Abstract
INTRODUCTION: Thrombocytopenia is a common and potentially severe adverse effect of linezolid, but the time to onset during treatment has varied substantially across studies. Moreover, the time to recovery after linezolid withdrawal has not been examined in a larger patient sample. OBJECTIVE: The first objective of this study was to measure the mean time to linezolid-induced thrombocytopenia (LIT) and the second was to measure the mean time to recovery after linezolid discontinuation. METHODS: A retrospective observational cohort study was conducted between January 2017 and December 2022 at Dammam Medical Complex using the medical records of hospitalized adults with normal baseline platelet counts receiving intravenous linezolid for a minimum of 48 hours. All patients included in the analyses received daily platelet count monitoring for up to 14 days after linezolid initiation and 14 days after discontinuation. Thrombocytopenia was defined as a drop in platelet count to <150 × 10(9)/L or <50% of baseline within 14 days. The dose duration-risk relationship and recovery rate were analyzed by constructing Kaplan-Meier survival curves. RESULTS: In total, 334 patients met study inclusion criteria. The mean time to develop thrombocytopenia after starting linezolid was five days, and the mean time of recovery was also 5 days. The cumulative risk of thrombocytopenia reached 100% by day six of therapy, and cumulative recovery reached 100% by day six after linezolid withdrawal, with half of the study population recovering by day four. CONCLUSION: Thrombocytopenia can develop rapidly during linezolid treatment, but recovery after discontinuation is also rapid. Rapid thrombocytopenia is a common adverse effect of linezolid that must be considered prior to prescription, and routine monitoring of platelet count is recommended so that linezolid treatment can be discontinued, if thrombocytopenia occurs.