Potential difficult-to-treat psoriatic arthritis real-world prevalence and contributing factors.

Objectives: The challenge of achieving low disease activity or remission in psoriatic arthritis (PsA) is an unmet need for many patients. Persistent disease activity in PsA may require treatment adjustments due to its complex pathogenesis and varied tissue involvement, highlighting the need for dedicated definitions. This study evaluates patients' frequency and contributing factors with potential "difficult-to-treat PsA (D2TPsA)", similar to the EULAR definition of D2T rheumatoid arthritis.

Methods: A retrospective study was conducted at two tertiary centres to define potential D2TPsA, defined as failure of ≥1 conventional synthetic disease-modifying anti-rheumatic drug (DMARD) and ≥2 biological or targeted synthetic DMARDs with different mechanisms of action.

Results: Of the 171 patients included in the study, 116 (67.8%) were women; the average age was 48.16 ±11.23 years. D2TPsA was detected in 33 patients (19.3%). This group exhibited a longer disease duration, higher disease burden (median number of tender and swollen joints, patient and physician global evaluation, morning stiffness, erythrocyte sedimentation rate and C-reactive protein, DAPSA), HLA-B27 positivity, and higher prevalence of peripheral involvement. Secukinumab usage and mean glucocorticosteroid dosage were significantly higher in the D2TPsA group. Comorbidities such as fibromyalgia (FM) and diabetes mellitus (DM) and the median number of comorbidities were significantly higher in D2TPsA. In multivariate analysis, FM, DM, and HLA-B27 positivity were independently associated with D2TPsA.

Conclusions: This study underscores the impact of comorbidities on PsA disease activity and emphasises the need for further research to differentiate treatment challenges influenced by comorbidities from true treatment resistance.