Prospective assessment of the frequency of and risk factors for bleeding events in patients treated with cefazolin

Purpose Major bleedings have been described with cefazolin. The objective was to determine the frequency of bleeding events in cefazolin-treated patients and to identify risk factors for these complications. Methods Monocenter prospective observational study of all consecutive cefazolin-treated patients. Patients benefited from a daily clinical assessment of bleedings and a twice-a-week blood sampling including hemostasis. Bleedings were classified according to the International Society on Thrombosis and Hemostasis classification: major, clinically relevant non-major bleedings (CRNMB) and minor bleedings. Results From September 2019 to July 2020, 120 patients were included, with a mean age of 59.4 (± 20.7) years; 70% of them (84/120) were men. At least 1 CRNMB or major bleeding were observed in 10% of the patients (12/120). Compared to patients with no or minor bleeding, patients with CRNMB or major bleeding were, upon start of cefazolin, more frequently hospitalized in an intensive care unit (7/12, 58.3%, vs. 12/108, 11.1%, P < 0.001, respectively) and receiving vitamin K antagonists (4/12, 33.3%, vs. 8/108, 7.4%, P = 0.019, respectively). After multivariate analysis, patients receiving vitamin K antagonists the day prior bleeding and/or treated for endocarditis were factors associated with an increased risk of CRNMB or major bleeding (odd ratio 1.36, confidence interval 95%, 1.06–1.76, P = 0.020 and 1.30, 1.06–1.61, P = 0.015, respectively). Conclusions Bleeding events associated with cefazolin treatment are frequent. Close clinical monitoring should be performed for patients treated for endocarditis and/or receiving vitamin K antagonists. Hemostasis work-up could be restricted to these patients.