Abstract
OBJECTIVE: Rheumatoid arthritis (RA) and psoriatic arthritis (PsA) are currently treated similarly. However, it is unclear which patient-reported outcome (PRO) domains need specific attention in the management of RA and PsA. Therefore, we aimed to determine the difference in disease impact between matched RA and PsA patients at diagnosis and after 1 year in two different regions. METHODS: RA patients from the treatment in the Rotterdam Early Arthritis CoHort trial (tREACH), PsA patients from the Dutch southwest Early PsA cohoRt (DEPAR) and RA and PsA patients from the Leiden Early Arthritis Clinic (EAC) were included. The difference in disease impact between RA and PsA was measured with the following PROs: pain (Visual Analogue Scale (VAS), 0-100), fatigue (VAS), activity limitation (Health Assessment Questionnaire-Disability Index) and health impact (general health (VAS) and 36-item Short-Form Health Survey (SF-36)). Propensity scores were used to match RA and PsA patients, after which inverse probability weights (IPWs) were calculated. IPW-weighted linear regression models were used to measure PRO differences. RESULTS: 391 RA patients from tREACH, 416 PsA patients from DEPAR, 702 RA and 99 PsA patients from the EAC were included. At diagnosis, PsA-DEPAR patients scored 5.04 units worse (95% CI 2.21 to 7.87) on SF-36 mental health compared with RA-tREACH patients. This difference still existed after 1 year of treatment (3.88 (95% CI 1.90 to 5.86)). PsA-EAC patients had more activity limitations after 1 year of treatment compared with RA-EAC patients (-0.30 (95% CI -0.50 to -0.10)). No significant differences were present in the other PRO domains. CONCLUSION: The disease impact of early RA patients is similar to matched early PsA patients on most PRO domains, except for mental health and functional limitations, which were worse in PsA after 1 year of treatment.