OBJECTIVES: The aim of the present study was to investigate the association of high-sensitivity C-reactive protein (hs-CRP) with bleeding events among patients with acute coronary syndrome (ACS) received dual antiplatelet therapy (DAPT) after percutaneous coronary intervention. DESIGN: An observational and multicentre study was conducted among non-ST-segment elevation ACS (NSTE-ACS). SETTING: The study was conducted at five medical centres in China. PARTICIPANTS: This study retrospectively included 2583 adults with NSTE-ACS between 1 January 2010 and 31 December 2014. PRIMARY AND SECONDARY OUTCOME MEASURES: The primary outcome was major bleeding, defined by the Bleeding Academic Research Consortium definition (grades 3-5). The second outcome was death and any bleeding. RESULTS: 53 (2.1%) patients experienced major bleeding in the hospital. Patients with hs-CRP levels greater than 8.20 mg/L had the highest incidence of in-hospital major bleeding (25 (3.9%), p<
0.001) compared with the other groups. Multivariable analysis indicated that hs-CRP was an independent factor associated with in-hospital major bleeding (continuous: adjusted OR=1.01, 95% CI: 1.01 to 1.02, p<
0.001
quartiles: adjusted OR for quartile 4 (referring to quartile 1) =3.71, 95% CI: 1.35~10.23, p=0.011), which was further confirmed by subgroup analysis and receiver operating characteristic curves. The restricted cubic spline analysis demonstrated an S-shaped association between hs-CRP and major bleeding. During the 5-year follow-up, there was a significantly high risk of bleeding in patients with higher hs-CRP levels. CONCLUSIONS: Systemic inflammation marker hs-CRP in patients with NSTE-ACS who received DAPT is associated with a high risk of in-hospital major bleeding. An S-shaped association was found between hs-CRP and bleeding events. Further studies are warranted to optimise antithrombotic drug therapy in high bleeding risk patients during follow-up.