Background/Purpose: PsA is associated with multiple disease domains, requiring the use of different clinical measures and patient-reported outcomes (PROs) to assess improvements in disease activity following treatment. However, the relationship between clinical measures and PROs is not well understood. The objective of this post hoc analysis was to evaluate associations between Minimal Disease Activity (MDA) and a set of PROs.

Methods: All available data from two Phase 3 studies in patients with PsA (OPAL Broaden [12 months; NCT01877668]; OPAL Beyond [6 months; NCT01882439])^1,2 were analyzed. MDA in PsA, as a binary outcome, is defined as meeting ≥ 5/7 of the following criteria: tender joint count ≤ 1; swollen joint count ≤ 1; Psoriasis Activity and Severity Index ≤ 1 or body surface area ≤ 3%; patient global disease activity Visual Analog Scale (VAS) ≤ 20; Patient’s Assessment of Arthritis Pain VAS (Pain) ≤ 15; HAQ-Disability Index (DI) score ≤ 0.5; and tender entheseal points ≤ 1. For the purpose of this analysis, an alternative MDA outcome is proposed (ScoreMDA) by considering every criterion as an individual item (ie 1 if true and 0 if false, to give a score range of 0–7; scores ≥ 5 indicate the patient had MDA). A set of PROs was analyzed (Table 1). A repeated measures regression model was used to evaluate the relationship between ScoreMDA and PROs. A sensitivity analysis to assess the linearity assumption was performed using ScoreMDA as a categorical anchor (represented by integer values 0–7).

Results: Results indicated a linear relationship between ScoreMDA and PROs, which was similar across all PROs and in both Phase 3 studies. For example, in OPAL Broaden, a 1-point difference in ScoreMDA was associated with a mean (95% CI) difference in SF‑36 Physical Component Summary (PCS) score of 2.0 points (1.9, 2.2) (OPAL Beyond: 2.5 points [2.3, 2.7]) (Figure 1). These results indicate that improvements in any one MDA criterion is associated with an improvement in SF‑36 PCS score approaching clinical relevance (clinically important difference [CID] for SF‑36 PCS is 3 points) and improvements in any two criteria in MDA is associated with an improvement in SF‑36 PCS score that exceeds the CID. Results were closely aligned when ScoreMDA was used as a categorical or a continuous anchor, thus supporting a linear relationship between ScoreMDA and the PROs.

Conclusion: There was a robust linear relationship between ScoreMDA and selected PROs. Results were similar across studies, suggesting that they may be generalizable to different populations. This method provides insight into the relationships between clinical measures and PROs in PsA, which could aid their interpretation and facilitate the assessment of disease activity.

1. Gladman D et al. N Engl J Med 2017;377:1525–36.
2. Mease P et al. N Engl J Med 2017;377:1537–50.

Acknowledgments: Study sponsored by Pfizer Inc. Medical writing support was provided by Jennifer Higginson of CMC Connect and funded by Pfizer Inc.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/relationships-between-minimal-disease-activity-and-patient-reported-outcomes-in-patients-with-psoriatic-arthritis-post-hoc-analysis-of-two-phase-3-studies/