Although the goal of a 28-joint Disease Activity Score (DAS28-ESR) <2.6 is highly specific for attaining low disability and normal health-related quality of life in rheumatoid arthritis (RA), a good specificity for attaining the same outcomes can be seen with a goal of a DAS28-ESR ≤3.2, which may be a more readily achieved goal, according to a study published in Seminars in Arthritis and Rheumatism.

A treat-to-target approach for RA recommends setting remission as a treatment goal, with low disease activity as an alternative goal. The current study was used to address the considerations that clinicians and patients need to take into account when deciding which goal to target: frequency of remission (DAS28-ESR <2.6) and low disease activity/remission (DAS28-ESR ≤3.2), DAS28-ESR trends after remission, and the ability of low disease activity vs remission to identify patients with normal function and health-related quality of life.

A total of 571 patients from 2 clinical trials and 1693 patients from a 10-year routine care cohort were included. Assessments included the sustainability and frequency of remission and low disease activity/remission as well as DAS28-ESR variability after remission and used Receiver Operator Characteristic (ROC) curves to measure the specificity and sensitivity of remission and low disease activity/remission to identify patients with low disability and normal health-related quality of life.

Sustained remission was rare in all 3 cohorts (5% to 9% of patients), with sustained low disease activity/remission being more common (9% to 16% of patients). Point remission was readily achievable (35% to 58% of patients), and point low disease activity/remission was more common (49% to 74% of patients). Sustained remission was highly specific for normal EQ-5D (93% to 97%) and low disability (97% to 98%) but lacked sensitivity (normal EQ-5D 19% to 36%; low disability 19% to 29%), with many participants who did not  attain sustained remission still having good health-related quality of life and function. After remission attainment, substantial variation was seen in DAS28-ESR levels; however, the majority of patients attaining point remission were in remission at their study end points (53% to 61%). The optimal cut-off for DAS28-ESR to identify patients with low disability levels and normal health-related quality of life was observed around the low disease activity threshold.

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Study investigators concluded that the findings support both targets recommended in the treat-to-target strategy. Furthermore, they conclude that the “goal of a DAS28-ESR of <2.6 is highly specific for the attainment of low disability and normal [health-related quality of life], although many patients with more active disease also have good function and [health-related quality of life]. The goal of a DAS28-ESR of <3.2 also has a good specificity for attaining these outcomes, and has the benefit of being more readily achievable. Although sustaining these targets over time is relatively rare, even attaining them on a one-off basis leads to better function and [health-related quality of life] outcomes for patients with RA.”

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Reference

Scott IC, Ibrahim F, Panayi G, et al. 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 [published online December 28, 2018]. Semin Arthritis Rheum. doi:10.1016/j.semarthrit.2018.12.006