Background/Aims Although continuous composite measures of disease activity for PsA assessment exist, more feasible abbreviated measures are needed for routine screening. The 3VAS and 4VAS scores, developed by abridging the Group for Research and Assessment of Psoriasis and Psoriatic Arthritis (GRAPPA) Composite Exercise (GRACE) measure, are the first short multidimensional composite measures specifically for routine PsA care. 3VAS/4VAS showed superior performance vs. several established composite measures using small datasets. However, GRAPPA members recommended further testing of 3VAS/4VAS in observational and trial datasets.

Methods This post hoc analysis used pooled data through W24 from all treatment groups in the DISCOVER 1/2 and COSMOS studies. Correlation of 3VAS/4VAS with DAPSA, PASDAS, PhGA and PtGA was assessed with Pearson’s correlation coefficient, minimal important difference (MID) with four distribution-based methods and minimal detectable change (MDC) with the standard formula (Table 1). Clinically relevant thresholds for low, moderate and high disease activity were estimated with receiver operating characteristic analysis and DAPSA (≤4, >4-≤14, >14-≤28, >28), PASDAS (≤1.9, >1.9-≤3.2, >3.2-<5.4, ≥5.4) and PhGA/PtGA (≤1, >1-≤3, >3-≤6, >6 cm) as anchors.

Results This analysis included 1405 patients: 51.3% were male, with a mean (sd) age of 47.1 (11.8) and PsA duration of 6.4 (6.5) years. The mean baseline 3VAS, 4VAS, DAPSA, PASDAS, PhGA and PtGA scores reflected high disease activity levels (Table 1). Through W24, 3VAS and 4VAS showed very strong correlation with PtGA (r3VAS=0.92, r4VAS=0.94) and PASDAS (r3VAS=0.81, r4VAS=0.82), strong with PhGA (r3VAS=0.77, r4VAS=0.74) and moderate-to-strong with DAPSA (r3VAS=0.59, r4VAS=0.61). Calculated MIDs were 0.9 for 3VAS and 0.9 for 4VAS; MDCs were 3.3 for 3VAS and 3.2 for 4VAS (Table 1). Cut-off values for low, moderate and high disease activity were 2.0, 3.4 and 4.9 for 3VAS, and 2.1, 3.5 and 5.1 for 4VAS.

Conclusion Using a large pooled clinical trial dataset of patients with active PsA, we have calculated clinically relevant thresholds for improvement, as well as disease activity thresholds, for 3VAS and 4VAS. These estimates are generally comparable to those previously reported and may facilitate setting treatment targets and screening disease activity in routine care when resources are limited or in remote patient monitoring.