The development of candidate composite disease activity and responder indices for psoriatic arthritis (GRACE project)

Philip S. Helliwell, Oliver FitzGerald, Jaap Fransen, Dafna D. Gladman, Gerald G. Kreuger, Kristina Callis-Duffin, Neil McHugh, Philip J. Mease, Vibeke Strand, Robin Waxman, Valderilio Feijo Azevedo, Adriana Beltran Ostos, Sueli Carneiro, Alberto Cauli, Luis R. Espinoza, John A. Flynn, Nada Hassan, Paul Healy, Eduardo Mario Kerzberg, Yun Jong LeeEnnio Lubrano, Antonio Marchesoni, Helena Marzo-Ortega, Giovanni Porru, Elvia G. Moreta, Peter Nash, Helena Raffayova, Roberto Ranza, Siba P. Raychaudhuri, Euthalia Roussou, Raphael Scarpa, Yeong Wook Song, Enrique R. Soriano, Paul P. Tak, Ilona Ujfalussy, Kurt De Vlam, Jessica A. Walsh

Research output: Contribution to journalArticlepeer-review


Objective: To develop new composite disease activity indices for psoriatic arthritis (PsA). Methods: Data from routine clinic visits at multiple centres were collected in a systematic manner. Data included all domains identified as important in randomised controlled trials in PsA. Decisions to change treatment were used as surrogates for high disease activity. New indices were developed by multiple linear regression ( psoriatic arthritis disease activity score: PASDAS) and empirically, utilising physician-defined cut-offs for disease activity (arithmetic mean of desirability functions: AMDF). These were compared with existing composite measures: Composite Psoriatic arthritis Disease Activity Index (CPDAI), Disease Activity for PSoriatic Arthritis (DAPSA), and Disease Activity Score for rheumatoid arthritis (DAS28). Results: 161/503 (32%) subjects had treatment changes. Although all measures performed well, compared with existing indices, PASDAS was better able to discriminate between high and low disease activity (area under receiver operating curves (ROC)) curve with 95% CI: PASDAS 0.773 (0.723, 0.822); AMDF 0.730 (0.680, 0.780); CPDAI 0.719 (0.668, 0.770); DAPSA 0.710 (0.654, 0.766); DAS28 0.736 (0.680, 0.792). All measures were able to discriminate between disease activity states in patients with oligoarthritis, although area under the receiver operating curves (AUC) were generally smaller. In patients with severe skin disease ( psoriasis area and severity index >10) both nonparametric and AUC curve statistics were nonsignificant for all measures. Conclusions: Two new composite measures to assess disease activity in PsA have been developed. Further testing in other datasets, including comparison with existing measures, is required to validate these instruments.

Original languageEnglish (US)
Pages (from-to)986-991
Number of pages6
JournalAnnals of the rheumatic diseases
Issue number6
StatePublished - Jun 1 2013
Externally publishedYes

ASJC Scopus subject areas

  • Rheumatology
  • Immunology and Allergy
  • Immunology
  • Biochemistry, Genetics and Molecular Biology(all)


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