Chronic Pain, Depression, and Quality of Life

Correlations and Predictive Value of the SF-36

Elliott, Thomas E. MD, FACP
Renier, Colleen M. BS
Palcher, Jeanette A. BA

^*Division of Education and Research, St. Mary's/Duluth Clinic Health System, Duluth, Minnesota
^†SMDC Pain Management Center, St. Mary's/Duluth Clinic Health System, Duluth, Minnesota

Reprint requests to: Thomas E. Elliott, MD, FACP, Medical Director, Division of Education and Research and SMDC Pain Management Center, St. Mary's/Duluth Clinic Health System, 503 East Third Street, Duluth, MN 55805. Tel: (218) 786-3755; Fax: (218) 727-8159; E-mail: [email protected]

Pain Medicine 4(4):p 331-339, December 2003.

Objective

Depression is a major barrier to effective pain relief. The SF-36 Health Survey may be useful as an outcome measure for chronic pain patients with and without depression. The study purpose was to determine the correlation between the SF-36 Mental Composite Scale t-score and depression type in chronic pain patients and the positive predictive value of the SF-36 in classifying depression type in chronic pain patients.

Design

Cross-sectional survey of chronic pain patients at baseline assessment.

Setting

Interdisciplinary pain management center in the North Central United States.

Patients

Two hundred forty-two consecutive, chronic noncancer pain patients.

Interventions

Assessments of patient-reported health-related quality of life (SF-36), pain, pain type and diagnoses, mental health diagnoses, and patient demographics.

Outcome Measures

SF-36 Health Survey, pain diagnoses, and depression diagnoses.

Results

Study participants were 160 women (66%) and 82 men (34%), 95% Caucasian, whose mean age was 46 (±0.8 SD) years (range: 19–83). All types and diagnoses of chronic pain were represented. The prevalence of major depressive disorder was 52%. The type of depression was highly correlated with SF-36 score (r =−0.567; P < 0.001). All chronic pain patients had very low SF-36 scores. Compared with U.S. population norms, chronic pain patients with and without depression had significantly lower SF-36 scores as measured by z-scores. Chronic pain patients with major depressive disorder had a significantly lower Mental Composite Score t-score than those with minor or no depression—34.1 and 47.6, respectively (P < 0.001). The positive predictive value of the SF-36 for differentiating major depression from minor or no depression was 98% (sensitivity = 84.4%, specificity = 93.9%).

Conclusions

The SF-36 Mental Composite Score and all subscales were highly correlated with depression type in chronic pain patients. The positive predictive value of the SF-36 in classifying depression type was high. The SF-36 may be a useful clinical tool to measure health-related quality of life in chronic pain patients. In addition, the SF-36 was able to detect major depression and demonstrate a dose-effect relationship between depression type (severity) and health-related quality of life in chronic pain patients.