Patients with psoriasis who developed depression were at a 37% greater risk of subsequently developing psoriatic arthritis, compared with patients with psoriasis who did not develop depression, according to a study published in the Journal of Investigative Dermatology.
"For many years, the rheumatology and dermatology communities have been trying to understand which patients with psoriasis go on to develop psoriatic arthritis and how we might detect it earlier in the disease course," explained Cheryl Barnabe, MD, McCaig Institute for Bone and Joint Health, University of Calgary, Calgary, Alberta.
Depression is common among patients with psoriasis. Based on recent laboratory work demonstrating that major depressive disorder is associated with increased systemic inflammation, the researchers hypothesised that patients with psoriasis who develop depression are at increased risk of subsequently developing psoriatic arthritis.
Using the Health Improvement Network (THIN) -- a primary care medical records database in the United Kingdom -- the researchers identified over 70,000 patients with a new diagnosis of psoriasis. Through follow-up records, they identified individuals who subsequently developed depression and those who developed psoriatic arthritis. Patients were followed for up to 25 years or until they developed psoriatic arthritis.
Statistical analysis showed that patients with psoriasis who developed major depressive disorder were at 37% greater risk of subsequently developing psoriatic arthritis compared with patients who did not develop depression, even after accounting for numerous other factors such as age and use of alcohol.
The study highlights the need for physicians to manage patients with psoriasis to identify and address depression. This could include rapid, effective treatment of psoriasis and psychosocial management of the cosmetic burden of psoriasis.
The study also draws into question the biological mechanisms by which depression increases the risk for developing psoriatic arthritis. These mechanisms may include altered systemic inflammation as a consequence of depression, or even the role of lifestyle behaviours such as physical activity or nutrition, which are typically worsened by depression, and which may place an individual at risk for psoriatic arthritis.
"There is a tendency to think of depression as a purely 'psychological' or 'emotional' issue, but it also has physical effects and changes in inflammatory and immune markers have been reported in depressed people," commented Scott Patten, MD, Cumming School of Medicine, University of Calgary. "Depression may be a risk factor for a variety of chronic conditions and this research is an example of how big data approaches can identify these associations."
"This study raises important questions on the role of systemic inflammation, which is also elevated in depression, in driving a disease phenotype, which needs to be confirmed in clinical cohorts," said Dr. Barnabe.
SOURCE: Elsevier Health Sciences
