title: Retrospective analysis of the risk factors for linezolid-induced thrombocytopenia in adult Japanese patients.
abstract: BACKGROUND
  Thrombocytopenia is a major side effect of linezolid therapy. However, there are few reports about the risk factors for linezolid-induced thrombocytopenia.
  
  
  OBJECTIVE
  The aim of this study is to evaluate the risk factors for thrombocytopenia in patients who undergo linezolid therapy.
  
  
  METHODS
  Aomori Prefectural Central Hospital in Japan, a tertiary 695 beds hospital.
  
  
  METHODS
  A retrospective review was performed using the hospital's medical records. From January 2010 to August 2012, 75 adult patients who received linezolid therapy were enrolled in this study.
  
  
  METHODS
  Linezolid-induced thrombocytopenia was defined as a decrease in the patient's platelet count to <10 × 10⁴/μL or a reduction of ≥30 % from their baseline value. Odds ratios (OR) for thrombocytopenia were analyzed using multivariate stepwise logistic regression analysis.
  
  
  RESULTS
  Thrombocytopenia occurred in 29 patients (38.6 %), seven of whom required platelet transfusions. The patients who developed thrombocytopenia were significantly older, displayed a significantly higher frequency of renal insufficiency, and received linezolid therapy for significantly longer than the patients without thrombocytopenia. Stepwise logistic regression analysis suggested that receiving linezolid therapy for ≥14 days was a significant risk factor for thrombocytopenia [OR 13.3, 95 % confidence interval (CI) 3.2-55.6, p < 0.01], whereas the creatinine clearance rate exhibited a significant negative correlation with the incidence of the condition [OR 0.98, 95 % CI 0.96-0.99, p = 0.037]. The incidence of thrombocytopenia among the patients who demonstrated creatinine clearance rates of <30 mL/min was 60 % (12/20), which was significantly higher than that observed among the patients who displayed creatinine clearance rates of more than 60 mL/min (26.4 %, 9/34, p = 0.014).
  
  
  CONCLUSIONS
  Receiving linezolid therapy for ≥14 days and a low creatinine clearance rate were suggested to be risk factors for linezolid-induced thrombocytopenia. The platelet counts of patients with these risk factors should be closely monitored.
authors.affiliation: Department of Pharmacy, Aomori Prefectural Central Hospital, Aomori, Japan, r.hirano1115@gmail.com.
authors.forename: Ryuichi
authors.initials: R
authors.lastname: Hirano
authors.forename: Yuichi
authors.initials: Y
authors.lastname: Sakamoto
authors.forename: Naoki
authors.initials: N
authors.lastname: Tachibana
authors.forename: Motoki
authors.initials: M
authors.lastname: Ohnishi
mesh_terms: D000081:Acetamides / Q000008:administration & dosage / Q000009:adverse effects* / Q000627:therapeutic use; D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D000890:Anti-Infective Agents / Q000008:administration & dosage / Q000009:adverse effects* / Q000627:therapeutic use; D005260:Female; D006767:Hospitals, District; D006801:Humans; D015994:Incidence; D007239:Infections / Q000150:complications / Q000188:drug therapy*; D007564:Japan / Q000453:epidemiology; D000069349:Linezolid; D008297:Male; D008875:Middle Aged; D023303:Oxazolidinones / Q000008:administration & dosage / Q000009:adverse effects* / Q000627:therapeutic use; D010976:Platelet Count; D017713:Platelet Transfusion; D051437:Renal Insufficiency / Q000150:complications*; D012189:Retrospective Studies; D012307:Risk Factors; D062606:Tertiary Care Centers; D013921:Thrombocytopenia / Q000097:blood / Q000139:chemically induced* / Q000453:epidemiology / Q000628:therapy
chemical_list: D000081:Acetamides; D000890:Anti-Infective Agents; D023303:Oxazolidinones; D000069349:Linezolid