Filling the "GAP" in Real-World Assessment of Psoriatic Arthritis Disease Activity: Performance Characteristics of a Global/Pain Composite Endpoint.

ABSTRACT

INTRODUCTION: Some retrospective data sources, such as electronic health records in the USA, report composite outcome measures not fully validated in psoriatic arthritis (PsA). However, they often contain global assessments, such as a Physician Global Assessment (PhGA) and Patient Global Assessment (PatGA), along with patient-reported pain scores, which individually are considered validated in PsA. This research described the performance characteristics of a 3-item global assessment and pain (GAP) composite endpoint using data from the ixekizumab phase 3 PsA clinical trial program. METHODS: Discrimination of GAP was assessed by comparing placebo to active treatment arms. The magnitude of treatment effect and responsiveness were compared to Disease Activity Index for PsA (DAPSA), clinical DAPSA, DAPSA28, and Psoriatic Arthritis Disease Activity Score (PASDAS) using effect size (ES) and standardized response mean (SRM), respectively. Construct validity was evaluated through correlation among the composite endpoints, and with other physician- and patient-reported outcomes. Change in GAP was compared in patients who reached low disease activity (LDA) levels based on DAPSA, cDAPSA, and PASDAS vs those who did not. RESULTS: GAP discriminated between active treatment and placebo with statistically significant separation as early as week 1. The largest ES/SRM was seen with GAP (2.29/1.74) and PASDAS (2.47/1.68). GAP had the strongest correlation with PASDAS (0.81-0.92) and showed moderate correlations with patient-assessed physical function, low correlations with physician-assessed skin and nail psoriasis, and low to moderate correlation with physician-assessed enthesitis. A significantly greater improvement in GAP was seen in the groups achieving LDA states compared to those not (p < 0.001). CONCLUSION: The GAP composite, an abbreviated endpoint comprising measures common in electronic health records, has promising performance characteristics and could be used to address important clinical questions regarding outcomes and impact of PsA in existing datasets. CLINTRIALS. GOV IDENTIFIER NCT01695239; NCT02349295.

When doctors are assessing patients with psoriatic arthritis in clinical trials, they use tools, which include questions that patients answer and questions that doctors answer, in addition to a physical exam, to help evaluate how patients are doing. In a routine clinical practice setting, all of these same tools may not be used because they take a longer time to document information during a patient office visit. The goals of this research were to (1) create a new tool, which uses questions that patients and doctors answer, to help doctors evaluate how patients with psoriatic arthritis are doing in routine clinical practice, and (2) to assess if this new tool works as well as older tools. The new tool has fewer questions for the doctor and patient to answer and may take less time to document information but may result in some symptoms that patients experience not being regularly assessed. Data from clinical trials were used to compare the new tool to older tools to evaluate if doctors are able to assess psoriatic arthritis the same way. The results of the study showed that doctors are able to assess patients with psoriatic arthritis similarly with the new tool compared to older tools. This information will increase awareness of the new tool and could make it easier for doctors to evaluate patients with psoriatic arthritis in routine clinical practice.