Patients should be aware that psoriasis has health impacts beyond the skin alone.
People with chronic inflammatory disorders like psoriasis and rheumatoid arthritis may have an increased risk of developing serious liver damage, a recent study suggests.
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 conditions like psoriasis or rheumatoid arthritis - and taking methotrexate - influenced the odds of developing serious liver disorders.
Compared to 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 to patients without psoriasis and those with diseases such as rheumatoid arthritis which are treated with similar medications,” said senior study author Dr. Joel Gelfand of the University of Pennsylvania Perelman School of Medicine in Philadelphia.
“Medications which 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 said 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 November 2 in the Journal of Investigative Dermatology.
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 rheumatoid arthritis.
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 rheumatoid arthritis.
Independent of 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.
Pfizer, which sells a version of methotrexate, has hired Gelfand and another study author as consultants and given them research grants, although the drugmaker wasn’t involved in the design or analysis of the current study. The authors have other financial ties to several other drug companies.
One limitation of the study is that researchers didn’t look at deaths from liver disease. Another drawback is that they lacked data on whether people at risk for liver disease might have been steered away from methotrexate to other therapies.
Even so, the findings add to evidence that patients need to consider the liver risks associated with these disorders, said Dr. Lawrence Eichenfield, a researcher at the University of California, San Diego, who wasn’t involved in the study.
“Patients should be aware that psoriasis has health impacts beyond the skin alone, and its management should be considered as an important part of the health of an individual,” Eichenfield said by email. “Liver function tests should be tested in psoriasis patients and the results may influence choices for therapy.”
An alternative treatment for joint pain, non-steroidal anti-inflammatory drugs (NSAIDs), also carry a risk of liver disease, cautioned Dr. Alexander Egeberg, a researcher at the University of Copenhagen who wasn’t involved in the study.
“Consequently, physicians should carefully weigh the risks and benefits of NSAIDs as well as methotrexate when treating patients with inflammatory diseases,” Egeberg said by email.