Bykerk VP, Lee EB, van Vollenhoven R, et al. - To better understand tofacitinib treatment responses, group-based trajectory modeling was applied to evaluate distinct disease activity trajectories and associated baseline variables in patients with active rheumatoid arthritis (RA). Researchers used post hoc analysis data from a phase III study of methotrexate-naïve patients receiving tofacitinib 5 mg twice daily. They used changes in Disease Activity Score in 28 joints, erythrocyte sedimentation rate (DAS28-4[ESR]) from baseline to month 24 in group-based trajectory modeling to distinguish distinct disease activity trajectories. They compared patient and disease characteristics, changes in radiographic progression and patient reported outcomes, and safety up to month 24 among trajectory groups. A total of 346 methotrexate-naïve patients were included in the study. The results showed that distinct phenotypic subgroups distinguished heterogeneity in patients with RA normally examined as a single population. The outcomes suggested that trajectory modeling may enable separation of clinically meaningful subsets of patients with RA, and may help optimize treatment outcomes.