What Influences Patients' Opinion of Remission and Low Disease Activity in Psoriatic Arthritis? Principal Component Analysis of an International Study

Objectives In psoriatic arthritis (PsA), the treatment objective is remission (REM) or low disease activity (LDA), but patients' perception of REM is poorly studied. This analysis aimed to identify factors associated with patient-defined REM. Methods This analysis uses ReFlaP data, an international PsA study, with REM defined as "At this time, is your psoriatic arthritis in remission, if this means: you feel your disease is as good as gone?". Variables associated with first patient-defined REM and secondly LDA were identified using multivariable logistic regression and principal component analysis (PCA) to explore correlated variables. Results Of 424 patients (50.2% male, mean age 52 years) with established disease, 94 (22.2%) reported themselves as being in REM and 191 (45.0%) as LDA alone. In multivariable analysis pain, psoriasis, impact of disease, physician opinion of symptoms from joint damage, and Groll comorbidity index were independent predictors of remission. For LDA, results were similar. Using PCA, variance explained was 74% by 5 components for men and 80% by 6 components for women. The key component from PCA for remission was, for both genders, disease impact (PsAID, pain, HAQ) explaining 22.2-27.5% of variance. Other factors included musculoskeletal disease activity, chronicity/joint damage, psoriasis, enthesitis and CRP. For LDA, similar factors were identified but the variance explained was lower (64-68%). Conclusion Many factors impact on patients' opinion of remission, dominated by disease impact. Disease activity in multiple domains, chronicity/age, comorbidities and symptoms due to other conditions contribute to a robust model highlighting that patient defined "remission" is multifaceted.