Impact of prior treatment exposure on response to antidepressant treatment in late life

Objective: The objective of this study was to describe the correlates of prior antidepressant exposure and its association with response to protocolized treatment in older patients with major depression. Methods: Based on their prior antidepressant treatment exposure, 193 elderly patients with a major depressive episode were divided into three groups: those with no prior treatment for their current episode (not treated [TN]), those with antidepressant trials of inadequate dose or duration ("treatment-inadequate" [TN]), and those with at least one adequate trial but persisting depression ("treatment- resistant" [TR]). All patients then received protocolized treatment with interpersonal psychotherapy (IPT) and paroxetine plus pharmacologic augmentation if needed. The demographic, clinical, and outcome information were compared among these three groups. Results: Approximately one-third of the patients referred to the study had been adequately treated (TR), one-third had been inadequately treated (TI), and one-third were not treated for the current episode (TN). Treatment completion rates and reasons for dropping out did not differ statistically among TR, TI, and TN patients. TR patients took longer to respond (13.0 weeks) than either TI or TN patients (7.6 and 8.0 weeks, respectively). TR and TI patients had lower response rates (67% and 71%) than TN patients (86%). Conclusions: Prior treatment exposure is an important correlate of course and outcome in late-life depression. Most TR and TI patients eventually respond, but TR patients may require more intensive and longer courses of treatment than TI and TN patients.