title: Retrospective validation of a β-trace protein interpretation algorithm for the diagnosis of cerebrospinal fluid leakage.
abstract: BACKGROUND
  Cerebrospinal fluid (CSF) leakage is a rare condition that can potentially lead to the development of serious complications. In the last decade, β-trace protein (β-TP) has been shown to be a valuable immunological biomarker that allows prompt and non-invasive identification of CSF leakage. At our institution, the measurement of β-TP has been included in the diagnostic work-up of CSF leakage for more than 10 years. According to our diagnostic algorithm, the presence of CSF in secretion is excluded when β-TP values are <0.7 mg/L, whereas β-TP values ≥1.3 mg/L indicate the presence of CSF in secretion. β-TP values between 0.7 and 1.29 mg/L indicate the presence of CSF if the β-TP ratio (β-TP secretion/β-TP serum) is ≥2. This study aimed to validate this diagnostic algorithm using clinically defined nasal/ear secretions.
  
  
  METHODS
  We performed a retrospective statistical analysis of three β-TP interpretation strategies using data of 236 samples originating from 121 patients with suspect CSF leakage received at our laboratory between 2004 and 2012.
  
  
  RESULTS
  The highest odds ratio was obtained when the proposed algorithm has been used for the interpretation of β-TP results, showing a sensitivity of 98.3% and a specificity of 96%. Positive and negative predictive values were 89.2% and 99.4%, respectively.
  
  
  CONCLUSIONS
  Our data suggest that the proposed β-TP interpretation algorithm is a valuable tool for the diagnosis of CSF leakage in the clinical practice.
authors.forename: Luca
authors.initials: L
authors.lastname: Bernasconi
authors.forename: Theresa
authors.initials: T
authors.lastname: Pötzl
authors.forename: Christian
authors.initials: C
authors.lastname: Steuer
authors.forename: Alexander
authors.initials: A
authors.lastname: Dellweg
authors.forename: Frank
authors.initials: F
authors.lastname: Metternich
authors.forename: Andreas R
authors.initials: AR
authors.lastname: Huber
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000465:Algorithms; D015415:Biomarkers / Q000032:analysis / Q000097:blood; D065634:Cerebrospinal Fluid Leak / Q000175:diagnosis*; D002648:Child; D005260:Female; D006801:Humans; D019746:Intramolecular Oxidoreductases / Q000032:analysis* / Q000097:blood; D054834:Lipocalins / Q000032:analysis* / Q000097:blood; D008297:Male; D008875:Middle Aged; D016017:Odds Ratio; D012189:Retrospective Studies; D012680:Sensitivity and Specificity; D055815:Young Adult
chemical_list: D015415:Biomarkers; D054834:Lipocalins; D019746:Intramolecular Oxidoreductases; C022466:prostaglandin R2 D-isomerase