Impact of Depression on 12-Month Outcomes in Primary-Care Patients with Chronic Musculoskeletal Pain

ObjectivesDepression complicates chronic pain in 30–50 percent of patients. Our objectives were to determine the 12-month clinical outcomes in patients with chronic musculoskeletal pain and the effects of comorbid depression.MethodsA cohort of 377 primary care patients with low back, hip, or knee pain for at least three months were enrolled, including 127 with depression of at least moderate severity [Patient Health Questionnaire-9 score ≥ 10] and 250 without depression. Telephone assessments were done at baseline, three, and 12 months by interviewers blinded to group status. Outcomes included pain severity, pain self-efficacy, disability, and pain-specific health care use, as well as depression, anxiety, somatization, stress, and quality of life.ResultsPatients with comorbid depression had moderately greater pain severity and substantially worse pain-related disability as well as greater impairment across multiple symptom and health-related quality of life domains. This adverse effect of depression persisted at three- and 12-month follow-up. Rates of improvement in pain were low and did not differ between groups [16.5 versus 19.8 percent], but depressed patients were significantly more likely to report worsening of pain at 12 months [35.0 versus 18.5 percent, P < 0.0001]. Development of incident depression was uncommon. Self-reported pain-specific treatments and healthcare use were similar in the two groups.ConclusionsPatients with chronic pain and comorbid depression have substantially worse disability and health-related quality of life, which persists over long-term follow-up. Diligent efforts to identify and treat depression could potentially improve pain.