Selective serotonin reuptake inhibitor use in primary care: a 5-year naturalistic study.

Objective: To investigate prescribing trends of selective serotonin reuptake inhibitors (SSRIs) during the course of the Defeat Depression Campaign (1992 to 1996).

Methods: This study utilised cross-sectional data on the prescribing of SSRIs for the treatment of depression from a large primary care database for the 5 consecutive years of the Defeat Depression Campaign, producing the largest study of SSRI use to date.

Results: A total of 93 600 prescriptions were issued for fluoxetine, paroxetine and sertraline, in 27 210 treatment episodes. Over the 5-year period, there was a five-fold increase in the number of prescriptions issued, and a four-fold increase in the number of patients treated, reflecting a trend for longer periods of treatment. Patients initiating treatment with fluoxetine were most likely and those initiating treatment with sertraline were least likely to complete 60, 90 and 120 consecutive days of treatment. Differences in dose patterns also emerged and were consistent throughout the study. Fluoxetine-treated patients were most likely to remain on the starting dose of 20mg daily, while large numbers of sertraline-treated patients received doses above the recommended dose of 50mg daily. These differences were not apparent from clinical trials, and this may be an artefact of trial design.

Conclusion: Differences in the doses prescribed may explain why sertraline-treated patients are less likely to complete an adequate course of antidepressant therapy. Longitudinal studies are required to evaluate fully the clinical significance of these findings.