medwireNews: Patients with rheumatoid arthritis (RA) have a significantly elevated risk for venous thromboembolism (VTE), suggest study findings published in Arthritis Care and Research.
RA patients were 2.4 times more likely to develop VTE than age-, gender-, and index date-matched patients without RA, with an incidence rate of 6.1 and 2.5 episodes per 1000 person-years, respectively.
And the risk remained 1.4 times higher after adjusting for 20 different confounding factors, such as comorbidity, pregnancy, hormone use, and recent surgery, report Seoyoung Kim and co-workers from Brigham and Women's Hospital in Boston, Massachusetts, USA.
The adjusted risks for deep vein thrombosis and pulmonary embolism in RA patients versus other patients were 1.2 and 1.9, respectively.
The study included medical claims data for 22,143 patients with two diagnoses of RA and at least one filed prescription for a disease-modifying anti-rheumatic drug, and 88,572 patients without RA.
In a subgroup analysis of 4153 patients with baseline levels of acute phase reactants available - such as erythrocyte sedimentation rate or C-reaction protein level - the risk for VTE was 1.5-fold higher in RA patients than controls. This did not reach statistical significance, owing to the small number of events in this subgroup, the researchers say.
Of note, around a third of RA patients and controls who developed VTE had a major risk factor for thrombosis in the 90 days beforehand, such as recent surgery, hospitalization, or diagnosis of cancer.
Kim et al comment that although "the link between RA and VTE is not yet clearly understood, it has been thought that hypercoagulability is induced by active systemic inflammation and production of cytokines such as TNF-alpha and IL-1."
"These inflammatory cytokines can lead to endothelial dysfunction, down-regulation of protein C and inhibition of fibrinolysis."
They suggest that future research should examine the impact of disease-modifying antirheumatic drugs and tumor necrosis factor inhibits on the risk for VTE in this population.
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