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Updated: Nov 15, 2025

Author Spotlight: Self-Assessment Protocol for Predicting Psoriatic Arthritis in Psoriasis Patients
Published on: March 1, 2024
Composite Measures for Routine Clinical Practice in Psoriatic Arthritis: Testing of Shortened Versions in a UK
William Tillett1, Oliver FitzGerald1, Laura C Coates1
1As part of the supplement series GRAPPA 2020, this report was reviewed internally and approved by the Guest Editors for integrity, accuracy, and consistency with scientific and ethical standards. This report is independent research funded by the National Institute for Health Research (NIHR), Programme Grants for Applied Research (Early detection to improve outcome in patients with undiagnosed PsA [PROMPT], RP-PG-1212-20007). The views expressed are those of the authors and not necessarily those of the NIHR or the Department of Health and Social Care. W. Tillett, BSc, MBChB, PhD, FRCP, N.J. McHugh, MBChB, MD, FRCP, FRCPath, Department of Pharmacy and Pharmacology, University of Bath, and Royal National Hospital for Rheumatic Diseases, Bath, UK; O. FitzGerald, MD, FRCPI, FRCP(UK), Conway Institute for Biomolecular Research, University College Dublin, Dublin, Ireland; L.C. Coates, MB ChB, PhD, Nuffield Department of Orthopaedics, Rheumatology and Musculoskeletal Sciences, University of Oxford, Oxford, UK; J. Packham, DM, FRCP, Haywood Rheumatology Centre, Stoke-on-Trent, UK; D.R. Jadon, MBBCh, MRCP, PhD, University of Cambridge, Cambridge, UK; M. Massarotti, MD, Department of Rheumatology, University Hospitals Dorset NHS Foundation Trust, Christchurch, New Zealand; M. Brook, Patient Resesarch Partner, E. Korendowych, PhD, MRCP, Royal National Hospital for Rheumatic Diseases, Bath, UK; S. Lane, MBChB, MD, FRCP, Ipswich Hospital NHS Trust, Ipswich, UK; P. Creamer, MBChB, North Bristol NHS Foundation Trust, Bristol, UK; A. Antony, MBBS, School of Clinical Sciences, Monash University, Melbourne, Australia; A. Rambojun, PhD, Department of Pharmacy and Pharmacology, University of Bath, Bath, UK; P.S. Helliwell, MD, PhD, Professor of Clinical Rheumatology, Leeds Institute of Rheumatic and Musculoskeletal Medicine, University of Leeds, and National Institute for Health Research Leeds Biomedical Research Centre, Leeds, UK. SL has received sponsorship for both the European Alliance of Associations for Rheumatology and the American College of Rheumatology this year, both from AbbieVie, and last year for Madrid from Celgene, but no commercial work for any organizations. All other authors declare no conflicts of interest. Address correspondence to Dr. W. Tillett, Department of Rheumatology, Royal National Hospital for Rheumatic Diseases, Coombe Park, Bath, BA1 3NG, UK.
Objective:
To test shortened versions of the psoriatic arthritis (PsA) composite measures for use in routine clinical practice.
Methods:
Clinical and patient-reported outcome measures (PROMs) were assessed in patients with PsA at 3 consecutive follow-up visits in a UK multicenter observational study. Shortened versions of the Composite Psoriatic Arthritis Disease Activity Index (CPDAI) and Group for Research and Assessment of Psoriasis and Psoriatic Arthritis (GRAPPA) Composite Exercise (GRACE) measures were developed using PROMs and tested against the Disease Activity Score in 28 joints (DAS28), composite Disease Activity in Psoriatic Arthritis, and Routine Assessment of Patient Index Data (RAPID3). Discrimination between disease states and responsiveness were tested with the t-score, standardized response mean (SRM), and effect size (ES). Data were presented to members at the GRAPPA 2020 annual meeting and members voted on the recommended composite routine practice.
Results:
The SRM for the GRACE, 3 visual analog scale (VAS), and 4VAS were 0.67, 0.77, and 0.63, respectively, and for CPDAI and shortened CPDAI (sCPDAI) were 0.54 and 0.55, respectively. Shortened versions of the GRACE increased the t-score from 7.8 to 8.7 (3VAS) and 9.0 (4VAS), but reduced the t-score in the CPDAI/sCPDAI from 6.8 and 6.1. The 3VAS and 4VAS had superior performance characteristics to the sCPDAI, DAS28, Disease Activity in Psoriatic Arthritis, and RAPID3 in all tests. Of the members, 60% agreed that the VAS scales contained enough information to assess disease and response to treatment, 53% recommended the 4VAS for use in routine care, and 26% the 3VAS, while leaving 21% undecided.
Conclusion:
Shortening the GRACE to VAS scores alone enhances the ability to detect status and responsiveness and has the best performance characteristics of the tested composite measures. GRAPPA members recommend further testing of the 3VAS and 4VAS in observational and trial datasets.

