3-Item Global Assessment and Pain Composite Enhances PsA Outcome Analysis

William Tillett, BSc

Credit: University of Bath

A 3-item Global Assessment and Pain composite demonstrated promising performance characteristics and can help address important clinical questions regarding psoriatic arthritis (PsA) outcomes, a recent study showed.

“Following recent reports of the potential benefits of abbreviated PsA composite measures for use in routine clinical practice, we introduced an alternative 3-item composite (GAP) and described its performance characteristics,” wrote investigators, led by William Tillett, BSc, from department of rheumatology at Royal National Hospital for Rheumatic Disease, in Bath, UK. “The analyses demonstrate that the [Global Assessment and Pain] composite has good discrimination and a high degree of responsiveness in PsA, comparable to PASDAS, and higher than all the DAPSA composites assessed.”

Electronic health records in the US do not always have fully validated composite outcome measures for PsA. Although many records have validated data such as Physician Global Assessment, Patient Global Assessment, and patient-reported pain scores, this is only sometimes the case.

Recently, research has shown shortened composites could be more practical to use in a real-world setting.2 Investigators sought to describe the performance characteristics of a 3-item Visual Analog Scale comprised of a Physician Global Assessment, Patient Global Assessment, and Patient Skin VAS with Global Assessment and Pain as the primary endpoint.

The team leveraged data from 2 randomized, double-blind, phase 3 clinical trials of ixekizumab in patients with active PsA (SPIRIT-P1 and SPIRIT-P2). SPIRIT-PT evaluated 80 mg ixekizumab every 2 weeks (n = 103) or 4 weeks (n = 107) after starting a 160 mg starting a 160 mg dose or adalimumab (n = 106). At week 24, participants on placebo or adalimumab were re-randomized to receive ixekizumab 160 mg every 2 or 4 weeks.

Tillett and colleagues examined the composite endpoints of Global Assessment and Pain, Disease Activity Index for PsA (DAPSA), cDAPSA, DAPSA28, PASDAS, and MDA. Investigators determined the Global Assessment and Pain composite by comparing participants on placebo to active treatment. They also compared the extent of treatment effect and responsiveness to the Disease Activity Index for PsA (DAPSA), clinical DAPSA, DAPSA28, and Psoriatic Arthritis Disease Activity Score using effect size and standardized response mean, respectively.

Global Assessment and Pain share performance similarities with PASDAS since both consider the multidimensional nature of PsA and include the patient-and-physician-global score. In contrast, DAPSA is more unidimensional and focused on articular disease.

Investigators evaluated construct validity through correlation among the composite endpoints and with other physician-and-patient-reported outcomes. They also compared changes in global assessment and pain composite in patients who reached low disease activity levels based on DAPSA, cDAPSA, and PASDAS and patients who did not.

The Global Assessment and Pain measure showed a clear, statistically significant difference between the active treatment and the placebo groups as early as the first week of treatment. Global Assessment and Pain (2.29/ 1.74) and PASDAS (2.47/ 1.68) had the most noticeable effect size and standardized response mean.

Ultimately, Global Assessment and Pain had the strongest correlation with PASDAS (0.81 – 0.92) and a moderate correlation with patient-assessed physical function, low correlations with physician-assessed skin and nail psoriasis, and low to moderate correlation with physician-assessed enthesitis. Groups achieving low disease activity had significantly greater improvement (76% - 79%) in Global Assessment and Pain than those who did not (P < .001).

“The [Global Assessment and Pain] composite provides an opportunity for an alternative abbreviated composite endpoint that includes components commonly found in electronic health records, has comparable performance characteristics to the PASDAS, and is feasible to use in a real-world setting,” investigators concluded. “The [Global Assessment and Pain] composite could be used to address important clinical questions regarding outcomes and impact of PsA in existing datasets.”

^References

1. ^{Tillett W, Birt J, Vadhariya A, Ross S, Ngantcha M, Ng KJ. Filling the "GAP" in Real-World Assessment of Psoriatic Arthritis Disease Activity: Performance Characteristics of a Global/Pain Composite Endpoint. Rheumatol Ther. Published online July 2, 2024. doi:10.1007/s40744-024-00690-1}
2. ^{Helliwell PS, FitzGerald O, Fransen J, et al. The development of candidate composite disease activity and responder indices for psoriatic arthritis (GRACE project). Ann Rheum Dis. 2013;72:986–91. https://doi.org/10.1136/annrheumdis-2012-201341.}