Background/Purpose:

Physical function is one of the major outcomes in RA as it predicts work disability, quality of life, 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.

To investigate the course of functional status assessed by health assessment questionnaire (HAQ) in RA patients with sustained clinical remission 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=4863) by the respective sponsors. We identified patients, who at some point during the trials achieved sustained remission in consecutive visits of at least 6 months by the DAS28-CRP < 2.6 or SDAI ≤ 3.3. We obtained HAQ scores during these 6 month remission periods, and were thus able to investigate the course of physical function over time in sustained remission using the Wilcoxon test. Furthermore we explored the proportion of patients achieving full function (HAQ = 0 over time period investigated).

Results:

Out of 4362 patients we identified 605 patients in sustained remission by DAS28-CRP, and 385 patients by SDAI. No significant differences of baseline characteristics were found between these two groups. We found a significant decrease of mean HAQ values over time within the first 6 months in remission 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) as well as 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 remission by SDAI compared to DAS28-CRP at remission entry until month 4 in sustained remission. Achievement of full function (HAQ=0 over course of remission) was observed in 42.5% of patients in DAS28-CRP and 50.1 % of patients in SDAI remission at beginning  of sustained remission, 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 remission entry only 57.4% of patients in DAS28-CRP REM fulfilled SDAI remission; 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 remission went at least partly in parallel with the increasing frequency of SDAI remission in DAS28 remitters over time.

Conclusion:

Physical function continuous to improve over time in sustained remission. The stringency of the remission criteria determines how quickly patients in remission achieve their best possible functional improvement.

Fig. 1 Course of HAQ in DAS-CRP and SDAI sustained remission over time