Effects of age on paroxetine efficacy in patients with major depressive disorder who do not exhibit an early response to treatment.

Objectives: We investigated the effects of age on the association between early and eventual responses to paroxetine treatment in patients with major depressive disorder (MDD).

Methods: Eighty-nine patients with MDD were administered paroxetine and completed the 6-week protocol. On the basis of our previous study, we defined early responders as those patients with the Montgomery-Asberg Depression Rating Scale (MADRS) improvements higher than 35% at 2 weeks and responders as those patients with MADRS improvements higher than 50% at 6 weeks. The participants were divided into 4 groups in accordance with their responses: early response responders, early response nonresponders, nonearly response responders (NER-Rs), and nonearly response nonresponders (NER-NRs). Demographic data and the MADRS scores between the early response responders and the early response nonresponders and between the NER-Rs and the NER-NRs were compared. We used a receiver operating characteristic (ROC) curve to analyze age to determine the cutoff points for distinguishing responders and nonresponders in early and nonearly responders.

Results: There was a significant difference in age between the NER-Rs and the NER-NRs, with the NER-Rs being younger than the NER-NRs. The threshold for the response in the early responders was 42 years old. The area under the curve of the ROC curve of the early responders was 0.548. The threshold for the response of the nonearly responders was 55 years old. The area under the curve of the ROC curve of the early responders was 0.733.

Conclusions: The effects of age on the association between the responsiveness in the early phase of antidepressant treatment and the eventual response were identified in patients with MDD.