Preventing recurrent depression using cognitive therapy with and without a continuation phase: a randomized clinical trial

Abstract

Background: Cognitive therapy (CT) may reduce depressive relapse and recurrence when patients learn and use the associated skills. Reported relapse and recurrence rates after CT discontinuation vary widely. The factors that determine when CT is preventive remain unidentified. We developed continuation-phase CT (C-CT) to teach responders skills to prevent relapse. This is the first randomized trial comparing CT with and without a continuation phase in responders to CT who were vulnerable, given their history of recurrent unipolar depression.

Methods: Patients aged 18 to 65 years (n = 156) with recurrent DSM-IV major depressive disorder (MDD) entered 20 sessions of acute-phase CT (A-CT). Unmedicated responders (ie, no MDD and 17-item Hamilton Rating Scale for Depression score < or =9; n = 84) were randomized to either 8 months (10 sessions) of C-CT or control (evaluation without CT). Follow-up lasted an additional 16 months. A clinician blind to assignment evaluated relapse and recurrence (ie, DSM-IV MDD).

Results: Over an 8-month period, C-CT significantly reduced relapse estimates more than control (10% vs 31%). Over 24 months, including the CT-free follow-up, age of onset and quality of remission during the late phase of A-CT each interacted with condition assignment to influence durability of effects. In patients with early-onset MDD, C-CT significantly reduced relapse and recurrence estimates (16% vs 67% in control). When patients had unstable remission during late A-CT, C-CT significantly reduced relapse and recurrence estimates to 37% (vs 62% in control).

Conclusions: Findings suggest that 8 months of C-CT significantly reduces relapse and recurrence in the highest-risk patients with recurrent MDD. Risk factors influenced the necessity for C-CT.

Pretreatment Demographic and Clinical Characteristics of Outpatients With Recurrent Major Depressive Disorder

Figure 1

Flow diagram for patients through all study phases, including attrition. Subjects (n=156) were registered in the study on consenting to acute-phase cognitive therapy (A-CT). Eligible responders were randomized to the clinical trial (N=84). C-CT indicates continuation-phase CT.

Figure 2

Kaplan-Meier survival curves estimating time until relapse (DSM-IV major depressive disorder diagnosed by blind evaluation) during the 8-month (35-week) experiment. A log-rank test showed that continuation-phase cognitive therapy (C-CT) reduced the proportion of relapse significantly more than control (CT-free evaluation) (χ²₁=5.26, P=.02). Estimated relapse was 10% for C-CT patients and 31% for controls (n=41 and n=43, respectively).

Figure 3

Kaplan-Meier survival curves estimating time until relapse or recurrence (DSM-IV major depressive disorder diagnosed by blind evaluation) during 24 months (102 weeks). A log-rank test revealed significant interaction between condition (continuation-phase cognitive therapy [C-CT] or control [CT-free evaluation]) and age of onset (early, ≤18 years; late, >18 years) (χ²₃=10.09, P=.02).

Figure 4

Kaplan-Meier survival curves estimating time until relapse or recurrence (DSM-IV major depressive disorder diagnosed by blind evaluation) during 24 months (102 weeks). A log-rank test produced significant interaction between condition (continuation-phase cognitive therapy [C-CT] or control [CT-free evaluation]) and stability of acute-phase CT remission (stable and unstable) (χ²₃=8.67, P=.03).