A retrospective study of the risk factors for linezolid-induced thrombocytopenia in hospitalized patients

Introduction: Linezolid is widely used to treat multidrug-resistant Gram-positive infections, often at set doses independent of renal impairment. However, a clear exposure-response association has been established for linezolid-induced thrombocytopenia in patients with renal impairment. The purpose of this study is to assess the prevalence of thrombocytopenia and identify the risk factors for linezolid-induced thrombocytopenia in this population. Methods: A retrospective study was conducted in who had taken standard-dose linezolid for at least 7 days. Patients with apparent thrombocytopenia, abnormal baseline laboratory results, an intensive care unit stay, an estimated glomerular filtration rate (eGFR) variation of >50%, or who received blood or blood products were excluded. Thrombocytopenia was defined as a 25% reduction from the baseline value. To evaluate risk factors, time-to-event analysis with Kaplan-Meier curves and Cox proportional hazards modeling were used. Results: Of the 170 patients enrolled (median age of 69.5 years), 37.1% had an eGFR of <60 mL/min/1.73 m2. Thrombocytopenia developed in 35.3% of patients, occurring at a median of 14 days after linezolid initiation. The proportion of thrombocytopenia was significantly higher in eGFR<60 mL/min/1.73 m2 group compared to eGFR≥60 mL/min/1.73 m2 group (47.6% vs. 28.0%, p<0.001). Cox modeling identified eGFR<60 mL/min/1.73 m2 (adjusted hazard ratio [aHR]=2.287, 95% confidence interval [CI] 1.328–3.907, p=0.0028) and linezolid duration (aHR=0.972, 95% CI 0.946–0.999, p=0.040) as significant risk factors for thrombocytopenia. Conclusions: Thrombocytopenia is more likely in patients with renal impairment who are taking long-term linezolid therapy. Optimizing empirical dosing and adopting therapeutic drug monitoring should be addressed to ensure efficacy and reduce this adverse event in high-risk patients.