Thrombocytopenia Associated with Linezolid Therapy in Solid Organ Transplant Recipients: A Retrospective Cohort Study

Background: Linezolid is associated infrequently with bone marrow suppression in immunocompetent patients, but hematologic complications from linezolid in transplant recipients are understudied. This study evaluated the hematologic safety of linezolid in solid organ transplant recipients. Methods: We performed a retrospective study of inpatients at our institution treated with linezolid from June 1, 2009 until June 6, 2012. The solid organ transplant cohort (TP) was compared with the non-transplant cohort (NTP) using parameters related to linezolid safety. Outcomes included incidences of leukopenia or thrombocytopenia at the end of linezolid treatment (EOT), lengths of stay, and blood product requirements. Results: The TP cohort included 110 patients; the NTP cohort included 583 patients. Baseline parameters were similar between the TP and NTP cohorts. Non-transplant patients were more likely to have methicillin-resistant Staphylococcus aureus (MRSA), whereas TP patients received more doses of linezolid (17.0 vs. 11.3, p<0.001) and were more likely to receive other drugs associated with thrombocytopenia (91.7% vs. 11.3%, p<0.0001). Transplant patients with normal platelet counts at baseline were more likely to have EOT thrombocytopenia (29.3% vs. 10.7%, p=0.005), and multivariable regression analysis confirmed only a beginning platelet count less than 150,000 platelets per micoliter to be significantly different between groups: 43% TP versus 26.9% NTP (p=0.0009) making it the only independent predictor of EOT thrombocytopenia. Finally, TP patients were more likely to require platelet transfusions compared with the NTP cohort. Conclusions: Transplant patients who received linezolid had a higher incidence of EOT thrombocytopenia and platelet transfusions, compared with NTP. Transplant patients who are thrombocytopenic at baseline are at the greatest risk. These findings may relate to more frequent use of drugs associated with marrow suppression or greater linezolid exposure in the TP cohort. Clinicians caring for transplant patients should take into account this higher risk of thrombocytopenia and need for platelets when considering use of linezolid in this population.