Efficacy of Controlled-Release Paroxetine in the Treatment of Late-Life Depression

Background: Depression is the second most common neuropsychiatric disorder in older Americans, with significant clinical and public health costs. Despite advances in treatment, late-life depression remains a clinical challenge. Although the selective serotonin reuptake inhibitors (SSRIs) are the most common pharmacologic intervention for late-life depression, few placebo-controlled trials have assessed the efficacy of SSRIs for this condition.

Method: In this 12-week, multicenter, placebo-controlled, flexible-dose, double-blind, randomized trial, 319 elderly patients (mean age = 70 years) were treated with controlled-release paroxetine (paroxetine CR) up to 50 mg/day (N = 104), immediate-release paroxetine (paroxetine IR) up to 40 mg/day (N = 106), or placebo (N = 109). Patients met DSM-IV criteria for major depressive disorder and had a total score of 18 or more on the 17-item Hamilton Rating Scale for Depression (HAM-D). The primary efficacy measure was change from baseline to endpoint in HAM-D total score.

Results: The primary efficacy analysis showed an adjusted difference between change from baseline in HAM-D score for paroxetine CR and placebo of -2.6 (95% confidence interval [CI] = -4.47 to -0.73, p = .007) at the week 12 last-observation-carried-forward (LOCF) endpoint. The adjusted difference between paroxetine IR and placebo was -2.8 (95% CI = -4.65 to -0.99, p = .003) at week 12. Paroxetine CR and IR were more effective than placebo, with mean ± SD endpoint HAM-D total scores of 10.0 ± 7.41 and 10.0 ± 7.10, respectively, for the active treatments compared with 12.6 ± 7.34 for placebo. Response, defined as a score of 1 or 2 on the Clinical Global Impressions-global improvement scale, was achieved by 72% of paroxetine CR patients (LOCF; p < .002 vs. placebo), 65% of paroxetine IR patients (p = .06 vs. placebo), and 52% of placebo patients. Remission, defined as a HAM-D total score <= 7, was achieved by 43% of paroxetine CR patients (LOCF; p = .009 vs. placebo), 44% of paroxetine IR patients (p = .01 vs. placebo), and 26% of placebo patients. In a post hoc analysis, mean HAM-D improvement for paroxetine CR and paroxetine IR was greater than for placebo in both chronically depressed patients (duration > 2 years) and those with short-term (<= 2 years) depression. Dropout rates due to adverse events were 12.5% for paroxetine CR, 16.0% for paroxetine IR, and 8.3% for placebo.

Conclusion: Paroxetine CR and paroxetine IR are effective and well tolerated treatments for major depressive disorder in elderly patients, including those with chronic depression.