Predictors of outcome in a primary care depression trial

OBJECTIVE: Previous treatment trials have found that approximately one thir d of depressed patients have persistent symptoms. We examined whether depre ssion severity, comorbid psychiatric illness, and personality factors might play a role in this lack of response. DESIGN: Randomized trial of a stepped collaborative care intervention versu s usual care. SETTING: HMO in Seattle, Wash. PATIENTS: Patients with major depression were stratified into severe (N = 1 49) and mild to moderate depression (N = 79) groups prior to randomization. INTERVENTIONS: A multifaceted intervention targeting patient, physician, an d process of care, using collaborative management by a psychiatrist and pri mary care physician. MEASUREMENTS AND MAIN RESULTS: Patients with more severe depression had a h igher risk for panic disorder (odds ratio [OR], 5.8), loneliness (OR, 2.6), and childhood emotional abuse (OR, 2.1). Among those with less severe depr ession, intervention patients showed significantly improved depression outc omes over time compared with those in usual care (z = -3.06, P < .002); how ever, this difference was not present in the more severely depressed groups (z = 0.61, NS). Although the group with severe depression showed differenc es between the intervention and control groups from baseline to 3 months th at were similar to the group with less severe depression (during the acute phase of the intervention), these differences disappeared by 6 months. CONCLUSIONS: Initial depression severity, comorbid panic disorder, and othe r psychosocial vulnerabilities were associated with a decreased response to the collaborative care intervention. Although the intervention was appropr iate for patients with moderate depression, individuals with higher levels of depression may require a longer continuation phase of therapy in order t o achieve optimal depression outcomes.