Impact of Pretreatment With Antidepressants on the Efficacy of Duloxetine in Terms of Mood Symptoms and Functioning

OBJECTIVE: This post hoc analysis aimed to determine whether patients with major depressive disorder (MDD) in duloxetine trials who were antidepressant naive or who were previously exposed to antidepressants exhibited differences in efficacy and functioning. METHOD: Data were pooled from 15 double-blind, placebo- and/or active-controlled duloxetine trials of adult patients with MDD conducted by Eli Lilly and Company. The individual studies took place between March 2000 and November 2009. Data were analyzed using 4 pretreatment subgroups: first-episode never treated, multiple-episode never treated, treated previously only with selective serotonin reuptake inhibitors (SSRIs), and previously treated with antidepressants other than just SSRIs. Measures included the 17-item Hamilton Depression Rating Scale (HDRS-17) total and somatic symptom subscale scores, Montgomery-Asberg Depression Rating Scale (MADRS) total score, and Sheehan Disability Scale total score. Response rates (50% and 30%) were based on the HDRS-17 total score and remission rates on either the HDRS-17 or MADRS total score. RESULTS: Response and remission rates were significantly greater (P < .05 in 11 of 12 comparisons) for duloxetine versus placebo in the 4 subgroups. A trend of greater response and remission occurred for first-episode versus multiple-episode patients; both groups were generally higher than the antidepressant-treated groups. Mean changes in efficacy measures were mostly significantly greater (P < .05 in 13 of 16 comparisons) for duloxetine versus placebo within each pretreatment subgroup, with some (P < .05 in 2 of 24 comparisons) significant interaction effects between subgroups on HDRS-17 total and somatic symptoms scores. CONCLUSIONS: Duloxetine was generally superior to placebo on response and remission rates and in mean change on efficacy measures. Response and remission rates were numerically greater for first-episode versus multiple-episode and drug-treated patients. Mean change differences on efficacy measures among the 4 subgroups were inconsistent. Duloxetine showed a similar therapeutic effect independent of episode frequency and antidepressant pretreatment.