Effect of low-dose aspirin on platelet aggregation inhibition in patients with rheumatoid arthritis

The risk for coronary artery disease (CAD) and mortality has increased in patients with rheumatoid arthritis (RA). Aspirin has anti-thrombotic effects and causes reduction in CAD occurrence in high-risk individuals. The objective of present project was evaluating the influence of low-dose aspirin on inhibition of platelet aggregation in patients with RA.

Forty-eight subjects with RA diagnosed based on the American College of Rheumatology/European League Against Rheumatism (ACR/EULAR) 2010 criteria and age- and sex-matched healthy participants were studied. All subjects received 81 mg/day aspirin for 10 days. Level of the serum thromboxane B2 (sTxB2), a permanent metabolite of thromboxane A2 (TxA2), was measured before and after therapy using enzyme-linked immunosorbent assay (ELISA) kit. The impotency to decrease sTxB2 production to less than 10 ng/ml indicates suboptimal suppression of platelet aggregation via aspirin.

Low-dose aspirin decreased sTxB2 significantly compared with baseline in patients with RA [median interquartile range (IQR): 25.72 (11.78, 90.10) to 7.74 (5.80, 8.82), P < 0.001] and in healthy controls [median (IQR): 40.50 (33.25, 50.90) to 7.30 (4.75, 8.85), P < 0.001]. No remarkable changes were seen in sTxB2 between patients and controls after adjustment (P > 0.050). Pharmacologic influence of aspirin was suboptimal in 6.25% of cases in the presence of higher erythrocyte sedimentation rate (ESR) and in 2.7% of controls. Low-dose aspirin decreased sTxB2 significantly only in patients with Framingham Risk Score (FRS) < 10%.

Low-dose aspirin decreased sTxB2 level and suppressed platelet aggregation and therefore, was effective in primary prevention of cardiovascular (CV) events in patients with RA; however, additional studies are required to reach accurate conclusions.