Bridging with a single glucocorticoid injection in psoriatic arthritis: Real-world evidence of short-term effectiveness, safety, and enhanced response in high-inflammatory burden patients.

BACKGROUND: The use of adjunctive systemic glucocorticoids (GC) as bridging therapy in psoriatic arthritis (PsA) remains controversial due to limited disease-specific evidence and safety concerns. Although clinical experience suggests potential benefits in selected patients, clear criteria for appropriate use are lacking. The unique pharmacokinetic profile of intramuscular compound betamethasone offers a bridging strategy but has been insufficiently studied. OBJECTIVES: To investigate the real-world effectiveness and safety of single intramuscular GC injection as a bridging therapy for active PsA, and identify clinical characteristics associated with greater therapeutic response. DESIGN: A retrospective observational comparative study using longitudinal clinical data. METHODS: Data were derived from the PKUPsA cohort. Patients receiving a single intramuscular compound betamethasone injection alongside background disease-modifying antirheumatic drugs (DMARDs) were compared with controls not receiving GC. Changes in disease activity, patient-reported outcomes, and adverse events were assessed at 1 month and over 6 months. Negative binomial regression and interaction analysis were used to assess treatment effects and explore differential responses. RESULTS: Of 183 enrolled patients (81 GC, 102 control), the GC group showed higher baseline tender joint count (TJC), Disease Activity in Psoriatic Arthritis (DAPSA), ESR and CRP, but lower Psoriasis Area and Severity Index (PASI). At month 1, the GC group demonstrated greater SJC improvements (ΔSJC: 1 [0 to 2] vs. 0 [0 to 1], P=0.02). Adjusted negative binomial regression confirmed a conditional effect of GC on SJC at month 1, with Johnson-Neyman analysis indicating significance at baseline SJC > 6.6. Treatment benefits were consistent across subgroups and sustained over 6 months. Reported adverse events, including transient PASI increases, were not attributed to GC. CONCLUSION: A single-dose intramuscular injection of compound betamethasone may provide articular improvements with a favorable short-term safety profile. Greater benefits in patients with high-inflammatory burden support its role as a bridging therapy.