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

Abstract 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 Methods: 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.