Baseline ESR-CRP difference (D score) and JAK inhibitor discontinuation for loss of efficacy after biologic failure in rheumatoid arthritis

ObjectivesTo assess whether baseline ESR-CRP difference (D score) is associated with discontinuation due to loss of efficacy during Janus kinase inhibitor therapy after biologic failure in rheumatoid arthritis. MethodsSingle-centre retrospective cohort of 24 patients with rheumatoid arthritis who initiated a Janus kinase inhibitor after inadequate response to at least one biologic DMARD. D score was ESR (mm/h) minus CRP (mg/L). The primary outcome was discontinuation due to loss of efficacy; other discontinuations were censored. Kaplan-Meier curves and Cox models were used. ResultsSeven patients discontinued due to loss of efficacy. After dichotomisation at the median D score (20.3; n = 12 per group), 1-year LOE-free persistence was 90.9% in the high D group and 43.2% in the low D group (log-rank p = 0.004). The hazard ratio per 10-unit increase was 0.47 (95% CI 0.29 to 0.76; p = 0.002) and 0.41 after age adjustment (0.22 to 0.74; p = 0.003). ConclusionsBaseline D score was associated with lower risk of discontinuation due to loss of efficacy. Larger studies are needed. Key messagesO_LILoss-of-efficacy discontinuation tended to cluster in patients with low ESR and low CRP at baseline. C_LIO_LIHigher baseline D score was associated with fewer loss-of-efficacy discontinuations during JAK inhibitor therapy. C_LIO_LID score from ESR and CRP may complement post-biologic treatment decisions, pending external validation. C_LI