Clinical disease activity is a major determinant of plasma D-dimer elevation in outpatients with rheumatoid...

To identify factors associated with plasma D-dimer levels in outpatients with rheumatoid arthritis (RA).

We consecutively recruited 460 RA patients who visited our hospital for routine follow-ups between June and October 2021. Plasma D-dimer, RA-related characteristics, comorbidities, and cardiovascular and venous thromboembolism (VTE) risk factors were examined at enrolment. Patients with elevated D-dimer levels underwent whole-leg venous ultrasonography to diagnose deep vein thrombosis (DVT).

Participants had no DVT signs or symptoms. Among them, 252 (54.8%) were positive for plasma D-dimer (≥0.5 μg/ml) and 40 (8.7%) had high D-dimer levels (≥3 μg/ml). The mean was 1.07 μg/ml. After adjustments, age [odds ratio (OR) 1.88 per additional 10 years, P = .003], high and moderate clinical disease activity index (OR 8.79, P < .001), and the presence of comorbidities or cardiovascular/VTE risk factors (OR 2.94, P = .017) were identified as the factors independently associated with high D-dimer levels. Among patients with D-dimer levels ≥3 μg/ml, 10 (25%) had DVT in their lower limbs, and D-dimer levels were significantly higher in patients with DVT compared with those without it (mean 6.0  vs. 4.1 μg/ml, P < .001).

Clinical disease activity is a major contributor to plasma D-dimer elevation in RA outpatients.