Validação e interpretabilidade clínica do PsAID – Psoriatic Arthritis Impact of Disease

Abstract

Introduction: The psoriatic arthritis is a chronic inflammatory disease, with complex and heterogeneous presentation, that affects one-third of brazilian patients diagnosed with psoriasis. It is associated with functional and psychological impairment which determines a high negative impact on the quality of life of affected patients. In this context, the importance of the inclusion of Patient Reported Outcome Measures (PROM) in the evaluation of psoriatic arthritis has already been recognized, while being possibility to know the real impact of the disease for the patient. However, until very recently, there were no specific PROMs for the psoriatic arthritis disease. Recently, the Psoriatic Arthritis Impact of Disease (PsAID) instrument was developed to evaluate the impact of the disease from a patient's perspective. A twelve-domain version (PsAID-12) was created exclusively for clinical practice. The PsAID has already been validated successfully in European countries, but the psychometric validation of the portuguese version of Brazil has not been performed yet. Furthermore, the relationship of PsAID-12, disease impact measure, with measures of disease activity was still poorly studied. Objective: Validate the brazilian portuguese version of Psoriatic Arthritis Impact of Disease (PsAID-12) and to verify its interpretability clinical, through its relation with measures of psoriatic arthritis activity. Methods: A multicenter cross-sectional study, which recruited 160 patients, who met the Classification criteria for Psoriatic Arthritis (CASPAR), in six Brazilian centers of rheumatology. Reliability was assessed by Cronbach's alpha coefficient and by the Intraclass Correlation Coefficient (ICC). The construct validity was evaluated by exploratory factorial analysis and, also, by Spearman correlation with other PROMs and measures of disease activity evaluation. Results: Of the total number of participants, 50% were female, with a mean age (SD) of 54.0 ± 11.2 years; 68% had only peripheral arthritis and 32% had pure or mixed axial involvement. The majority (67.7%) of the patients were using biological treatment. The reliability of internal consistency (alpha-Cronbach = 0.93) and test-retest (ICC = 0.996) were good. Factor analysis revealed two factors, named physical and psychosocial, which included the skin evaluation item. PsAID-12 correlated significantly with other PROMs, demonstrating good construct validity. PsAID-12 was also significantly associated with the disease activity assessment instruments [Disease Activity Score 28 joints (DAS-28), Bath Ankylosing Spondylitis Disease Activity Index (BASDAI) e Ankylosing Spondylitis Disease Activity Score (ASDAS)] and the MDA index: "Minimum Disease Activity". Fibromyalgia did not significantly affect the final PsAID-12 score. Conclusion: The portuguese version of Brazil of PsAID-12 has been shown to be a reliable and valid measure of the impact of the disease in patients with psoriatic arthritis. Moreover, it associated significantly with the scores of disease activity assessment.