Clinical disease activity is a major determinant of plasma D-dimer elevation in outpatients with rheumatoid arthritis: A hospital-based cross-sectional study.

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

METHODS: 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 enrollment. Patients with elevated D-dimer levels underwent whole-leg venous ultrasonography to diagnose deep vein thrombosis (DVT).

RESULTS: 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 = 0.003), high and moderate clinical disease activity index (CDAI) (OR 8.79, p < 0.001), and the presence of comorbidities or cardiovascular/VTE risk factors (OR 2.94, p = 0.017) were identified as the factors independently associated with high D-dimer levels. Among patients with D-dimer ≥3 μg/ml, ten (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 μg/ml vs. 4.1 μg/ml, p < 0.001).

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