Psoriatic Arthritis & the Obese Patient

Estimates from the National Psoriasis Foundation indicate that more than 8 million people in the U.S. suffer from psoriasis and that approximately 30% of those individuals develop psoriatic arthritis (PsA).¹ Given these statistics, roughly 2.4 million people in the country are likely affected by PsA. Moreover, patients with this systemic condition carry a higher-than-average burden of cardiometabolic comorbidities, such as diabetes, hypertension, cardiovascular disease—and obesity.

“Obesity is one of the stronger risk factors for development of psoriatic arthritis, along with severe psoriasis, history of joint trauma, family history and general inflammatory bowel disease,” says Alexis Ogdie, MD, MSCE, rheumatologist and associate professor of medicine and epidemiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, and director of the Penn Psoriatic Arthritis and Spondyloarthritis Program.

Dr. Ogdie estimates that approximately 50% of patients with PsA in the U.S. have a body mass index (BMI) of more than 30, a percentage exceeding that of the entire nation’s general population by just 9%, according to currently available statistics from the Centers for Disease Control and Prevention.² The overall trend toward a more obese populace is expected to continue, and, thus, rheumatologists can expect the number of patients they see with PsA who also are obese to rise as well.

The relationship between PsA and obesity is complex and possibly bidirectional in nature. It has been theorized that the chronic systemic inflammation that characterizes obesity is not only caused by the excess weight but may be a risk factor for it.³ This is one of many reasons treatment management for patients affected by both PsA and obesity is particularly challenging for the rheumatologists and rheumatology professionals who work with them. Many are exploring new ways to approach and care for these patients.

The Weight Factor

Given the progressive nature of PsA, the earlier the disease can be diagnosed the better the long-term treatment outcome, says Dr. Ogdie. However, any diagnosis of PsA can take time, as undiagnosed patients generally first go to their primary care doctor, who might find inflammatory conditions that point to PsA. “Having uveitis or inflammatory bowel disease, for example, might elevate the likelihood that the patient’s joint complaints are psoriatic arthritis, and speed up diagnosis,” Dr. Ogdie notes.

However, an obese patient, particularly one without any of these telltale inflammatory conditions, can be especially difficult to diagnose, according to Dr. Ogdie. “People with obesity have a higher prevalence of osteoarthritis, so this can be hard to separate out—are these symptoms of osteoarthritis, is this mechanical in general, or is it psoriatic arthritis?” she says. “Patients with obesity have a higher prevalence of fibromyalgia and that’s also sometimes difficult to distinguish from PsA.”