Metabolic Comorbidities of PsA

More than half of people with psoriatic arthritis (PsA) have at least one other related medical condition, or "comorbidity," and 40% of people with PsA have three or more comorbid conditions. Understanding and managing these conditions can help you better control your PsA and maximize the effectiveness of your medications, and it can improve your overall health.

In many cases, people with PsA develop metabolic comorbidities — specifically obesity, diabetes, metabolic syndrome and non-alcoholic fatty liver disease — all of which raise the risk of cardiovascular disease (CVD), the most common PsA comorbidity. In addition, these conditions can lead to lower quality of life, high healthcare costs, more complex PsA treatment and early death.

Obesity. As many as 45% of people with PsA are obese — a far higher rate than in people living with rheumatoid arthritis, psoriasis or the general population. Not only does obesity increase the chance of developing PsA, but it’s also associated with increased disease activity and poorer treatment response.

Metabolic Syndrome. Metabolic syndrome is the combination of central obesity (fat around your waist), high blood pressure, insulin resistance and dyslipidemia (high triglycerides, high LDL “bad” cholesterol and low HDL “good” cholesterol). The percentage of people with PsA who have metabolic syndrome varies by research study; however, in almost all studies, the frequency of metabolic syndrome is higher in people with psoriatic arthritis than in those with psoriasis or in healthy control groups. People with PsA and metabolic syndrome tend to have more severe PsA symptoms and less likelihood of achieving minimal disease activity.

Diabetes. People with PsA are at a greater risk of developing type 2 diabetes than the general public. In a 30-year study published in 2017 in The Journal of Rheumatology researchers found that people with PsA were 43% more likely to develop diabetes than people in the general population. Even after researchers controlled for obesity, they found that people with PsA still had a higher risk of diabetes. This could mean another factor related to their disease is contributing to their risk, possibly inflammation. Another finding from the study supports that theory: 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, which can lead to irreversible liver damage. NAFLD is seen more often in people with psoriasis than in the general population, and according to one study, 28% of PsA patients have fatty liver disease. Studies show these patients are unlikely to achieve minimal PsA disease activity, even after adjusting for metabolic syndrome and other characteristics.

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. Studies support the idea that inflammation — which is known to promote CVD —-- also promotes metabolic abnormalities, insulin resistance and diabetes. Obesity contributes to inflammation, too. Fat tissue produces a variety of inflammatory chemicals and can add to your overall level of systemic inflammation.
• Medications. Some medications used to treat psoriasis and psoriatic arthritis may increase your risk for developing metabolic comorbidities 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. When taking these drugs, doctors should monitor you for side effects and help weigh the benefits and risks. 
• 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.

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