title: Computed tomography-estimated specific gravity at hospital admission predicts 6-month outcome in mild-to-moderate traumatic brain injury patients admitted to the intensive care unit.
abstract: BACKGROUND
  It is clear that patients with a severe traumatic brain injury (TBI) develop secondary, potentially lethal neurological deterioration. However, it is difficult to predict which patients with mild-to-moderate TBI (MM-TBI), even after intensive care unit (ICU) admission, will experience poor outcome at 6 months. Standard computed tomography (CT) imaging scans provide information that can be used to estimate specific gravity (eSG). We have previously demonstrated that higher eSG measurements in the standard CT reading were associated with poor outcomes after severe TBI. The aim of this study was to determine whether eSG of the intracranial content predicts 6-month outcome in MM-TBI.
  
  
  METHODS
  We analyzed admission clinical and CT scan data (including eSG) of 66 patients with MM-TBI subsequently admitted to our neurosurgical ICU. Primary outcome was defined as a Glasgow Outcome Scale score of 1 to 3 after 6 months. Discriminating power (area under the receiver operating characteristic curve [ROC-AUC], 95% confidence interval) of eSG to predict 6-month poor outcome was calculated. The correlation of eSG with the main ICU characteristics was then compared.
  
  
  RESULTS
  Univariate and stepwise multivariate analyses showed an independent association between eSG and 6-month poor outcome (P = 0.001). ROC-AUC of eSG for the prediction of 6-month outcomes was 0.87 (confidence interval: 0.77-0.96). Admission eSG values were correlated with the main ICU characteristics, specifically 14-day mortality (P = 0.004), length of mechanical ventilation (P = 0.01), length of ICU stay (P = 0.045), and ICU procedures such as intracranial pressure monitoring (P < 0.001).
  
  
  CONCLUSIONS
  In this MM-TBI cohort admitted to the ICU, eSG of routine CT scans was correlated with mortality, ICU severity, and predicted 6-month poor outcome. An external validation with studies that include the spectrum of TBI severities is warranted to confirm our results.
authors.affiliation: Department of Anesthesiology and Critical Care, Groupe Hospitalier Pitié-Salpêtrière, Paris, France. degosv@anesthesia.ucsf.edu
authors.forename: Vincent
authors.initials: V
authors.lastname: Degos
authors.forename: Thomas
authors.initials: T
authors.lastname: Lescot
authors.forename: Christian
authors.initials: C
authors.lastname: Icke
authors.forename: Yannick
authors.initials: Y
authors.lastname: Le Manach
authors.forename: Katherin
authors.initials: K
authors.lastname: Fero
authors.forename: Paola
authors.initials: P
authors.lastname: Sanchez
authors.forename: Bassem
authors.initials: B
authors.lastname: Hadiji
authors.forename: Abederrezak
authors.initials: A
authors.lastname: Zouaoui
authors.forename: Anne-Laure
authors.initials: AL
authors.lastname: Boch
authors.forename: Lamine
authors.initials: L
authors.lastname: Abdennour
authors.forename: Christian C
authors.initials: CC
authors.lastname: Apfel
authors.forename: Louis
authors.initials: L
authors.lastname: Puybasset
mesh_terms: D000328:Adult; D000368:Aged; D019540:Area Under Curve; D001929:Brain Edema / Q000000981:diagnostic imaging; D001930:Brain Injuries / Q000000981:diagnostic imaging* / Q000401:mortality / Q000628:therapy; D015331:Cohort Studies; D003422:Critical Care; D003627:Data Interpretation, Statistical; D005260:Female; D015600:Glasgow Coma Scale; D023261:Glasgow Outcome Scale; D006801:Humans; D007362:Intensive Care Units; D007427:Intracranial Pressure / Q000502:physiology; D007902:Length of Stay; D008297:Male; D008875:Middle Aged; D011237:Predictive Value of Tests; D011379:Prognosis; D012372:ROC Curve; D012121:Respiration, Artificial; D013046:Specific Gravity; D014057:Tomography, X-Ray Computed / Q000379:methods*; D016896:Treatment Outcome; D055815:Young Adult