Conference Coverage

PASDAS beats DAS28 in measuring psoriatic arthritis treat-to-target success



Measuring success with a treat-to-target strategy in psoriatic arthritis patients proved to be more comprehensive with the Psoriatic Arthritis Disease Activity Score (PASDAS) than it was with the Disease Activity Score in 28 joints (DAS28), according to findings from a prospective cohort study.

Fewer patients had a low disease activity score according to DAS28, and a higher percentage of patients deemed adequately treated according to DAS28 were found to have residual disease activity, compared with the number of patients so categorized according to PASDAS, researcher Michelle Mulder reported in her presentation of the study at the virtual annual meeting of the Group for Research and Assessment of Psoriasis and Psoriatic Arthritis (GRAPPA).

“PASDAS implementation in a tightly monitored PsA [psoriatic arthritis] cohort suggests relevant residual disease burden, even though DAS28 was measured at every visit previously,” said Ms. Mulder, an MD/PhD student at Sint Maartenskliniek in Nijmegen, The Netherlands.

The presentation was convincing to Philip Helliwell, MD, PhD, who is a professor of clinical rheumatology at Leeds (England) University, and was also one of the developers of PASDAS. “We know it can be used in clinical practice with a certain amount of organization and clinical staff to help you,” he said during another presentation at GRAPPA.

Treat to target is a widely accepted therapeutic strategy. It’s particularly common in rheumatoid arthritis, but increasing evidence suggests that it improves patient outcomes in psoriatic arthritis. DAS28 is frequently used in treat-to-target approaches in rheumatoid arthritis, and often gets applied to psoriatic arthritis since rheumatologists are already comfortable with it, according to Ms. Mulder. “However, DAS28 has shown some limitations when used in psoriatic arthritis. For example, its joint count is limited to only 28 joints, and it does not take all PsA domains into account,” she said.

DAS28 was previously used at Sint Maartenskliniek in combination with psoriatic arthritis–specific assessment recommendations, but the institution opted in 2019 to switch to PASDAS, which was developed by GRAPPA and the European League Against Rheumatism. “To better adhere to international PsA guidelines, we chose to implement PASDAS in our cohort with the assumption that it might improve patient care,” Ms. Mulder said.

With DAS28, clinicians measured the C-reactive protein (CRP) and Patient Global Visual Analog Scale (VAS) domains and were advised to examine 28 joints for tender and swollen joint count domains. Under the PASDAS guidance, clinicians examined 68 joints for tenderness, 66 joints for swelling, CRP, Patient Global VAS, Physician Global VAS, Leeds Enthesitis Index, dactylitis, and the 12-item Short Form Physical Composite Scale. They also examined the skin, nails, and axial disease.

To examine the effects of the switch from DAS28 to PASDAS, the researchers compared outcomes in 855 patients before and after the change during March to December 2019. The mean age of patients was 55 years, and 46% were female. The mean disease duration was 10 years, and the mean PASDAS score was 3.1. A total of 96% of participants were negative for anti-cyclic citrullinated peptide. Overall, 30% had arthritis, 9% had axial disease, 3% had dactylitis, 21% had enthesitis, 51% had skin disease, and 42% had nail disease.

About three-quarters (77.4%) of patients reached the threshold of low disease activity (LDA) according to the DAS28 measure, while 53.1% did so using the PASDAS. High disease activity occurred in 7.8% of patients according to DAS28, compared with 2.7% as measured by PASDAS. Patients who reached only the DAS28 LDA target but not the PASDAS target, compared with patients who reached the LDA target in both measures, had significantly worse counts for swelling in 66 joints (0.7 vs. 0.2; P < .001) and tenderness in 68 joints (2.1 vs. 0.7; P < .001), as well as worse scores for enthesitis (0.5 vs. 0.1; P < .001), dactylitis (4% vs. 1%; P = .005), patient global VAS (44.0 vs. 14.4; P < .001), Health Assessment Questionnaire (0.8 vs. 0.4; P < .001) and Patient Acceptable Symptom State (unacceptable score in 17% vs. 3%; P < .001).

Ms. Mulder acknowledged that PASDAS imposes a significant burden on clinicians, and noted that Sint Maartenskliniek created patient infrastructure to handle the load. “It’s very important that you set up your clinic in a specific way. When the patient comes in, we draw blood immediately and we ask them to fill in the questionnaires, and then they go to a specialized nurse who measures all the different components of the PASDAS. It took a lot of time to train the specialized nurses and to implement the PASDAS score in our electronic health records. After we did those things, it was quite easy because we have this whole setup. It takes time and it is difficult, but it is definitely possible to do it,” Ms. Mulder said during a live Q&A following her prerecorded presentation.

The study received no funding. Ms. Mulder had no relevant financial disclosures. Dr. Helliwell has financial ties to AbbVie, Amgen, Celgen, Galapagos, Janssen, Novartis, Pfizer, and UCB.

SOURCE: Mulder M et al. GRAPPA 2020 Virtual Annual Meeting.

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