title: An increase in mean platelet volume after admission is associated with higher mortality in critically ill patients.
abstract: BACKGROUND
  Platelet activation and consumption are common in critically ill patients and are associated with poorer prognosis. Mean platelet volume is a simple surrogate for platelet activation, with higher MPV being associated with worse clinical condition on a large array of clinical diagnoses. We therefore aimed to investigate associations between changes in platelet count and mean platelet volume (MPV) with prognosis and inflammatory cytokine values in critically ill patients.
  
  
  METHODS
  This study prospectively included 84 critically ill patients. Patients were stratified into four groups according to proportional changes in MPV (ΔMPV24h) and platelet count (ΔPlat24h) in the first 24 hours after admission. Mortality between groups was compared using the χ (2) test. Logistic regression was performed using hospital mortality as outcome and Simplified Acute Physiology Score (SAPS 3), ΔPlat24h and ΔMPV24h as covariates. Concentrations of the following inflammatory mediators were measured using Miliplex® technology: IL1β, IL6, IL8, IL10, epidermal growth factor, vascular endothelial growth factor, TNFα and IFNα. Cytokine concentrations were compared between groups using the Kruskal-Wallis test with Bonferroni correction.
  
  
  RESULTS
  Patients in whom MPV increased and platelet count decreased had higher mortality rates (46%). According to logistic regression, ΔMPV24h was independently associated with increased mortality (OR 1.28 per 1% increase; 95% CI 1.08 to 1.48). No strong associations between inflammatory mediators and changes in MPV and platelet count were found.
  
  
  CONCLUSIONS
  An increase in MPV after admission to an ICU is independently associated with higher hospital mortality.
authors.affiliation: Intensive Care Unit, Emergency Medicine Discipline, Hospital das Clínicas, University of São Paulo, São Paulo, Brazil ; Laboratory of Medical Investigation 51 (LIM 51), Faculty of Medicine, University of São Paulo, São Paulo, Brazil ; Intensive Care Unit, Hospital Alemão Oswaldo Cruz, São Paulo, Brazil.
authors.forename: Fernando G
authors.initials: FG
authors.lastname: Zampieri
authors.affiliation: Intensive Care Unit, Emergency Medicine Discipline, Hospital das Clínicas, University of São Paulo, São Paulo, Brazil.
authors.forename: Otavio T
authors.initials: OT
authors.lastname: Ranzani
authors.affiliation: Intensive Care Unit, Emergency Medicine Discipline, Hospital das Clínicas, University of São Paulo, São Paulo, Brazil.
authors.forename: Viviane
authors.initials: V
authors.lastname: Sabatoski
authors.affiliation: Laboratory of Medical Investigation 51 (LIM 51), Faculty of Medicine, University of São Paulo, São Paulo, Brazil.
authors.forename: Heraldo Possolo
authors.initials: HP
authors.lastname: de Souza
authors.affiliation: Laboratory of Medical Investigation 51 (LIM 51), Faculty of Medicine, University of São Paulo, São Paulo, Brazil.
authors.forename: Hermes
authors.initials: H
authors.lastname: Barbeiro
authors.affiliation: Intensive Care Unit, Emergency Medicine Discipline, Hospital das Clínicas, University of São Paulo, São Paulo, Brazil.
authors.forename: Luiz Monteiro Cruz
authors.initials: LM
authors.lastname: da Neto
authors.affiliation: Intensive Care Unit, Emergency Medicine Discipline, Hospital das Clínicas, University of São Paulo, São Paulo, Brazil.
authors.forename: Marcelo
authors.initials: M
authors.lastname: Park
authors.affiliation: Laboratory of Medical Investigation 51 (LIM 51), Faculty of Medicine, University of São Paulo, São Paulo, Brazil.
authors.forename: Fabiano
authors.initials: F
authors.lastname: Pinheiro da Silva
keywords: Critical illness; Endothelial activation; Inflammation; Platelet