Using Patient-Reported Outcomes to Distinguish Between Low Disease Activity and Remission in Psoriatic Arthritis

By M. Elaine Husni, MD, MPH, and Juliette Yedimenko, MD

Rheumatologists rely on several composite instruments to measure disease activity in patients with psoriatic arthritis. These tools typically examine the number of swollen and tender joints, as well as the number of tendons and percentage of skin involved. However, very few composite instruments include patient-reported outcomes, which may have the potential to determine low disease expression or remission.

We collaborated with colleagues from New York University, the University of Pennsylvania and the University of Utah to study the ability of patient-reported outcomes to independently differentiate between states of low disease activity and remission in psoriatic arthritis based on validated composite indices.

Capturing a more complete picture

All major treatment guidelines advocate the treat-to-target approach for psoriatic arthritis, which affects the joints, skin, eyes and gastrointestinal system. The goal is to decrease inflammation, reduce radiographic progression and improve function and quality of life. However, it’s difficult to capture all the components of this complex inflammatory disease using one of the existing composite tools.

Patient-reported outcomes could indicate the residual impact of psoriatic arthritis on function and quality of life that isn’t readily obtained by standard composite instruments, laboratory data and clinical examinations.

Our retrospective cross-sectional study examined data from 2016 to 2019 in a national database of adult psoriatic patients from the four participating institutions, which comprise the Psoriatic Arthritis Research Consortium (PARC). We used three patient-reported outcome tools:

• Patient-Reported Outcomes Measurement Information System (PROMIS) measures of Physical Health, Mental Health and Fatigue.

• Routine Assessment of Patient Index Data 3 (RAPID3).

• EULAR Psoriatic Arthritis Impact of Disease (PSAID12).

The study included 227 patients. The team looked for correlations between patients who identify as having low disease activity or remission based on patient-reported outcomes and more objective data, such as physician assessments and lab results.

Study results point to value of patient-reported outcomes

Our initial hypothesis was that subjective, patient-reported outcomes could be influenced by other disease states and therefore might not be able to distinguish between low disease activity and remission. However, the results suggest otherwise.

One of our primary findings is that patients who were in remission as indicated by one of three traditional composite measures — minimal disease activity (MDA), clinical disease activity index (CDAI) or disease activity in psoriatic arthritis (DAPSA) scores — all had significantly better PROMIS scores in the physical, mental and fatigue domains, as well as PSAID12 scores. In addition, when considering RAPID3 questionnaires, low disease severity and near remission were reported by nearly all the patients who were in remission according to traditional composite tools.

Potential impact on clinical practice and treatments

Accurate assessment of disease activity in psoriatic arthritis is key in clinical practice so physicians can help guide informed treatment decisions, and adding in the patient’s perception of their disease provides another dimension in the assessment. Our study emphasizes the importance of patient-reported outcomes to ascertain remission and low disease activity.

The study is one of several research projects PARC members hope to conduct with the goal of tailoring treatment and perhaps tapering psoriatic arthritis patients with low disease activity and remission off medication.