Antidepressant Medication Change in a Clinical Treatment Setting: A Comparison of the Effectiveness of Selective Serotonin Reuptake Inhibitors

Background: This investigation focuses on the 3 most frequently used selective serotonin reuptake inhibitors (SSRIs) (paroxetine, fluoxetine, sertraline) and examines the rate of medication switches as a measure of effectiveness. We answer 2 questions: (1) What is the likelihood that a patient starting treatment with an SSRI will complete treatment with the same agent? and (2) Depending on the initial SSRI agent used, do patients switch at different frequencies?

Method: A retrospective chart review was performed on 2779 patients treated in a university outpatient clinic from March 1995 to January 1997. Of these, 263 patients given antidepressants were randomly selected: 214 were prescribed SSRIs; 24, novel antidepressants; and 25, tricyclic antidepressants.

Results: There was no significant difference in rate of switching between the different classes of antidepressant (p = .1) nor between drugs within the SSRI class (p = .513). When medication change was the independent factor, significant differences between the groups were total time in treatment and number of visits (p < .001 and p = .011, respectively). Age, education, and Clinical Global Impressions-Severity of Illness scale scores (admission, discharge, and change) were not significantly different between the groups.

Conclusion: Approximately 25% of patients started with an SSRI will switch to another antidepressant in the course of their treatment. The SSRIs appear to be equivalent in effectiveness. They are not interchangeable, because patients who discontinue one SSRI for lack of tolerability or response can generally be treated effectively with another.