Background Remission has been proposed as the therapeutic target in RA. Physical function, on the other hand, is one of the major outcomes in RA predicting work disability, health care resource utilisation and mortality. It is currently still unclear what the minimum duration of remission is that would improve functional capacity to the best possible degree.
Objectives To investigate the course of functional status assessed by health assessment questionnaire (HAQ) in RA patients with sustained clinical remission (REM) for at least 6 months.
Methods We were provided a random 80-90% data sample of RA patients enrolled in recent clinical trials (ASPIRE, ATTRACT, DE019, ERA, Leflunomide, PREMIER, and TEMPO; n=4362) by the respective sponsors. We identified patients, who at some point during the trials achieved REM by the Disease Activity Score using 28 joint counts and C-reactive protein (DAS28-CRP ≤2.6) or Simplified Disease Activity Index (SDAI ≤3.3), and who maintained it in all subsequent visits throughout at least 6 months.We obtained HAQ scores during these 6 month REM periods, and were thus able to investigate the course of physical function over time in sustained REM using the Wilcoxon test. In additional analyses, patients with a HAQ=0 at REM entry were excluded as they had a priori no chance to show improvement during sustained REM.
Results Out of 4362 patients we identified 605 patients in sustained remission by DAS28-CRP (mean duration of REM 38.8±25.1 weeks), and 385 patients by SDAI (mean duration 37.2±23.7 weeks). There were no significant differences in baseline characteristics between these two groups. A significant decrease of HAQ over time was found over the first 6 months in REM by DAS28-CRP (mean±SD HAQ monthly from baseline to month 6: 0.25±0.4 to 0.22±0.38 to 0.22±0.39 to 0.21±0.38 to 0.20±0.37 to 0.18±0.31 to 0.16±0.32) or SDAI (0.17±0.3 to 0.16±0.32 to 0.15±0.3 to 0.14±0.29 to 0.13±0.29 to 0.13±0.26 to 0.11±0.27) with significantly (p<0.05) lower levels of HAQ in SDAI REM compared to DAS28-CRP at REM entry until month 4 in sustained REM). At entry into REM, full function (HAQ=0 over course of REM) was observed in 42.5% of patients in DAS28-CRP and 50.1% of patients in SDAI REM, and in more patients with early RA (DAS28-CRP: 47.6%; SDAI: 52.6%) compared to late RA patients (DAS28-CRP: 33.3%; SDAI: 44.1%). Further, at REM entry only 57.4% of patients in DAS28-CRP REM fulfilled SDAI REM; this percentage increased over time to 71.9% at 3 months and 76.9% at 6 months of sustained remission; thus, the improvement of HAQ in DAS28 REM went at least partly in parallel with the increasing frequency of SDAI REM in DAS28 remitters over time.When excluding patients with HAQ=0 at REM entry, again, absolute HAQ values were lower in patients with SDAI REM (n=192) than in DAS28-CRP REM (n=349). Patients in SDAI-REM showed steeper relative improvement over the first visits compared to DAS28-CRP REM with a total improvement of 30% compared to 35.8% in DAS28-CRP REM.
Conclusions Functional capacity is significantly improving when remission is reached, but continues to improve if remission is sustained. The stringency of the remission criteria determines how quickly patients in remission achieve their best possible functional improvement.
Disclosure of Interest H. Radner: None Declared, F. Alasti: None Declared, J. Smolen Consultant for: Abbott, Amgen, Centocor, Pfizer and Sanofi, D. Aletaha Consultant for: Abbott, Amgen, Centocor, Pfizer and Sanofi