Major depressive disorder is the most common major mental illness, afflicting almost one in five individuals. More than 75 percent of people who recover from an episode of MDD will have at least one recurrence, with the majority having multiple recurrences.
MDD is the leading cause of disability of all medical illnesses, with substantial functional impairment, morbidity, and mortality. Few studies have assessed the efficacy of antidepressant medications beyond 1 year of maintenance treatment for the prevention of recurrent depression. However, a new study being published in the upcoming December 15th issue of Biological Psychiatry has done just that.
The PREVENT study, an acronym for the title of the study "The Prevention of Recurrent Episodes of Depression with Venlafaxine for Two Years study," is, according to one of the senior authors on the paper, Dr. Martin B. Keller, "a multiphase, double-blind, randomized clinical trial designed to investigate the efficacy of the serotonin-norepinephrine reuptake inhibitor (SNRI) venlafaxine extended release in the prevention of depressive recurrence over 2 years in patients with a history of recurrent MDD who have responded to acute and continuation treatment." The investigators randomly assigned patients with recurrent depression to receive treatment with either venlafaxine extended-release (ER) or fluoxetine, an antidepressant already established as efficacious as a comparative medication. Although the PREVENT study followed patients for over two years, this article reports only on the acute and continuation phases, which were 10 weeks and 6 months long respectively.
Dr. Keller notes that this study "has several novel aspects to its design and methods," including its very large sample size, and long period of blinded treatment, where neither the physicians nor patients knew which medication the patient was receiving. The authors found that nearly 80% of the patients achieved at least an adequate therapeutic response to acute phase treatment with venlafaxine ER or fluoxetine, and almost none of the responders who continued on treatment for 6 months relapsed.
Husseini K. Manji, M.D., FRCP(C), Deputy Editor of Biological Psychiatry and Director of the Mood and Anxiety Disorders Program at the National Institute of Mental Health, comments on the study's findings:
"Major depression is a serious, debilitating, life-shortening illness that affects millions of people worldwide. This is thus an important study that shows surprisingly high response and remission rates. For many patients, major depression is a chronic illness characterized by multiple episodes of symptom exacerbation, residual symptoms between episodes, and functional impairment. Thus, the ability to maintain patients in remission is critical to reducing long-term disability."
In addition to the high response rates by the patients in this study, the rates of adverse events (side effects) were similar among the two treatment groups. Dr. Manji does issue a caution though with regard to generalizing the findings, noting that "the investigators studied a group of patients whose course of illness was not chronic. Furthermore, they excluded patients with a history of treatment resistance or significant comorbid illnesses." However, he added that "if replicated, the results suggest that there may be a subgroup of depressed patients for whom early and sustained treatment can maintain response and prevent relapses." Dr. Keller remarks that these results are "critical to clinical practice and should be considered when choosing a treatment for patients with recurrent MDD."