The frequency of remission and low disease activity in patients with rheumatoid arthritis, and their ability to identify people with low disability and normal quality of life

Abstract

Objective: Treat-to-target in rheumatoid arthritis (RA) recommends targeting remission, with low disease activity (LDA) being an alternative goal. When deciding to target remission or LDA, important considerations are the likelihood of attaining them, and their impacts on function and health-related quality of life (HRQoL). We have addressed this by studying: (a) the frequency of remission and LDA/remission; (b) DAS28-ESR trends after remission; (c) ability of remission vs. LDA to identify patients with normal function (HAQ ≤ 0.5) and HRQoL (EQ-5D ≥ the normal population).

Methods: We studied 571 patients in two clinical trials, and 1693 patients in a 10-year routine care cohort. We assessed the frequency and sustainability of remission and LDA/remission, variability in DAS28-ESR after remission, and sensitivity/specificity of remission and LDA/remission at identifying patients with low disability levels and normal HRQoL using Receiver Operator Characteristic (ROC) curves.

Results: Point remission and remission/LDA were common (achieved by 35-58% and 49-74% of patients, respectively), but were rarely sustained (sustained remission and remission/LDA achieved by 5-9% and 9-16% of patients, respectively). Following attaining remission, DAS28-ESR levels varied substantially. Despite this, of those patients attaining point remission, the majority (53-61%) were in remission at study end-points. Whilst remission was highly specific at identifying patients with low disability (85-91%) it lacked sensitivity (51-57%); similar findings were seen for normal HRQoL (specificity 78-86%; sensitivity 52-59%). The optimal DAS28-cut-off to identify individuals with low disability and normal HRQoL was around the LDA threshold.

Conclusions: Our findings support both the treat-to-target goals. Attaining remission is highly specific for attaining low disability and normal HRQoL, although many patients with more active disease also have good function and HRQoL. Attaining a DAS28-ESR ≤ 3.2 has a better balance of specificity and sensitivity for attaining these outcomes, with the benefit of being more readily achievable. Although sustaining these targets over time is rare, even attaining them on a one-off basis leads to better function and HRQoL outcomes for patients.

Keywords: Function; Health-related quality of life; Rheumatoid arthritis; Treatment targets.