Abstract
INTRODUCTION: We sought to identify and compare treatment response groups based on individual patient responses (rather than group mean response) over time on the Clinical Disease Activity Index (CDAI) for rheumatoid arthritis (RA), in patients treated with baricitinib 4-mg in 4 phase 3 studies. METHODS: Trajectory subgroups were identified within each study using growth mixture modeling. Following grouping, baseline characteristics and disease measures were summarized and compared. RESULTS: In each study, three response trajectories were identified. In the three studies of patients naïve to biological disease-modifying anti-rheumatic drugs (bDMARDs) patients had, on average, high disease activity, as measured by CDAI. In these studies, a group of rapid responders (65-71% of patients) had the lowest baseline CDAI scores and achieved mean CDAI ≤ 10 by week 16. Gradual responders (10-17%) had higher baseline CDAI, but generally achieved low disease activity (CDAI ≤ 10) by week 24. A group of partial responders (18-22%) had higher baseline CDAI and did not achieve mean CDAI ≤ 10. In bDMARD-experienced patients, the subgroups were rapid responders, who achieved mean CDAI ≤ 10 (42% of patients); partial responders, with mean CDAI decrease of ~ 15 points from baseline (42% of patients); and limited responders (15% of patients). Changes in modified total sharp score (mTSS; assessed only in biologic-naïve patients) were below the smallest detectable difference at 24/52 weeks for > 90% of patients in each group, excepting partial responders in RA-BEGIN (≥ 75% no detectable change). CONCLUSION: In patients receiving baricitinib 4-mg, lower baseline CDAI was generally associated with rapid response, while higher baseline CDAI scores were generally seen for patients who either reached treatment targets more gradually, or who had a partial or limited response. Maintenance of response was observed with continued baricitinib treatment in all response groups and generally included maintenance of mTSS.