an dollars) increased by 150%, from $10.8 million in 1993 to $27.0 million in 1997. Population shifts and an increase in the prevalence of antidepress ant users accounted for at least 20% of this increase, whereas the prescrib ing transition from tricyclic antidepressants to SSRIs accounted for at lea st 61% of the increase. Conclusions: The introduction of SSRIs has had a su bstantial financial impact at the drug utilization level. Future research s hould address the appropriate balancing of the cost of newer agents versus their ostensible advantages.