title: Platelet count decline: an early prognostic marker in critically ill patients with prolonged ICU stays.
abstract: BACKGROUND
  Thrombocytopenia is common in ICU patients. The objective of this study was to evaluate possible links between declining platelet counts early in the ICU stay and survival.
  
  
  METHODS
  All patients who were admitted to the ICU for at least 5 days and had no thrombocytopenia at the time of admission were included in the study. A multivariable logistic regression model, with hospital mortality as the outcome variable, was built.
  
  
  RESULTS
  We included 1,077 patients in the study. At ICU admission, the median platelet count was not significantly different in survivors (256 x 10(9) cells/L; interquartile range [IQR], 206 to 330 x 10(9) cells/L) and nonsurvivors (262 x 10(9) cells/L; 211 to 351 x 10(9) cells/L). Median simplified acute physiology scores II (SAPS II) at ICU admission was worse in nonsurvivors than in survivors (50 [IQR, 37 to 63] vs 37 [IQR, 27 to 48], respectively; p < 0.0001), as was the mean (+/- SD) sequential organ failure assessment (SOFA) score on day 3 (6.3 +/- 3.24 vs 4 +/- 2.8, respectively; p < 0.0001). Absolute platelet counts were lowest on day 4, but differed significantly between survivors and nonsurvivors only on day 7. Conversely, any percentage decline in platelet counts from 10 to 60% on day 4 was significantly associated with mortality. By multivariable analysis, a 30% decline in platelet count independently predicted death (odds ratio, 1.54; 95% confidence interval, 1.12 to 2.14; p = 0.008), in addition to increasing or stable SOFA scores from ICU admission to day 4, older age, male gender, ICU admission for coma, worse SAPS II score at ICU admission, transfer from another ward, and comorbidity.
  
  
  CONCLUSIONS
  In patients who spend > 5 days in the ICU and have normal platelet counts at ICU admission, a decline in platelet counts provides prognostic information. This parameter deserves to be included in new scoring systems.
authors.affiliation: Medical ICU, Saint Louis Teaching Hospital, 1 Ave Claude Vellefaux, 75010 Paris, France.
authors.forename: Delphine
authors.initials: D
authors.lastname: Moreau
authors.forename: Jean-François
authors.initials: JF
authors.lastname: Timsit
authors.forename: Aurélien
authors.initials: A
authors.lastname: Vesin
authors.forename: Maité
authors.initials: M
authors.lastname: Garrouste-Orgeas
authors.forename: Arnaud
authors.initials: A
authors.lastname: de Lassence
authors.forename: Jean-Ralph
authors.initials: JR
authors.lastname: Zahar
authors.forename: Christophe
authors.initials: C
authors.lastname: Adrie
authors.forename: François
authors.initials: F
authors.lastname: Vincent
authors.forename: Yves
authors.initials: Y
authors.lastname: Cohen
authors.forename: Benoît
authors.initials: B
authors.lastname: Schlemmer
authors.forename: Elie
authors.initials: E
authors.lastname: Azoulay
mesh_terms: D000368:Aged; D015415:Biomarkers / Q000097:blood; D015331:Cohort Studies; D016638:Critical Illness / Q000401:mortality*; D005260:Female; D006801:Humans; D007362:Intensive Care Units; D007902:Length of Stay; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D010976:Platelet Count; D011379:Prognosis; D011446:Prospective Studies; D012720:Severity of Illness Index; D016019:Survival Analysis; D013921:Thrombocytopenia / Q000097:blood* / Q000175:diagnosis / Q000401:mortality*
chemical_list: D015415:Biomarkers