title: Accuracy and test characteristics of ancillary tests of cerebrospinal fluid for predicting acute bacterial meningitis in children with low white blood cell counts in cerebrospinal fluid.
abstract: OBJECTIVE
  To determine whether ancillary tests of cerebrospinal fluid (CSF), specifically, the total protein concentration, glucose concentration, and percent neutrophils, provide information for diagnosing acute bacterial meningitis among children with low white blood cell (WBC) count in CSF.
  
  
  METHODS
  The authors retrospectively reviewed CSF from children aged 1 month to 18 years undergoing lumbar puncture at Children's Hospital in Boston from 1993 to 1999. Data were supplemented with CSF test results obtained from children with 0-30 WBCs/mm(3) in CSF diagnosed with acute bacterial meningitis at the same institution from 1984 to 1992. For each test, the incremental value of ancillary tests was estimated by calculating indices of performance such as the area under receiver operator characteristic curves (AUC) and interval likelihood ratios that are relatively insensitive to disease prevalence.
  
  
  RESULTS
  Among children with 0-30 WBCs/mm(3) in CSF who met study criteria, acute bacterial meningitis was identified in ten of 7,701 (0.1%) for the period from 1993 to 1999 and supplemented with 11 additional cases for the period from 1984 to 1992. AUC values for ancillary tests were 0.61 for total protein concentration, 0.69 for glucose concentration, and 0.90 for percent neutrophils. Interval likelihood ratios were unremarkable for mildly abnormal test results. In contrast, interval likelihood ratios for markedly abnormal test results were higher: 22 for total protein concentration >120 mg/dL, 57 for neutrophils >75%, 15 for glucose concentration <20 mg/dL, and 20 for glucose concentration >120 mg/dL.
  
  
  CONCLUSIONS
  When markedly abnormal, results of CSF total protein concentration, glucose concentration, and percent neutrophils have value for diagnosing acute bacterial meningitis, even among children with a low WBC count in CSF.
authors.affiliation: MBChB, Division of Emergency Medicine, Children's Hospital, 700 Children's Drive, Columbus, OH 43205, USA. bonsub@pediatrics.ohio-state.edu
authors.forename: Bema K
authors.initials: BK
authors.lastname: Bonsu
authors.forename: Marvin B
authors.initials: MB
authors.lastname: Harper
mesh_terms: D000293:Adolescent; D002648:Child; D002675:Child, Preschool; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D007958:Leukocyte Count; D016013:Likelihood Functions; D016920:Meningitis, Bacterial / Q000134:cerebrospinal fluid*; D011237:Predictive Value of Tests; D012372:ROC Curve; D012189:Retrospective Studies; D012680:Sensitivity and Specificity