MAUI, HAWAII (FRONTLINE MEDICAL NEWS) – Two recent Scandinavian studies highlight the considerable room for improvement that exists in psoriatic arthritis outcomes, according to speakers at the 2018 Rheumatology Winter Clinical Symposium.

“We’re not doing so well. I think that in general, if you think of the treatments that we have and the treat-to-target approach, psoriatic arthritis lags behind rheumatoid arthritis, maybe by a decade,” declared Arthur Kavanaugh, MD , program director for the symposium and professor of medicine at the University of California, San Diego.

He was a coauthor of a Norwegian cross-sectional study of 141 psoriatic arthritis patients assessed during 2013-2014 by investigators who used an array of disease activity measures. Among the findings: The group’s median Disease Activity index for PSoriatic Arthritis ( DAPSA ) score was 14.5, the Disease Activity Score for 28 joints using erythrocyte sedimentation rate was 3.2, and – most tellingly – only 22.9% of them fulfilled the criteria for minimal disease activity (MDA), which requires very low or no activity in five of seven domains of psoriatic arthritis. Moreover, 42 patients weren’t on any disease-modifying antirheumatic drugs whatsoever ( J Rheumatol. 2017 Apr;44[4]:431-6 ).

“If you say that MDA is remission, a 23% remission rate is not good enough. And there are some people who are not on treatment. So I think we’re still seeing a lag in psoriatic arthritis. We’re not treating it as aggressively as we are rheumatoid arthritis,” said Dr. Kavanaugh, director of the Center for Innovative Therapy in the university’s division of rheumatology, allergy, and immunology.

“This study was a surprise,” he continued. “I think it’s like rheumatoid arthritis was years ago. If you asked docs how they were doing, they would say, ‘My patients are doing great!’ But then you go to the office and measure the patients and it’s like, ‘Well, not so much.’ ”

Another speaker, Eric M. Ruderman, MD , concurred.

“If you say 23% of your rheumatoid arthritis patients are in remission, you’d have to say, ‘I’m not doing a very good job,’ because we’re getting 50%-60% rates of remission these days if you really push medications. And we have good drugs for psoriatic arthritis, too, but I don’t think we’re pushing as hard,” said Dr. Ruderman, professor of medicine and associate chief for clinical affairs in the division of rheumatology at Northwestern University in Chicago.

That being said, it’s also clear that rheumatologists aren’t doing as well in managing psoriatic arthritis as dermatologists are with psoriasis, where skin clearance or almost-clear rates unimaginable just a few years ago are now routinely attainable, he added.

“In dermatology they’re getting better and better and better and better with each successive new cytokine target. We’re not. The ACR responses with risankizumab [an investigational anti-interleukin-23 p19 inhibitor] are very much like we saw with the tumor necrosis factor inhibitors. The interleukin-12/23 inhibitor responses are very much like we’ve seen with the interleukin-17 inhibitors. So each successive improvement in getting skin disease under control hasn’t really gotten us very much further with joint disease. I don’t know that we’ve cracked that yet,” Dr. Ruderman said.

Another recent Scandinavian psoriatic arthritis study that particularly impressed Dr. Kavanaugh was a Danish nationwide cohort registry study that shed new light upon the burdens imposed by the disease in terms of societal costs, comorbid conditions, and disability. The subjects were 10,525 Danes with psoriatic arthritis and nearly 21,000 matched general population controls evaluated during the period from 5 years prior to diagnosis of psoriatic arthritis through 10 years after.

The costs were impressive: an average of 10,641 euros more per year per psoriatic arthritis patient, compared with controls, during the 10-year period following diagnosis, with most of the difference attributed to higher health care costs and forgone earnings due to unemployment, early retirement, or receipt of a disability pension.

At the time of their diagnosis, psoriatic arthritis patients had a significantly higher burden of comorbid conditions than did controls, including a 1.7-fold higher likelihood of cardiovascular disease, a 1.73-fold increase in risk for pulmonary disease, a 2.03-fold greater likelihood of infectious diseases, and a 1.94-fold increased risk of hematologic disorders.

Five years prior to diagnosis of psoriatic arthritis, affected individuals were 1.36-fold more likely than were controls to be on a disability pension. At diagnosis, they were 1.6-fold more likely. Ten years after diagnosis of psoriatic arthritis, they were 2.69-fold more likely to be on a disability pension. Indeed, by that point, 21.8% of Danish psoriatic arthritis patients were on disability ( Ann Rheum Dis. 2017 Sep;76([9]:1495-1501 ).

Health care costs began rising steeply at least 3 years prior to diagnosis of psoriatic arthritis, as well.

“We need to do better with our psoriatic arthritis patients. I think this beautiful study is a call to attention for us to make sure that we’re identifying people with psoriatic arthritis as early as we can,” Dr. Kavanaugh said.

As for the treat-to-target approach that has become so widespread in the management of rheumatoid arthritis, it has gained a toehold in the treatment of psoriatic arthritis. Dr. Kavanaugh was a member of an international task force that recently published treat-to-target recommendations for psoriatic arthritis and axial spondyloarthritis ( Ann Rheum Dis. 2018 Jan;77[1]:3-17 ).

The recommendation for defining the target in psoriatic arthritis was to use the DAPSA or MDA. However, this was a controversial recommendation because of the dearth of evidence. It passed with 51.6% of the task force votes and a level of agreement of 7.9 on a 0-10 scale.

Despite the demonstrable room for improvement in psoriatic arthritis treatment outcomes, better times are likely to be coming for affected patients. A record-breaking number of publications on psoriatic arthritis was published in 2017, and three additional drugs received marketing approval for the disease.

Dr. Kavanaugh and Dr. Ruderman reported serving as consultants to and receiving research grants from numerous pharmaceutical companies.