Factors Associated with Health-Related Quality of Life in Psoriatic Arthritis Patients: A Longitudinal Analysis

Introduction Psoriatic arthritis (PsA) is considered a multifaceted disease, with patients reporting low health-related quality of life (HRQoL). Data on disease burden are substantial and there exists a need for properly designed studies to learn more about the evolution of HRQoL in this condition. This study aims to identify factors associated to HRQoL evolution in PsA patients followed-up in a real-world setting in Spain. Methods We conducted a retrospective longitudinal observational study including incident patients from the rheumatology outpatient clinic of Hospital Clinico San Carlos (Madrid, Spain), diagnosed for the first time of PsA, defined as having received any ICD9/ICD10 diagnosis code of PsA, from 2007 to 2016, and followed-up until loss of follow-up, death, or November 2017. The influence of demographic and clinical variables in baseline HRQoL [assessed with the Rosser Classification Index (RCI)] was analyzed using bivariable and multivariable generalized linear models. The influence of those variables and of treatment-related factors in repeated measures of HRQoL was analyzed using bivariable and multivariable generalized estimating equations (GEE) models nested by patient. Results Two hundred and thirty patients were included in the analysis, with 3384 registered visits. At baseline, older age, a previous diagnosis of obesity, and the presence of enthesitis were significantly associated with worse HRQoL. During follow-up, using an exchangeable working correlation structure, the presence of enthesitis was also associated with worse HRQoL, coefficient (95% CI) - 0.006 (- 0.01 to - 0.002), p = 1.00E-03; conversely, treatment with methotrexate or antimalarials was associated with better HRQoL with 0.007 (0.001-0.014), p = 0.020 and 0.003 (0.001-0.005), p = 3.00E-03, respectively. Conclusions Musculoskeletal manifestations and comorbidities exert a deleterious effect in HRQoL of PsA patients. Therefore, the optimal management of this condition needs to also address these manifestations in order to try to restore the QoL of these patients.