Tabriz University of Medical Sciences Journal of Research in Clinical Medicine 2717-0616 7 4 2019 12 20 Effect of low-dose aspirin on platelet aggregation inhibition in patients with rheumatoid arthritis 110 117 10.15171/jarcm.2019.021 EN Mehrzad Hajialilo https://orcid.org/0000-0001-8152-4583 Amir Ghorbanihaghjo Forough Ghassemi Alireza Khabbazi Aida Malek Mahdavi https://orcid.org/0000-0003-0176-5438 Journal Article 10.15171/jarcm.2019.021 2019 10 16 2019 10 28 Introduction: 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. Methods: 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. Results: 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%. Conclusion: 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.