['To determine whether levels of plasma-soluble triggering receptor expressed on myeloid cells-1 (sTREM-1) are elevated in patients with rheumatoid arthritis (RA) and whether levels are correlated with disease activity and other variables.', 'Our study included 71 patients with RA and 50 age- and sex-matched healthy controls. Clinical characteristics and laboratory measures, including erythrocyte sedimentation rate (ESR), C-reactive protein (CRP), and 28-joint Disease Activity Score (DAS28) were assessed. Plasma levels of sTREM-1 and tumor necrosis factor-α (TNF-α) were measured by ELISA.', 'Patients with RA had significantly higher plasma sTREM-1 levels than healthy controls (170.10 ± 84.71 pg/ml vs 97.41 ± 40.64 pg/ml; p < 0.001). In patients with RA, plasma sTREM-1 levels were found to be correlated with DAS28, ESR, CRP, white blood cell counts, neutrophil counts, and plasma TNF-α levels (r = 0.329, p = 0.005; r = 0.241, p = 0.043; r = 0.314, p < 0.001; r = 0.261, p = 0.028; r = 0.278, p = 0.019; and r = 0.313, p = 0.009, respectively). Plasma sTREM-1 levels in patients with active disease status (DAS28 > 3.2) were significantly higher than in those with low disease status (DAS28 ≤ 3.2; 208.89 ± 100.14 pg/ml vs 150.29 ± 68.70 pg/ml; p = 0.005).'] Are levels of plasma-soluble triggering receptor expressed on myeloid cells-1 ( sTREM-1 ) correlated with disease activity in rheumatoid arthritis?