SSRI antidepressant use patterns and their relation to clinical global impression scores: a naturalistic study

Background: A cascade of events follows initial antidepressant selection which includes the subsequent antidepressant use pattern, resultant clinical outcomes, and associated health care expenditures. Purpose: The purpose of this study using data from a clinical practice setting was to test whether the pattern of antidepressant use was correlated with patients' treatment response as measured by the score on the Clinical Global Impression-Improvement scale. Data and Method's: A retrospective dataset of patients who initiated therapy on fluoxetine, fluvoxamine, paroxetine, or sertraline in a primary care setting in Spain was used. A Cox proportional hazard analysis was used to predict the likelihood of treatment response based upon the pattern of initial antidepressant use, while minimizing the influence of other factors. Results: After controlling for other observed baseline characteristics including initial disease severity, (a) patients who remained on their initial antidepressant therapy for at least 2 months with no switching, augmentation, or upward dose titration were 1.63 times more likely to experience a treatment response than patients who had an adjustment to therapy; and (b) patients who initiated therapy on sertraline were 0.46 times as likely to experience a treatment response as patients who initiated therapy on the most common study antidepressant, fluoxetine. Conclusion: The pattern of antidepressant use is an important determinant of treatment response among patients initiating therapy on the newer antidepressants in clinical practice. (C) 1999 Elsevier Science B.V. All rights reserved.