Early reduction in circulating monocyte count predicts maintenance of remission in patients with rheumatoid arthritis treated with anti-TNF therapy

Maintenance of remission once achieved is becoming a critical goal for patients with rheumatoid arthritis (RA) as outcomes improve and advances in therapies continue.1 2 Identification of biomarkers to facilitate tailoring of treatment is often linked to modest response criteria, but less frequently to the more stringent target of sustained remission. We have previously implicated monocytes as potential predictor of response to anti-tumour necrosis factor (TNF) through modulation of regulatory T cells, which may promote maintenance of remission through re-establishment of immune tolerance.3 Circulating monocyte numbers are increased in RA but fall in patients who respond to TNF blockade.4 Whether changes in monocyte numbers can also predict loss of remission, once achieved, to anti-TNF therapy is unknown. We therefore addressed whether the change in monocyte counts in the first year from initiation of anti-TNF therapy (baseline) would predict loss of remission (LOR) in patients who achieved sustained remission. We extracted data (June 2020) from two independent cohorts of adult biologic-naive patients with RA who attained sustained remission while treated with anti-TNF between January 2008 and December 2019 (online supplemental table 1). In this retrospective study, Disease Activity Score-28 (DAS28) with erythrocyte sedimentation rate ≤2.6 on at least two occasions (3–6 months apart) after initiation of anti-TNF therapy was used as the definition of remission, as this index was routinely calculated at the treating hospitals. A more stringent definition of remission based on the Clinical Disease Activity Index (CDAI ≤2.8) …