Objective: This article uses data from two studies that have demonstrated the overall effectiveness of Collaborative Care interventions to evaluate factors associated with poor outcomes overall (general prognostic factors) and factors associated with greater or lesser effects of treatment (differential treatment effects).
Methods: Adult primary care patients initiating antidepressant treatment for major depression were randomized to usual care or to Collaborative Care, a structured depression treatment program that included planned, proactive and coordinated care with a health care team and informed, activated patients (n = 156, mean age = 43, 85% white). Response to treatment was defined as a 50% or greater reduction in depression at four months.
Results: High neuroticism and a history of recurrent major depression (3+ episodes) or dysthymia predicted poor outcomes in general. While the magnitude of the intervention effects differed, frequently cited predictors of persistence of depression (age, gender, depression severity, medical and psychiatric comorbidity) were not significantly associated with greater or lesser benefit from Collaborative Care (no differential treatment effects). Results demonstrate the robustness of intervention effects across numerous groups at risk for persistence of depression.
Conclusions: These findings suggest that at the time of diagnosis it is not possible to predict who is most likely to benefit from Collaborative Care. Instead, outcomes of treatment should be routinely monitored among depressed patients to ensure optimal response.