Psoriasis patients who also have major depressive disorder (MDD) might be at risk of developing psoriatic arthritis, compared with psoriasis patients without MDD, according to findings published in the Journal of Investigative Dermatology (Apr. 2017; 137(4):828–835).
“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 senior investigator Dr. Cheryl Barnabe, associate professor, Departments of Medicine and Community Health Sciences, rheumatologist, Alberta Health Services at the University of Calgary.
What leads to PsA?
“We already know that people with psoriasis are at risk for developing psoriatic arthritis, but not every psoriasis patient ends up with psoriatic arthritis,” said the lead author of the study, Ryan Lewinson. “There is not a lot known about what might be contributing to the development of psoriatic arthritis in people with psoriasis.”
Lewinson is a PhD candidate in biomedical engineering and is concurrently pursuing his studies to obtain his doctor of medicine designation through the Leaders in Medicine MD/ PhD program at the University of Calgary.
The objective of this population-based study, according to the study authors, was to evaluate clinical data to elucidate the possible role of MDD in the progression of inflammatory disease from one organ system (the skin) to involving multiple organ systems, and thereby highlight a possible risk factor for psoriatic arthritis development among patients with psoriasis.
At increased risk of PsA
During this investigation, the researchers evaluated data obtained from The Health Improvement Network (THIN), a primary medical records database in the United Kingdom, to identify 73,447 individuals with psoriasis. According to the authors, patients were followed for up to 25 years until the development of the primary outcome of psoriatic arthritis or the censor date of the study.
Data from the statistical analysis showed that patients with psoriasis who developed MDD were at an increased risk of subsequently developing psoriatic arthritis compared with patients who did not develop MDD, even after accounting for numerous covariates (hazard ratio 1.37, 95% confidence interval 1.05–1.80,p=0.021). This result was maintained through numerous sensitivity analyses, the study authors wrote.
“The main finding is that even after we controlled for a number of different factors that could be associated with both depression and psoriatic arthritis, we found that psoriatic patients still have a 37 per cent increased risk of developing psoriatic arthritis if they first develop depression,” indicated Dr. Barnabe.
These data support the hypothesis that MDD increases the risk of developing psoriatic arthritis among patients with psoriasis, suggesting a need for heightened prevention and management of MDD in patients with psoriasis, they said.
“In the area of mental health and epidemiology research, investigators at the University of Calgary have established expertise in assessing the association between mental health and chronic inflammatory diseases,” Lewinson said. “This collaboration allowed us to gain important insight into the development of 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 Dr. Scott Patten, of the O’Brien Institute for Public Health, Hotchkiss Brain Institute and Mathison Centre for Mental Health Research and Education, psychiatrist and professor of epidemiology, Cumming School of Medicine at the 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, according to Dr. Patten, who was quoted in a press release.
Causality not yet proven
This investigation is considered an association study, noted Dr. Barnabe, who explained that they have not yet proven causality.
“We encourage more people to conduct additional research to help prove the cause and effect of this association,” she added.
“I think in the future, it would be good to look at what is contributing toward this associated risk and how does it relate to what we know about psoriasis already,” Lewinson said.
“The take-home message of this study is if you treat people who have psoriasis then it is important to screen for depression and to keep in mind that these patients might have an increased chance of developing psoriatic arthritis,” Lewinson told THE CHRONICLE.
Dr. Barnabe added: “We hope that our research will heighten awareness about the possibility of an association between psoriasis, depression and psoriatic arthritis—if we could prevent that progression for some patients, then that would be amazing.”
This study raises important questions regarding the potential role of systemic inflammation, which is also elevated in depression, in driving a disease phenotype, which needs to be confirmed in clinical cohorts, Dr. Barnabe said in conclusion.
The investigators noted that the study was supported by CIHR-LEO Studentship in Psoriasis Disease through the Canadian Association of Psoriasis Patients.