Pain Related to Underdiagnosis of Depression in Primary Care

Lexa W Lee

October 17, 2007 (New Orleans) — Patients with symptoms of physical pain are more likely to be correctly diagnosed as having depression in primary care settings compared with patients without pain, a new study suggests.
The study was presented here at the American Psychiatric Association 59th Institute on Psychiatric Services.Many Go Undiagnosed
Depression is often not recognized and diagnosed in medical patients by providers, although previous studies have shown that pain is correlated with depression, said Kathryn Magruder, PhD, study presenter and associate professor of psychiatry at the Medical University of South Carolina, in Charleston.
In this study, the investigators aimed to determine whether pain is related to the underdiagnosis of depression among primary care patients. To do this, they randomly selected 816 primary care patients from 4 Veterans Administration Medical Centers in the Southwestern United States who were then assessed for major depressive disorder (MDD) and dysthymia using the Mini International Neuropsychiatric Interview (MINI).
The SF-36, a multipurpose self-administered health survey, was used to assess physical pain; medical and psychiatric ICD-9 diagnoses (including MDD, depression, and dysthymia) were verified from medical records for a 24-month period.
Of the total sample, 191 subjects were MINI positive for MDD or dysthymia; these were further divided into 2 groups: 100 who were correctly diagnosed (ICD-9 positive for MDD, dysthymia, or depression not otherwise specified [NOS]), and 91 who were underdiagnosed (ICD-9 negative).
Using Χ2 and logistic regression analyses to compare the 2 groups and adjusting for age, race, and sex, the researchers found that higher self-reported pain on the SF-36 was significantly related to accurate recognition of depression (P = .008). Patients with at least 1 diagnosis related to chest pain (OR, 3.0; 95% CI, 1.3 – 7.0) or neurological pain (OR, 3.5; 95% CI, 1.1 – 11.6) were significantly more likely to be accurately diagnosed for depression.
Other pain-related diagnoses, including back and muscle symptoms, were not significantly related to recognition of depression. Males and minorities were less likely to be recognized as being depressed. Age was not a significant factor. Adjusted data showed self-reported bodily pain to be a stronger predictor of recognition than pain-related diagnoses.
"We found that 47% to 48% of primary care patients who qualified for a diagnosis of depression went unrecognized for the 2-year period by their clinicians," Dr. Magruder told Medscape Psychiatry. "That pretty much corresponds to what we know from the literature. We'd like to look at cost estimates for underdiagnosis of depression and associations with [posttraumatic stress disorder] and generalized anxiety disorder."
Self-Reported Pain Most Significant Factor
The investigators concluded that higher self-reported pain was significantly related to the correct recognition of depression and that certain types of pain, especially chest pain, aided in the recognition of depression. However, males, minorities, and those who report better general health are more likely to be underdiagnosed.
Asked for a comment on this work by Medscape Psychiatry, Tara Strine, an epidemiologist with the Centers for Disease Control and Prevention, in Atlanta, Georgia, said, "While further research is warranted, this is a very encouraging finding, as it indicates that primary care physicians are cognizant of the potential mental as well as physical health components of self-reported pain."
The study was supported by a VA Health Services research and development grant and Eli Lilly. Dr. Magruder and Dr. Strine report no relevant financial relationships.
American Psychiatric Association 59th Institute on Psychiatric Services: Poster 158. Presented October 14, 2007