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

Abstract

Objectives

Depression 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.

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.

Keywords:

• Depression
• pain
• disability
• quality of life
• prognosis
• primary care

ACKNOWLEDGEMENT

This study was supported by a grant from the National Institute of Mental Health to Dr Kroenke (MH-071268).

Declaration of interest: Dr Kroenke has received honoraria from Eli Lilly and Forest for serving on an advisory board and for speaker fees. None of the other authors have any financial or personal disclosures.