Optimal SF-36 Threshold to Screen for MDD, GAD in RA

The Short-Form Health Survey (SF-36) can be used to effectively determine the presence of major depressive disorder (MDD) and generalized anxiety disorder (GAD) in patients with rheumatoid arthritis (RA). The use of a threshold of ≤38 on the mental component summary may most optimally screen for the presence of depression or anxiety.  

Faith Matcham, from the Department of Psychological Medicine at the Institute of Psychiatry, Psychology, and Neuroscience at King’s College in London, United Kingdom, and colleagues conducted an analysis of the SF-36 survey to assess its accuracy in identifying the presence of probable MDD or GAD in patients with RA. The findings of the analysis were published in BMC Musculoskeletal Disorders.

“The SF-36 has been extensively validated as a measure of QoL [quality of life] in multiple populations and is the most widely used and evaluated QoL outcome measure,” the authors explained. “The SF-36 consists of 8 domains, which assess physical function, role physical, bodily pain, global health, vitality, social function, role emotional and mental health.”

The researchers collected SF-36 data from 100 patients with RA treated as outpatients. They compared mental health subscale and mental component summary scores against depression and anxiety data collected using validated measures. They also used area under the curve to compare the performance of the SF-36 components to the 9-item Patient Health Questionnaire for depression and the 7-item GAD questionnaire for anxiety.

The results showed that a mental health subscale with a threshold ≤52 had sensitivity of 81.0% and specificity of 71.4% to detect anxiety, and correctly classified 73.5% of patients with probable GAD.

A threshold ≤56 had sensitivity of 92.6% and specificity of 73.2% to detect depression, and correctly classified 78.6% of patients. The same threshold could also be used to detect either depression or anxiety with sensitivity 87.9%, specificity of 76.9%, and accuracy of 80.6%.

When researchers analyzed the mental component scores, they found that a threshold ≤35 had sensitivity of 85.7% and a specificity of 81.9% to detect anxiety, and correctly classified 82.8% of patients with probable GAD. A threshold ≤40 had sensitivity of 92.3% and specificity of 70.2% to detect depression, correctly classifying 76.3% of patients.

Finally, the researchers noted that a mental component score with a threshold ≤38 could be used to detect either depression or anxiety with sensitivity of 87.5%, specificity of 80.3%, and accuracy of 82.8%.

Summary and Clinical Applicability

The analysis found that the SF-36 survey was an effective diagnostic tool for MDD and GAD in patients with RA. Utilizing a threshold of ≤38 on the mental component summary appears to most optimally identify patients with psychological disease comorbidity.

“The addition of regular [quality of life hazard ratio] HRQoL measurement to routine RA clinical care would be beneficial, as QoL is a key outcome of importance to patients, and doing so would also support the need for embedded mental health care within rheumatological management practice,” the authors concluded.

Limitations and Disclosures

• The researchers noted that there was a lack of a “gold-standard” measure of depression to validate the SF-36 domains, as the participants were not diagnosed by a psychologist or psychiatrist
• Patients who were unable to give consent because of learning disabilities or dementia were not included in the study, which excluded many older patients with higher levels of pain or disability

Reference

Matcham F, Norton S, Steer S, Hotopf. Usefulness of the SF-36 health survey in screening for depressive and anxiety disorders in rheumatoid arthritis. BMC Musculoskeletal Disorders. 2016; doi: 10.1186/s12891-016-1083-y.