Establishment and validation of a risk prediction model incorporating concentrations of linezolid and its metabolite PNU142300 for linezolid-induced thrombocytopenia.

Background: Linezolid-induced thrombocytopenia is the main factor restricting the clinical application of linezolid.
Objectives: To investigate the relationship between PNU-14230 concentration and linezolid-induced thrombocytopenia and further develop and validate a risk model for predicting linezolid-induced thrombocytopenia.
Methods: A regression model was constructed to predict the occurrence of linezolid-induced thrombocytopenia, and further externally validated. The predictive performance was evaluated by receiver operating characteristic curve and Hosmer-Lemeshow test. Linezolid Cmin and PNU-142300 concentrations were compared for different kidney function groups. The Kaplan-Meier method was used to estimate the difference in cumulative incidence of linezolid-induced thrombocytopenia among different kidney function patients.
Results: In the derivation (n = 221) and validation (n = 158) cohorts, 28.5% and 24.1% of critically ill patients developed linezolid-induced thrombocytopenia. Logistic regression analysis indicated that the independent risk factors were linezolid Cmin, PNU-142300 concentration, baseline platelet count, renal insufficiency (RI) and continuous venovenous haemofiltration (CVVH). The AUC for the risk model was 0.901, and the model was good (P = 0.633). The model also showed good discrimination (AUC 0.870) and calibration (P = 0.282) in the external validation cohort. Compared with normal kidney function patients, patients with RI and CVVH had higher linezolid Cmin and PNU-142300 concentrations (P < 0.001) and higher cumulative incidence of linezolid-induced thrombocytopenia (P < 0.001).
Conclusions: PNU142300 concentration, as well as linezolid Cmin, might identify patients at risk of linezolid-induced thrombocytopenia. The risk prediction model had good predictive performance for linezolid-induced thrombocytopenia development. Concentrations of linezolid and PNU-142300 accumulated in patients with RI and CVVH.
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