Background data: Depression is a common co-morbidity for patients with complaints of spinal pain, yet often goes undiagnosed in clinical practice. Depressed patients who are not identified do not receive a referral or recommendation for treatments that may help ease their total illness burden. Relative to the total outcomes of spine care this may increase costs, decrease overall functional outcomes, and limit patient satisfaction. Some spine care settings track functional outcomes using a general health status survey. Although a specific and reliable survey to detect depression could be employed, an additional survey would unnecessarily increase responder and analyst burdens if the general health status survey could be used instead.
Objective: To identify the Mental Component Summary (MCS) cutoff score from the Short Form 36-item Health Survey (SF-36) that best predicts a positive depression score as measured by the Center for Epidemiological Study-Depression Survey (CES-D).
Study design: An analysis of the diagnostic properties of the SF-36 MCS Scale as a predictor of depressive symptoms as measured by the CES-D.
Outcome measures: The SF-36 is a general health survey that contains a MCS score that represents the psychological well-being and general health perception of the respondent. This composite score is norm-based (mean = 50, SD = 10) with lower scores representing poorer health. The CES-D has been well-studied in patients with chronic pain complaints and was used as the gold standard for determining the MCS cutoff score. A CES-D score of 19 or greater was considered positive for depressive symptoms.
Patient sample: All patients entering our facility routinely complete the SF-36. Between February 2002 and October 2002, all patients scoring 30 or less on the MCS (MCS < or = 30) also completed the CES-D. Patients who scored 2 standard deviations below the mean (MCS = 30 or less) were considered most at risk for depression. Patients scoring above 30 on their MCS (MCS > 30) were considered less likely to have depressive symptoms and were randomly chosen to complete the CES-D. There were 420 patients who completed both surveys of which there were 99 MCS < or = 30 patients and 321 MCS > 30 patients.
Methods: Receiver operating characteristic (ROC) curves were used to assess the sensitivity and specificity of the SF-36 as a screening tool for detecting depressive symptoms.
Results: An MCS score of 35 has a sensitivity of 80% (76-83; 95% confidence interval), a specificity of 90% (87-93), an ROC area of 0.8517 (0.81-0.89), and correctly identified 87% of the sample.
Conclusion: The SF-36 provides the benefits of a general functional health status measure and additionally appears to provide a screening tool for depressive symptoms. A cutoff score of 35 or less on the MCS scale has a high degree of sensitivity and specificity and is able to identify depressive symptoms in patients with back pain, which can help identify patients who will benefit from mental health treatments.