Guselkumab effectiveness in real world settings: observations from an Italian multi-center study

Objectives Guselkumab is a biologic disease-modifying antirheumatic drug (bDMARD) with proven efficacy for psoriatic arthritis (PsA) in randomized controlled trials. Evidence of its effectiveness from clinical practice remains limited. We evaluated the real-world effectiveness of guselkumab for PsA (primary objective) and identified factors influencing clinical outcomes. Methods This retrospective, observational, multicentre study enrolled consecutive patients with PsA prescribed guselkumab for joint involvement at 26 Italian rheumatology referral centres. Baseline data included patient history, PsA subtype, treatment history, disease activity. Treatment effectiveness was assessed with Kaplan-Meier curves; Cox proportional hazards analysis identified factors associated with treatment persistence. Results The study included 278 patients (median age: 57 years [Interquartile Range, IQR: 50–63]; 64.4% female); median observation 10.7 months (IQR: 5.3–15.9; total: 3,332.6 patient-months). Retention rates at 6, 12, and 24 months were 90.4%, 80.0%, and 67.8%, respectively. Reasons for discontinuation included primary inefficacy (48% of 54 cases), secondary inefficacy (41%), and skin/mucosal intolerance (4%). Statistically significant factors (p < 0.05) influencing treatment persistence included sex, smoking, concurrent conventional synthetic DMARDs (csDMARDs), corticosteroid use, year of prescription, and axial or enthesitic involvement. Conclusions Approximately two-thirds of PsA patients treated with guselkumab remained on therapy after two years. Adverse events motivated < 10% of discontinuations. Effectiveness was higher in patients with enthesitic or axial PsA and in those without concurrent corticosteroids or csDMARDs, confirming the effectiveness and safety of guselkumab as an optimal choice for monotherapy, particularly in PsA patients with enthesitis, with or without joint impairment, and/or axial involvement.