To investigate the real-world effectiveness and safety of single intramuscular glucocorticoids (GC) injection as a bridging therapy in patients with active psoriatic arthritis (PsA), and identify clinical characteristics associated with greater therapeutic response.

Data were derived from the prospective 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 assessed at 1 month and over 6-month. Negative binomial regression modeled the effect of GC on swollen joint count (SJC) at month 1, and Johnson–Neyman analysis identified baseline SJC thresholds for significant effects.

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), along with numerically greater improvements in ΔTJC (2 [0 to 3] vs. 1 [0 to 2]), ΔDAPSA (4.52 [1.01 to 12.12] vs. 3.08 [0.03 to 8.09]), ΔESR (5 [0 to 15] vs. 2 [-2 to 9]), and ΔCRP (1.5 [-0.2 to 5.8] vs. 0.9 [-0.9 to 4.1]) (Table 1). Adjusted negative binomial regression confirmed a significantly conditional effect of GC on SJC at month 1 (Table 2), with Johnson–Neyman analysis indicating significance at baseline SJC > 6.6 (Figure 1). Subgroup analyses showed consistent benefits, with greater improvements in ΔSJC (median [IQR]: 1 [0-2] vs. 0 [0-1], P=0.03) and ΔVAS (1 [0-2] vs. 0.5 [0-1], P=0.02) in GC＋csDMARDs group compared to that in csDMARDs group. The treatment benefits sustained over 6 months following intramuscular GC bridging therapy at baseline. Reported adverse events, including transient PASI increases and one urinary tract infection, were not attributed to GC.

A single-dose GC injection provides significant and sustained articular improvements with a favorable short-term safety profile. Greater benefits in patients with high-inflammatory burden support its role as a bridging therapy.