Psoriatic arthritis is a complex disease that mainly affects the joints but that can also cause problems in other parts of the body. Over time, the persistent inflammation may begin to affect the eyes, bones, heart, and liver, and increase the risk of gout, depression, diabetes, and cancer. The widespread effects that are associated with psoriatic arthritis may seem disconnected from what you’re experiencing as the result of your disease right now, but their reality underscores the importance of getting adequate treatment for your psoriatic arthritis.
The risk of health effects may be reduced if this autoimmune disorder is diagnosed and treated early.
The following list includes associated comorbid conditions, extra-articular manifestations, and complications of psoriatic arthritis that you should know about.
Uveitis
Uveitis is an extra-articular manifestation of psoriatic arthritis. According to a 2012 review in the Annals of Brazilian Dermatology, around 7% of people with psoriatic arthritis develop uveitis, leading to eye redness, swelling, blurring, and floaters.
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Uveitis is closely linked to blepharitis (eyelid inflammation), a condition caused when psoriatic plaques alter the shape of the eyelid. This can lead to eye dryness and irritation as eyelashes scrape against the eyeball. Both of these symptoms can contribute to the development of uveitis.
Obesity
Obesity occurs at a higher rate in people with psoriatic arthritis (27.6%) than the general population (22%). The risk is especially high in those with spinal involvement.
A 2010 study in the Archives of Dermatology showed that obesity before the age of 18 increases the risk of psoriatic arthritis and leads to the earlier onset of joint symptoms.
Inflammation affects blood sugar and metabolism and losing weight may help reduce the risk of psoriatic arthritis. If you already have the disease, attaining a healthy weight may help reduce the frequency or severity of acute flares.
Metabolic Syndrome
Metabolic syndrome is a cluster of conditions that includes high blood pressure, high blood sugar, excess fat around the waist, and abnormal cholesterol levels. Having psoriatic arthritis jumps your risk of metabolic syndrome from 23% to 44%.
Psoriatic inflammation is believed to have a twofold effect on the body. On the one hand, it makes it harder to control blood sugar and blood pressure. On the other, it increases inflammatory proteins called cytokines that alter insulin sensitivity and increase “bad” LDL cholesterol levels. All of these things contribute to weight gain and obesity.
Older age and worsening psoriatic arthritis symptoms are associated with an increased risk of metabolic syndrome. In contrast, the length of time a person has psoriatic arthritis does not affect the risk.
Type 2 Diabetes
Psoriatic arthritis is closely linked to type 2 diabetes. According to a 2013 review in JAMA Dermatology, mild psoriatic arthritis increases the risk of diabetes by 53%, while severe psoriatic arthritis nearly doubles the risk.
This phenomenon can be explained, in part, by the impact metabolic syndrome has on blood sugar. Metabolic syndrome is known to reduce insulin sensitivity (the ability to absorb sugar from the bloodstream). On top of that, long-term inflammation can undermine pancreatic function, reducing the amount of insulin that it produces.
Early, effective treatment of psoriatic arthritis may reduce the risk of diabetes irrespective of all other factors.
Cardiovascular Disease
Heart disease, already a concern with many older adults, is all the more worrisome in people with psoriatic arthritis. According to a 2016 study in Arthritis Care & Research, psoriatic arthritis increases the risk of cardiovascular disease by 43% compared to the general population.
This is partly due to the high incidence of metabolic syndrome in people with psoriatic arthritis, but other factors also contribute. Chief among these is the effect that chronic inflammation has on blood vessels, causing arterial walls to stiffen and narrow. This increases the risk of atherosclerosis, heart attack, and stroke. The risk is highest in people over 70.
Osteoporosis
There is a close connection between osteoporosis and psoriatic arthritis, particularly in postmenopausal women who are already at an increased risk of bone loss. Though psoriatic inflammation is believed to accelerate bone loss, other factors may contribute.
For example, joint pain and stiffness can lead to physical inactivity and weight gain, the latter of which amplifies inflammation. The use of corticosteroid drugs can inhibit bone growth, and nutritional deficits can lead to calcium and vitamin D deficiencies, causing bone thinning. Bone fractures are especially common in older women with psoriatic disease.
A 2015 study in Osteoporosis International concluded that psoriatic arthritis increases the porosity of cortical bone (the outer surface of bones).
Inflammatory Bowel Disease
As an autoimmune disease, psoriatic arthritis is characterized by immune dysfunction. Inflammatory bowel disease (IBD) is a group of intestinal disorders believed to have autoimmune characteristics.
In recent years, scientists have found a close link between psoriatic arthritis and IBD, specifically Crohn’s disease and ulcerative colitis. A comprehensive 2018 review published in JAMA Dermatology concluded that psoriatic arthritis was associated with a 1.7-fold increased risk of ulcerative colitis and a 2.5-fold increased risk of Crohn’s disease.
The cause for this link is not entirely clear, although each of the three diseases is characterized by chronic inflammation. It has been suggested that psoriatic arthritis and Crohn’s disease have similar genetic characteristics.
Metabolic Dysfunction-associated Steatotic Liver Disease
The liver is frequently impacted by inflammation from psoriatic arthritis, especially in people with obesity, type 2 diabetes, high cholesterol, and insulin resistance. This translates to an increased risk of metabolic dysfunction-associated steatotic liver disease (MASLD, formerly known as nonalcoholic fatty liver disease or NAFLD).
According to a 2015 study from George Washington University, the risk of MASLD is 1.5 times greater in people with psoriatic disease than people without. With that said, it is unclear if the two diseases are linked by psoriatic inflammation or if metabolic syndrome, common with both conditions, is the ultimate cause.
People with untreated psoriatic arthritis and MASLD have worse joint symptoms and a higher degree of fibrosis (liver scarring).
Cancer
Although it is unclear how psoriatic arthritis contributes to the development of cancer, researchers have found patterns in how certain autoimmune diseases increase the risk of blood and/or solid tumor malignancies.
According to a 2016 study published in Clinical Rheumatology:
- Psoriatic arthritis is closely linked to leukemia, lymphoma, and breast cancer.
- Psoriasis is closely associated with leukemia, lymphoma, and non-melanoma skin cancers.
- Rheumatoid arthritis is closely linked to both lymphoma and lung cancer.
Scientists have several theories as to why this occurs. For one, the systemic inflammation caused by these autoimmune disorders places stress on blood cells, increasing the risk of blood cancers like leukemia or lymphoma.
Others contend that each disease has its own type of inflammation. Autoimmune cells and autoantibodies trigger alterations in inflammatory proteins, including tumor necrosis factor (TNF) and interleukin. Some of these may damage the DNA of skin cells, while others may cause harm to lung cells. This could explain why the risk of breast cancer is high with psoriatic arthritis, but not with psoriasis or rheumatoid arthritis.
People with psoriatic arthritis have a 64% increased risk of cancer compared to the general population. However, if the disease is properly controlled, there is no statistical difference in the risk of cancer.
