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Metabolic Comorbidities of Psoriatic Arthritis

Obesity, diabetes, metabolic syndrome and fatty liver disease often strike people with psoriatic arthritis (PsA).

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More than half of people with psoriatic arthritis (PsA) have at least one other medical condition, called a comorbidity. And 40% have three or more comorbid conditions.

The most common comorbidity of PsA is cardiovascular disease (CVD). People with PsA also develop metabolic comorbidities, specifically obesity, diabetes, metabolic syndrome and nonalcoholic fatty liver disease. In addition to raising the risk of CVD, these comorbidities can lead to reduced quality of life, high healthcare costs, more complex PsA treatment and early death.

Managing metabolic conditions will help you better control your PsA, help your medications work better and improve your overall health.

Metabolic Comorbidities

Obesity. As many as 45% of people with PsA are obese. “Obesity rates are much higher in people with PsA than people with rheumatoid arthritis, psoriasis or the general population,” says Lihi Eder, MD, PhD, rheumatologist and scientist at Women’s College Research Institute in Toronto, Canada.

According to Dr. Eder, not only does obesity increase your chance of developing PsA, but it’s also associated with increased disease activity and poorer treatment response.

Metabolic Syndrome. Metabolic syndrome (MetS) is generally defined as having the combination of central obesity (fat around your waist), high blood pressure, insulin resistance and dyslipidemia (high triglycerides, high “bad” cholesterol, low “good” cholesterol).

The percentage of people with PsA who have MetS varies depending on the study. But Alexis Ogdie, MD, a rheumatologist and director of the Penn Psoriatic Arthritis and Spondyloarthropathies Program in Philadelphia, sums it up: “In almost all studies, the prevalence of metabolic syndrome is higher in people with psoriatic arthritis than those with psoriasis or healthy controls.”

People with PsA and MetS tend to have more severe PsA symptoms and a lower likelihood of achieving minimal disease activity.

Diabetes. People with PsA are at a greater risk of developing type 2 diabetes than the general public. Dr. Eder and her team analyzed data collected over a 30-year period of people with PsA; the results were published in 2017 in The Journal of Rheumatology. They found that people with PsA were 43% more likely to develop diabetes than people in the general population.

Even after controlling for obesity, people with PsA still had a higher risk of diabetes. “This tells us that there is another factor related to their disease that’s contributing to their diabetes risk, possibly inflammation,” she explains.

That theory is supported by another finding from her study: PsA patients with greater disease activity were at a higher risk of developing diabetes than those with lower disease activity.

Nonalcoholic fatty liver disease. Nonalcoholic fatty liver disease (NAFLD) is a chronic condition characterized by liver inflammation and excess fat stored in liver cells. It can lead to irreversible liver damage.

NAFLD is seen more often in people with psoriasis than the general population, and Dr. Ogdie says those with PsA have an even higher risk of developing it. According to a 2012 study published in Arthritis Research & Therapy, 28% of PsA patients have fatty liver disease.

Studies show PsA patients with fatty liver disease are unlikely to achieve minimal disease activity, even after adjusting for metabolic syndrome and other characteristics.

Comorbidity Triggers

Why do people with PsA  have these metabolic conditions? Researchers believe there are several possible factors, including inflammation, medications and unhealthy lifestyle choices.

Inflammation. The more severe your systemic inflammation, the more likely you are to have metabolic comorbidities. Dr. Ogdie says that studies support the idea that inflammation – which is known to promote cardiovascular disease – also promotes metabolic abnormalities, insulin resistance and diabetes. Obesity contributes to inflammation, too. “Fat tissue is considered an endocrine organ that produces a variety of inflammatory chemicals and can add to your overall level of systemic inflammation,” says Dr. Ogdie.

Medications. Some medications used to treat psoriasis and psoriatic arthritis may increase your risk for or worsen existing metabolic comorbidities.

Corticosteroids can lead to weight gain, elevated blood sugar levels and changes in cholesterol profile. NSAIDs can increase your blood pressure and your risk of cardiovascular events. Leflunomide is associated with elevated blood pressure; retinoids can affect cholesterol; and methotrexate and leflunomide can affect liver function.

“Every time we prescribe these medications, we need to monitor for potential side effects and weigh the benefits versus the potential risks,” says Dr. Eder.

Lifestyle. Exercising may be the last thing on your mind when you’re itchy and in pain. And you may crave comfort food instead of more nutritious options. But allowing occasional treats and skipped workouts to become habits can lead to metabolic conditions.

Managing Weight and Inflammation

If you are overweight, losing weight will decrease your risk for developing diseases like diabetes, fatty liver disease and cardiovascular disease. It may also make your psoriatic arthritis treatments work better.

According to a 2014 study published in Annals of the Rheumatic Diseases, PsA patients who lost at least 5% of their body weight had nearly a four-times higher rate of achieving minimum disease activity than those who didn’t lose weight. Patients who lost 10% of their body weight had a more than a six-times greater likelihood of achieving that status.

Because inflammation increases your comorbidity risks, work with your rheumatologist and dermatologist to minimize disease activity.

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