In January, researchers from France and Australia demonstrated that individuals with inflammatory bowel disease (IBD) were at an increased risk for skin cancer, particularly those who were currently taking or had taken thiopurines, a class of immunosuppressants that are frequently prescribed for IBD. Now, in a series of two studies that demonstrate another link between IBD and common skin conditions, researchers from several institutions in Boston have demonstrated that patients with psoriasis are at an increased risk for IBD.
In the first study, first author Wenqing Li, PhD, of the department of dermatology at Brigham and Women’s Hospital, and colleagues examined 174,646 patients who had psoriasis at the time of enrollment who then developed IBD. Specifically, 187 incident cases of Crohn’s disease (CD) and 236 incident cases of ulcerative colitis (UC) occurred during follow-up; the risk of CD associated with psoriasis was significantly increased, but the association with UC was not significant. The researchers also performed a combined analysis of both cohorts, which revealed that psoriasis cases experienced a significantly increased risk of CD (combined relative risk [RR] 3.91, 95% confidence interval [CI]: 2.26-6.76) but not UC (combined RR 1.23, 95% CI: 0.46-3.33).
According to the researchers, “in fully adjusted analyses, psoriasis patients had about a four-fold greater incidence of Crohn’s disease,” and study patients with concomitant psoriasis and psoriatic arthritis had almost a seven-fold higher likelihood of developing Crohn’s disease during follow-up.
The second study examined patients at an IBD clinic who were asked to fill out the Psoriasis Screening Tool (PST) for undiagnosed psoriasis. Among 147 patients, psoriasis was identified in 12.9% in all individuals, 13.4% with CD and 12.9% with UC. The PST also revealed nine cases of psoriasis that had not been previously documented in the patients’ charts.
Eva Mihalis, the first author on the second study who is with Harvard Medical School, explains that the prevalence of psoriasis in the IBD patients in the study was four to six times higher than the estimated prevalence for the general population, which ranges from 2% to 3%.
Dr. Abrar Qureshi, an associate physician at Brigham and Women’s and an associate professor of dermatology at Harvard Medical School, led both studies. Results of both investigations were presented at the 2012 Society for Investigative Dermatology Meeting, held in Raleigh, NC, at the beginning of this month. To access the abstracts of both presentations, please visit https://www.sidnet.org/annualmeeting.aspx.
