Predictors of intramuscular glucocorticoid bridge therapy failure in rheumatoid arthritis: a real-world observational study.

BACKGROUND: Intramuscular glucocorticoid (GCs) bridge therapy is an equivalently recommended bridging strategy to oral GCs for rheumatoid arthritis (RA) under predefined tapering and discontinuation schemes. OBJECTIVES: We aimed to investigate the risk factors of intramuscular GCs bridge therapy failure in RA. DESIGN: A retrospective analysis of collected data on RA patients initiating intramuscular betamethasone as bridging therapy. METHODS: In this longitudinal real-world cohort study, 153 RA patients initiating intramuscular betamethasone as bridging therapy combined with csDMARDs (without concurrent biologics/JAK inhibitors) were included. Bridging strategy success under required: (1) GCs discontinuation within 3 months; (2) remission or low disease activity at discontinuation; (3) sustained control without short-term relapse post-discontinuation; (4) no transition to oral GCs and no initiation of b/tsDMARDs during the bridging period. Failure encompassed all other outcomes. Independent predictors were identified via multivariate logistic regression. RESULTS: Among 153 patients receiving intramuscular betamethasone as bridging therapy, 94 (61.4%) experienced bridge therapy failure versus 59 (38.6%) successes. The most common mode for bridging therapy failure was transition to oral GCs (n = 47). The failure group exhibited persistently higher disease activity over 12 months (p < 0.001). Disease activity at intramuscular GCs initiation was significantly elevated in the failure group (median Clinical Disease Activity Index (CDAI): 23.0 (14.8-34.0) vs 13.0 (8.0-22.0), p < 0.001). Multivariate analysis confirmed higher CDAI (OR = 1.05 per unit, 95% CI 1.02-1.10, p = 0.003) and concomitant leflunomide use at GCs initiation (OR = 2.78, 95% CI 1.22-6.25, p = 0.020) as independent failure predictors. CONCLUSION: High disease activity and concurrent leflunomide use at GCs initiation independently predict failure of intramuscular GCs bridge therapy in RA. Early risk stratification may optimize induction therapy selection and potentially improve bridge therapy success rates.