These inflammatory disorders are often treated with methotrexate, a medication linked to an increased risk of liver disease. For the current study, researchers followed more than 1 million people for an average of six years to see how having such conditions as psoriasis or RA—and taking methotrexate—influenced the odds of developing serious liver disorders.
Compared with people without chronic inflammatory diseases, people with psoriasis were 37% more likely to develop liver disorders. When psoriasis patients took methotrexate, they had roughly twice the odds of liver damage.
With psoriatic arthritis, the increased risk of liver disease was 38% without drug therapy and 67% with methotrexate. For rheumatoid arthritis, there was no increased risk of liver disease when people took methotrexate, but when they didn’t they had 49% higher odds of liver damage.
“This study is the first, to our knowledge, to empirically support the long held belief that psoriasis patients are more prone to serious liver problems compared with patients without psoriasis and those with diseases, such as rheumatoid arthritis, who are treated with similar medications,” says senior study author Dr. Joel Gelfand of the University of Pennsylvania Perelman School of Medicine in Philadelphia.
“Medications that are toxic to the liver, such as methotrexate, should be used cautiously in patients with psoriatic disease, especially those with additional risk factors such as obesity or regular alcohol use,” Gelfand says by email.
The study suggests systemic inflammation, which is present in all three diseases, may play a significant role in development of liver disease, particularly in those with psoriasis, researchers note online Nov. 2 in the Journal of Investigative Dermatology.1
For the study, researchers examined data on almost 1.3 million people without chronic inflammatory disorders, as well as roughly 198,000 psoriasis patients, 12,000 people with psoriatic arthritis and 54,000 with RA.
Among people with inflammatory disorders who took systemic therapy—medications that reach the whole body—methotrexate was the most commonly prescribed option.
Overall, 6% of psoriasis patients were prescribed systemic therapy, as were 53% of people with psoriatic arthritis and 61% of people with RA.
For independent risk factors commonly seen in liver disease, such as alcohol use and diabetes, the study found that patients with psoriatic skin or joint disease, particularly patients with more severe skin psoriasis, had an elevated risk for serious liver disease.