Impact of pain on depression treatment response in primary care

Objective: Pain commonly coexists with depression, but its impact on treatment outcomes has not been well studied. Therefore, we prospectively evaluated the impact of comorbid pain on depression treatment response and health-related quality of life. Methods: We analyzed data from the ARTIST study, a randomized controlled trial with naturalistic follow-up conducted in 37 primary care clinics. Participants were 573 clinically depressed patients randomized to one of three selective serotonin reuptake inhibitor (SSRI) antidepressants: fluoxetine, paroxetine, or sertraline. Depression as assessed by the Symptom Checklist-20 (SCL-20) was the primary outcome. Secondary outcomes included pain and health-related quality of life. Results: Pain was reported by more than two thirds of depressed patients at baseline, with the severity of pain mild in 25% of patients, moderate in 30%, and severe in 14%. After 3 months of antidepressant therapy, 24% of patients had a poor depression treatment response (ie, SCL-20 > 1.3). Multivariate odds ratios for poor treatment response were 1.5 (95% confidence interval, 0.8-3.2) for mild pain, 2.0 (1.1-4.0) for moderate pain, and 4.1 (1.9-8.8) for severe pain compared with those without pain. Increasing pain severity also had an adverse impact on outcomes in multiple domains of health-related quality of life. Conclusions: Pain is present in two thirds of depressed primary care patients begun on antidepressant therapy, and the severity of pain is a strong predictor of poor depression and health-related quality of life outcomes at 3 months. Better recognition, assessment, and treatment of comorbid pain may enhance outcomes of depression therapy.