Background To date is known that an early and aggressive control of disease activity results in significantly better clinical, functional and radiographic outcomes in patients with psoriatic arthritis (PsA). A variety of clinical instruments are currently available for measuring the disease activity in PsA. However they have been validated, mainly in clinical trials, in which stringent inclusion criteria are taken into account and not always reflect the “real world” setting.
Objectives to compare “in a real-world” setting the performance of the most common composite activity indices in a cohort of PsA patients.
Methods A total of 171 PsA patients were involved. The following variables were evaluated: peripheral joint assessment, patient-reported of pain, physician and patient assessments of disease activity, patient general health status, dactylitis digit count, Leeds Enthesitis Index (LEI), Health Assessment Questionnaire (HAQ), physical component summary score (PCS) of the Medical Outcome Survey Short form-36 (SF-36), Psoriasis Area and Severity Index (PASI), Dermatology Life Quality Index (DLQI), C-reactive protein (CRP) and erythrocyte sedimentation rate (ESR). The 28-disease activity score (DAS28)-ESR/CRP, Simple Disease Activity Index (SDAI), Composite Psoriatic Disease Activity Index (CPDAI), as Disease Activity for PSoriatic Arthritis (DAPSA) and Psoriatic Arthritis Disease Activity Score (PASDAS) have also been calculated. The criteria for Minimal Disease Activity (MDA) and remission were applied as external criterion.
Results Receiver Operating Characteristic (ROC) curves were similar all the composite measures. Only the CPDAI showed less discriminative ability. There was a high degree of correlation between all the indices (p<0.0001). The highest correlations were between DAPSA and SDAI (rho =0.996) and between DAPSA and DAS28-CRP (rho =0.957). CPDAI, DAPSA and PASDAS had the most stringent definitions of remission and minimal disease activity (MDA) category. DAS28-ESR and DAS28-CRP had the highest proportions in terms of remission and MDA.
Conclusions Although a good concurrent validity and discriminant capacity of six disease activity indices were observed, the proportions of patients classified in the disease activity levels differed. In particular, the rate of patients in remission was clearly different among the respective indices.
Disclosure of Interest None declared