title: Lumbar puncture ordering and results in the pediatric population: a promising data source for surveillance systems.
abstract: BACKGROUND
  The Centers for Disease Control and Prevention is incorporating laboratory data into real-time surveillance systems. When normal patterns of laboratory test orders and results are modeled, aberrations can be detected. Because many test orders are available electronically well before results, atypical patterns of test ordering may signal outbreaks.
  
  
  OBJECTIVE
  The authors sought to characterize baseline patterns in the ordering and early results of lumbar punctures, motivated by the possibility of using these data for real-time surveillance for early detection of meningitis or encephalitis outbreaks.
  
  
  METHODS
  Retrospective cohorts of pediatric emergency department patients at a single hospital (1993-2003) and from the National Hospital and Ambulatory Medical Care Survey (1992-2000) were used for analysis.
  
  
  RESULTS
  Test ordering exhibits seasonal patterns, with monthly peaks in January and August (p < 0.0001). For the hospital cohort, the rate of cerebrospinal fluid pleocytosis exhibits seasonal patterns (p < 0.0001), with a peak from August to October. This is strongly associated with the rate and pattern of clinical neurologic disease (p < 0.0001). A long-term secular decline in daily test ordering is evident, dropping from 5.3 to 2.9 in the hospital sample, and from 371.8 to 185.3 in the national sample (p < 0.001). The long-term rate of pleocytosis has declined (p < 0.0001), though the yield of testing for pleocytosis has improved (p = 0.0104).
  
  
  CONCLUSIONS
  Laboratory test patterns correspond with those of clinical disease and are a promising source of surveillance data. Using such data for real-time monitoring requires specific adjustments for patient age, periodicities, and secular trends.
authors.affiliation: Division of Emergency Medicine, Children's Hospital Boston, Boston, MA 02115, USA. amir.kimia@childrens.harvard.edu
authors.forename: Amir
authors.initials: A
authors.lastname: Kimia
authors.forename: John S
authors.initials: JS
authors.lastname: Brownstein
authors.forename: Karen L
authors.initials: KL
authors.lastname: Olson
authors.forename: Victor
authors.initials: V
authors.lastname: Zak
authors.forename: Florence T
authors.initials: FT
authors.lastname: Bourgeois
authors.forename: Kenneth D
authors.initials: KD
authors.lastname: Mandl
mesh_terms: D000293:Adolescent; D000328:Adult; D017677:Age Distribution; D002648:Child; D002675:Child, Preschool; D015331:Cohort Studies; D004636:Emergency Service, Hospital / Q000706:statistics & numerical data*; D005260:Female; D006801:Humans; D007223:Infant; D007964:Leukocytosis / Q000134:cerebrospinal fluid / Q000453:epidemiology; D008297:Male; D008404:Massachusetts / Q000453:epidemiology; D009422:Nervous System Diseases / Q000134:cerebrospinal fluid / Q000453:epidemiology; D010372:Pediatrics / Q000706:statistics & numerical data*; D011159:Population Surveillance / Q000379:methods*; D010818:Practice Patterns, Physicians' / Q000706:statistics & numerical data*; D012189:Retrospective Studies; D012621:Seasons; D013129:Spinal Puncture / Q000706:statistics & numerical data*