Are there differences in the use of selective serotonin reuptake inhibitors and tricyclic antidepressants? A prescription database study

Aim: The aim of the present study was to analyse the utilisation of antidepressants (ADs) and to compare the utilisation of the various ADs with special reference to duration of treatment courses. Method: Fro m the Odense Pharmacoepidemiologic Database (OPED), all users of and prescriptions for ADs in the County of Funen, Denmark (about 470,000 inhabitants), were identified for each year from 1992 to 1997 (6 years). Duration of treatment courses was calculated for the first incident period of continuous use of one AD and was compared for the various ADs using Kaplan-Meiers survival statistics with log rank tests. Continuous use was defined as use of a minimum of one tablet per day. Furthermore, the proportion of users presenting only one prescription was determined for each AD. Results: In total, 37,598 patients presented 392,524 prescriptions during 1992-1997. The 1-year prevalence rose from 2.1% to 4.1% in 1997 and the incidence was 1.3% in 1997. The I-year prevalence increased with age up to 16.5% in 1997 for patients aged 90 years or older. Citalopram was the most-used AD, but there were still a considerable number of patients commencing treatment with TCAs in 1997. Median duration of treatment courses was 196 days for TCAs versus 120 days for SSRIs (P < 0.0001). Duration of treatment courses increased with age. The proportion of users presenting only one prescription was 22% for the SSRIs versus 33% for tricyclic antidepressants (TCAs). Conclusion: This study showed that the use of ADs continues to increase because of the increase in the use of the new ADs. There was, however, still a considerable number of patients who started on TCA treatment in 1997. For repeated prescriptions, TCAs were used for longer times than SSRIs. In the very old, there was an apparently inappropriate high use of ADs.