Classification and Outcome Measures for Psoriatic Arthritis

Abstract

Psoriatic arthritis (PsA) is an inflammatory arthritis with multiple manifestations: peripheral/axial arthritis, enthesitis, dactylitis, psoriasis, and nail involvement. From having an agreed upon classification criteria in 2006, the assessment of PsA has advanced from uncertainties to development and validation of numerous specific outcome measures. The Group for Research and Assessment of Psoriasis and Psoriatic arthritis (GRAPPA) has spearheaded the development of a core domain set and is now working on a core outcome measurement set to standardize outcome measures for PsA, that will provide guidance for use of instruments in randomized controlled trials (RCTs) and longitudinal observational studies (LOS). This article summarizes and updates these work processes to improve assessment of this multisystem complex rheumatologic disease.

Keywords: classification criteria; core domains; core instruments; outcome measures; psoriatic arthritis.

Figure 1

Work stream for update of core domain set for PsA 2016. Work processes in circles. *Indicates involvement of patients.

Figure 2

Updated 2016 psoriatic arthritis (PsA) core domain set. Reproduced with permission from Orbai et al. (45). Musculoskeletal (MSK) disease activity includes peripheral joints, enthesitis, dactylitis, and spine symptoms; skin activity includes skin and nails; patient global is defined as patient-reported disease-related health status. The inner circle (core) includes domains that should be measured in all randomized controlled trials and longitudinal observational studies. The middle circle includes domains that are important but may not be feasible to assess in all RCTs and LOS. The outer circle (or research agenda) includes domains that may be important but need further study.