Background: This study describes the functioning of primary care patients with major depressive disorder, the relationship of medical comorbidity to functional status, and the effects of depression-specific treatment on functional status after 8 months.
Methods: Patients were randomized to a protocol intervention (nortriptyline hydrochloride or interpersonal psychotherapy) or to usual care with the patient's physician in a clinical trial of primary care treatments of depression. Their functional status was evaluated using the Medical Outcomes Study 36-Item Short Form Health Survey (SF-36) and the Global Assessment Scale. Medical comorbidity was assessed with the Duke Severity of Illness Checklist. The Hamilton Rating Scale for Depression and Beck Depression Inventory were used to measure depressive severity. Assessments were conducted at baseline and at 1, 2, 4, and 8 months after randomization.
Results: At baseline, patients reported substantial impairments in the functional domains as assessed by the SF-36 and Global Assessment Scale. Severity of general medical illness and depression were not correlated. Greater medical comorbidity was associated with diminished physical, but not psychological, functioning. Mean scores on SF-36 scales and the Global Assessment Scale improved significantly during the 8 months of follow-up. Patients assigned to protocol treatments showed greater improvement, compared with those assigned to usual care, on the SF-36 mental summary scale and most individual scales but not on the SF-36 physical summary scale. However, patients who completed protocol treatment also experienced significant improvement on the physical summary scale. Medical comorbidity was only a weak predictor of outcome.
Conclusions: Primary care patients with major depressive disorder report substantial impairments in physical, psychological, and social functioning on initial assessment. Severity of baseline medical comorbidity did not correlate with severity of depression and only weakly correlated with functional status at 8 months. Functional impairments improve with time, but standardized depression-specific treatment is associated with greater improvement in more domains of functioning than is a physician's usual care.