Impact of depression on 12-month outcomes in primary-care patients with chronic musculoskeletal pain

Objectives Depression complicates chronic pain in 3050 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.Methods A 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.Results Patients 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.Conclusions Patients 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.