title: S100 calcium binding protein B as a biomarker of delirium duration in the intensive care unit - an exploratory analysis.
abstract: BACKGROUND
  Currently, there are no valid and reliable biomarkers to identify delirious patients predisposed to longer delirium duration. We investigated the hypothesis that elevated S100 calcium binding protein B (S100β) levels will be associated with longer delirium duration in critically ill patients.
  
  
  METHODS
  A prospective observational cohort study was performed in the medical, surgical, and progressive intensive care units (ICUs) of a tertiary care, university affiliated, and urban hospital. Sixty-three delirious patients were selected for the analysis, with two samples of S100β collected on days 1 and 8 of enrollment. The main outcome measure was delirium duration. Using the cutoff of <0.1 ng/mL and ≥0.1 ng/mL as normal and abnormal levels of S100β, respectively, on day 1 and day 8, four exposure groups were created: Group A, normal S100β levels on day 1 and day 8; Group B, normal S100β level on day 1 and abnormal S100β level on day 8; Group C, abnormal S100β level on day 1 and normal on day 8; and Group D, abnormal S100β levels on both day 1 and day 8.
  
  
  RESULTS
  Patients with abnormal levels of S100β showed a trend towards higher delirium duration (P=0.076); Group B (standard deviation) (7.0 [3.2] days), Group C (5.5 [6.3] days), and Group D (5.3 [6.0] days), compared to patients in Group A (3.5 [5.4] days).
  
  
  CONCLUSIONS
  This preliminary investigation identified a potentially novel role for S100β as a biomarker for delirium duration in critically ill patients. This finding may have important implications for refining future delirium management strategies in ICU patients.
authors: Indiana University School of Medicine, USA ; Indiana University Center for Aging Research, USA ; Regenstrief Institute, Inc, USA.
authors: Babar A
authors: BA
authors: Khan
authors: Mark O
authors: MO
authors: Farber
authors: Noll
authors: N
authors: Campbell
authors: Anthony
authors: A
authors: Perkins
authors: Nagendra K
authors: NK
authors: Prasad
authors: Siu L
authors: SL
authors: Hui
authors: Douglas K
authors: DK
authors: Miller
authors: Enrique
authors: E
authors: Calvo-Ayala
authors: John D
authors: JD
authors: Buckley
authors: Ruxandra
authors: R
authors: Ionescu
authors: Anantha
authors: A
authors: Shekhar
authors: E Wesley
authors: EW
authors: Ely
authors: Malaz A
authors: MA
authors: Boustani
keywords: S100β; astrocytes; blood–brain barrier; coma