Journal: Pain 157 (2016) 1472–1479
Authors: Lauren Rayner, Matthew Hotopf, Hristina Petkova, Faith Matcham, Anna Simpson, Lance M. McCracken
A high rate of comorbidity exists between chronic pain and depression. In addition, chronic pain sufferers who also have depression have been shown in studies to have poorer health outcomes, including reduced response to treatment. Individuals with comorbid chronic pain and depression use more health care services than those with chronic pain alone, resulting in substantial annual health care costs in the US.
To determine the prevalence of depression in a chronic pain patient population, and assess the impact of depression on health care utilization and costs.
The study evaluated patients involved in a tertiary pain management service for people with chronic pain, unresponsive to medical treatment. Patients completed a questionnaire assessing mental health, physical health, functioning, and service use in the preceding 3 months. Depression was assess using the PHQ-9, with severe depression being benchmarked at a score of 20-27, moderate depression at 15-19, and mild depression at <15.
Self-report health care utilization was measured via general practitioner contacts, contacts with specialists, emergency department visits, and days hospitalized.
1,204 patients completed the questionnaires. 2/3 were women, median age was 47, median duration of pain was 7 years, and 53% were unable to work for health reasons. 60.8% of patients met criteria for probable Major Depressive Disorder (MDD), with 33.8% severe, 21.3% moderate, and 15.2% reporting having had suicidal thoughts.
Patients with depression were more likely to be unable to work due to health considerations. They also reported more work absences, greater impairment to functioning, lower pain acceptance, and more generalized pain.
Mean total health care costs per 3-month period were £731 for patients with depression, compared with £448 for patients without depression. A larger portion of the depressed patients visited general practitioners, specialists, and had hospital admissions, indicating higher use of medical services.
This study demonstrates a high comorbidity rate of depression with chronic pain, and shows a link to higher health care utilization and health care costs, even after controlling for key demographic, functional, and clinical covariates using multiple linear regression models. These findings reveal the extent, severity, and impact of depression in patients with chronic pain. Effective treatment of depression may improve patient health and functioning and reduce the burden of chronic pain on health care services.