Among persons with psoriasis, those who reported being obese at age 18 had an increased risk of developing psoriatic arthritis, according to a report in the July 19 issue of Archives of Dermatology, one of the JAMA/Archives journals.1
Psoriatic arthritis is a specific type of arthritis that develops in the joints of some patients who have psoriasis. According to background information in the article, “obesity has emerged as a significant risk factor for psoriasis,” and “psoriatic arthritis affects 6 percent to 42 percent of people with psoriasis.” Additionally, “psoriatic arthritis shares some clinical features with rheumatoid arthritis, both leading to joint destruction and significant morbidity.”
Razieh Soltani-Arabshahi, M.D., of the University of Utah School of Medicine, Salt Lake City, and colleagues studied a volunteer sample of patients with dermatologist-diagnosed psoriasis enrolled in the Utah Psoriasis Initiative from November 2002 to October 2008. Of the 943 participants, 50.2 percent were women and psoriatic arthritis was present in 26.5 percent of participants with psoriasis (250 persons).
The study found that body mass index (BMI) at age 18 was predictive of psoriatic arthritis. Other predictors included younger age at psoriasis onset, being female and having larger body surface areas affected with psoriasis. Additionally, the findings show “the obese group having an earlier onset of psoriatic arthritis, followed by the overweight group and finally the normal BMI group.” Twenty percent of the overweight or obese group developed psoriatic arthritis by age 35 years while 20 percent of those individuals in the normal BMI group developed psoriatic arthritis by age 48.
The authors conclude that their findings, “support a growing concept that patients more prone to psoriatic arthritis might benefit from more frequent and meticulous screening measures for early detection and treatment of psoriatic arthritis, i.e., before the development of irreversible joint destruction.”
“In most patients with psoriatic arthritis, the symptoms do not develop until years after the onset of cutaneous psoriasis,” write Alexis Ogdie, M.D., and Joel M. Gelfand, M.D., M.S.C.E, of the University of Pennsylvania Hospital, Philadelphia, in an accompanying editorial2. “As a result, patients with psoriasis represent a unique opportunity to identify individuals at very high risk of developing a chronic inflammatory arthropathy (i.e. psoriatic arthritis). To determine which patients with psoriasis are at greatest risk of developing psoriatic arthritis, it is essential that risk factors be identified using robust epidemiologic approaches.”
“With the exception of severity of skin psoriasis, the existing studies of risk factors for psoriatic arthritis have yielded generally inconsistent findings,” the authors write. Additionally, “epidemiologic studies evaluating risk factors for psoriatic disease did not start until very recently, and very few environmental risk factors (such as obesity and smoking for psoriasis) have been identified and confirmed in more than one study.”
“Using data accrued in the coming years, future risk factor studies might overcome the methodologic challenges of previous investigations, and we eagerly await the results. Ultimately, identification of risk factors for psoriatic arthritis holds the promise of improving our ability to diagnose this condition and prevent it through risk-factor modification.”
1. Arch Dermatol. 2010;146:721-726.
2. Arch Dermatol. 2010;164:785-788.