Time to remission in swollen joints is far faster than patient reported outcomes in rheumatoid arthritis: results from the Ontario Best Practices Research Initiative (OBRI)

Abstract

Objectives: RA patients are often not in remission due to patient global assessment of disease activity (PtGA) included in disease activity indices. The aim was to assess the lag of patient-reported outcomes (PROs) after remission measured by clinical disease activity index (CDAI) or swollen joint count (SJC28).

Methods: RA patients enrolled in the Ontario Best Practices Research Initiative registry not in low disease state at baseline with at ≥6 months of follow-up, were included. Low disease state was defined as CDAI ≤ 10, SJC28 ≤ 2, PtGA ≤ 2cm, pain score ≤ 2cm, or fatigue ≤ 2cm. Remission included CDAI ≤ 2.8, SJC28 ≤ 1, PtGA ≤ 1cm, pain score ≤ 1cm, or fatigue ≤ 1cm. Time to first low disease state/remission based on each definition was calculated overall and stratified by early vs established RA.

Results: A total of 986 patients were included (age 57.4 (12.9), disease duration 8.3 (9.9) years, 80% women). The median (95% CI) time in months to CDAI ≤ 10 was 12.4 (11.4, 13.6), SJC28 ≤ 2 was 9 (8.2, 10), PtGA ≤ 2cm was 18.9 (16.1, 22), pain ≤ 2cm was 24.5 (19.4, 30.5), and fatigue ≤ 2cm was 30.4 (24.8, 31.7). For remission, the median (95% CI) time in months to CDAI ≤ 2.8 was 46.5 (42, 54.1), SJC28 ≤ 1 was 12.5 (11.4, 13.4), PtGA ≤ 1cm was 39.6 (34.6, 44.8), pain ≤ 1cm was 54.7 (43.6, 57.5) and fatigue ≤ 1cm was 42.6 (36.8, 48). Time to achieving low disease state and remission was generally significantly shorter in early RA compared with established RA with the exception of fatigue.

Conclusion: Time to achieving low disease state or remission based on PROs was considerably longer compared with swollen joint count. Treating to a composite target in RA could lead to inappropriate changes in DMARDs.

Keywords: CDAI; LDA; fatigue; outcome measures; patient-reported outcomes; remission; rheumatoid arthritis.