Association between Patient Acceptable Symptom State and disease activity in psoriatic arthritis is disrupted by confounders, including comorbid fibromyalgia

Objective Due to the prevalence of fibromyalgia in psoriatic arthritis (PsA) patients, any evaluation about PsA-specific patient-reported outcomes (PROs) should take in account the possible bias related to this comorbidity. Patient acceptable symptom state (PASS) is a patient-reported measure evaluating the acceptable and/or satisfactory level of symptoms in rheumatic diseases, which has been proposed as a disease activity index, in patients with PsA. Thus, this study was designed to analyse if the association between PASS and PsA disease activity may be biased by the presence of comorbid fibromyalgia. Methods A multi-centre, cross-sectional, observational study enrolling consecutive PsA participants has been conducted from July 2021 to November 2021. The Disease Activity for Psoriatic Arthritis (DAPSA) was collected; the following formulation of PASS question: 'Think about all the ways your PsA has affected you during the last 48 hours. If you were to remain in the next few months as you were during the last 48 hours, would this be acceptable to you?', was submitted to our participants. Results Multivariable logistic regressions, adjusted for the presence of fibromyalgia, did not show any significant association between PASS and DAPSA low disease activity, DAPSA as nominal variable (remission, low disease activity, moderate disease activity, high disease activity) and DAPSA as continuous variable. Conclusion Our data suggest that fibromyalgia influences the patient's perception of the disease and has a negative impact on PASS status independently of disease activity, thus limiting the utility of this Patient reported outcome in real world clinical practice.