Low socioeconomic status increases depression risk in rheumatoid arthritis patients

Study findings are reported in the February issue of Arthritis Care & Research, a journal published by Wiley-Blackwell on behalf of the American College of Rheumatology (ACR).

Roughly 1.3 million Americans are affected by RA -- a chronic autoimmune disease that can cause functional limitations and may lead to physical disability in many patients. Prior studies have shown that depression is common, occurring in 13% to 42% of RA patients and is associated with worse outcomes, including greater risk of heart attack, suicide, and death. In the U.S., socioeconomic position as measured by race, gender, age, income, education and health access has significant impact on overall health.

Mary Margaretten, M.D., from the Arthritis Research Group at the University of California, San Francisco (UCSF) and lead study author explained, "We assessed the extent to which low SES influences the relationship between disability and depression in order to better identify those patients at higher risk for depression." Researchers used data obtained from the UCSF RA cohort in which participants were enrolled from an urban county, public hospital that serves the poor and a referral, tertiary-care medical center. The data included 824 visits for 466 patients, 223 from the public hospital and 243 from the tertiary-care clinic.

Analysis showed that 37% of participants had moderate to severe depression, scoring 10 or higher on the Patient Health Questionnaire (PHQ-9). The mean Health Assessment Questionnaire (HAQ) score was 1.2 and the disease activity score (DAS28) was 4, indicating fairly high levels of functional impairment and disease activity, respectively. Researchers also found significant differences between depressed and non-depressed patients related to race, public versus university hospital, functional limitation and disease modifying anti-rheumatic drug (DMARD) treatment. Differences in depression severity were not impacted by gender, age, disease duration, steroid use and dose, or biologic therapy.

Furthermore, the team found that county hospital patients also had significantly higher depression scores (PHQ-9 of 7.3) than patients at the university medical center (PHQ-9 of 5.7). An interaction existed between socioeconomic status and disability such that the association of functional limitation with depression scores was stronger for patients at the public hospital clinic compared to those at the tertiary-care clinic.

Dr. Margaretten concluded, "For the same level of disability, patients with low SES may be more likely to experience depression. Detection and documentation of the differing effects of disability on depression between patients of different socioeconomic status can help rheumatologists improve health outcomes by initiating appropriate and timely treatment for depression."