In his Rheumatology Research Foundation Philip Hench, MD, Memorial Lecture Sunday, Christopher T. Ritchlin, MD, MPH, presented extensive research suggesting that psoriasis and psoriatic arthritis (PsA) are linked but distinct rheumatologic disorders that require early diagnosis and early intervention to improve clinical outcomes.
Dr. Ritchlin, Professor of Medicine, Chief of Allergy/Immunology and Rheumatology, and Director of the Translational Immunology Research Center at the University of Rochester Medical Center, talked about what he sees as the shared disease pathways and mechanisms between the two disorders that could open new avenues for more effective diagnosis and treatment of PsA.
“These are linked but distinct disorders, and key events in the skin are integral to what happens downstream in the joint,” he said. “In preclinical PsA patients, there is tremendous opportunity for early intervention. This is a special population we can identify by phenotype in psoriasis patients. We know that about 20 to 30 percent of them are going to develop psoriatic arthritis. We can use this population to learn biology and, most important, to improve outcomes.”
To improve outcomes in PsA patients, Dr. Ritchlin recommended early diagnosis of psoriasis and more aggressive treatment of psoriasis patients, including systemic therapy for patients with arthritis biomarkers, perhaps combining oral agents with biologics or even phototherapy to prevent the onset of PsA.
“I really think that combination therapies may be required with psoriatic arthritis. These could be biologic combinations in low doses, or cycled, or using bi-typical antibodies. I think that the complexity of events in psoriatic arthritis patients requires a new way of thinking about treating this disease,” he said.
Research has shown that the risk factors for PsA in psoriasis patients include nail dystrophy, rubella vaccination, injury, trauma, fractures, obesity, severe psoriasis, and psoriasis of the scalp, intergluteal region, or perineum.
He recommended lifestyle modifications for psoriasis patients.
“We have huge issues with our psoriasis patients — obesity, hypercholesterolemia, and other issues we need to be addressing or they are not going to get better no matter what other treatment we offer.”
Bone scans have shown that psoriasis patients have subclinical bone and entheseal inflammation. MRI studies have demonstrated some psoriasis patients have bone edema, synovitis, or erosions. Ultrasound studies have shown that a significant percent of psoriasis patients have abnormalities in the enthesis.
“A large number of these patients have subterranean joint issues going on that are not clinically manifested. An important question is: Can we use imaging tools to cull out patients with psoriasis that may be at risk for PsA and may need treatment now?” Dr. Ritchlin said.
Patients may make the transition from psoriasis to PsA in many different ways. Some patients develop psoriasis, tenosynovitis, and enthesitis. They receive treatment symptomatically, go away, and don’t come back.
“We have to be careful about labeling them with psoriatic arthritis. I think they need to have symptoms sustained for three months or longer before we make this diagnosis,” he said.
Dr. Ritchlin cited a study published in 2014 in the New England Journal of Medicine indicating that a better understanding of the immunopathogenesis of psoriasis has led to the development of multiple biologic drugs targeting specific molecules that are essential for the development of psoriatic plaques.
The study supported the use of interleukin-17RA as a viable target for the treatment of psoriasis. Patients given brodalumab, a human, anti-interleukin-17RA monoclonal antibody that antagonizes the interleukin-17 pathway, had significantly greater improvements in PASI (Psoriasis Area and Severity Index) score compared with the placebo group.