title: Syndromic surveillance using ambulatory electronic health records.
abstract: OBJECTIVE
  To assess the performance of electronic health record data for syndromic surveillance and to assess the feasibility of broadly distributed surveillance.
  
  
  METHODS
  Two systems were developed to identify influenza-like illness and gastrointestinal infectious disease in ambulatory electronic health record data from a network of community health centers. The first system used queries on structured data and was designed for this specific electronic health record. The second used natural language processing of narrative data, but its queries were developed independently from this health record. Both were compared to influenza isolates and to a verified emergency department chief complaint surveillance system.
  
  
  METHODS
  Lagged cross-correlation and graphs of the three time series.
  
  
  RESULTS
  For influenza-like illness, both the structured and narrative data correlated well with the influenza isolates and with the emergency department data, achieving cross-correlations of 0.89 (structured) and 0.84 (narrative) for isolates and 0.93 and 0.89 for emergency department data, and having similar peaks during influenza season. For gastrointestinal infectious disease, the structured data correlated fairly well with the emergency department data (0.81) with a similar peak, but the narrative data correlated less well (0.47).
  
  
  CONCLUSIONS
  It is feasible to use electronic health records for syndromic surveillance. The structured data performed best but required knowledge engineering to match the health record data to the queries. The narrative data illustrated the potential performance of a broadly disseminated system and achieved mixed results.
authors.affiliation: Department of Biomedical Informatics, Columbia University, New York, NY, 10032, USA. hripcsak@columbia.edu
authors.forename: George
authors.initials: G
authors.lastname: Hripcsak
authors.forename: Nicholas D
authors.initials: ND
authors.lastname: Soulakis
authors.forename: Li
authors.initials: L
authors.lastname: Li
authors.forename: Frances P
authors.initials: FP
authors.lastname: Morrison
authors.forename: Albert M
authors.initials: AM
authors.lastname: Lai
authors.forename: Carol
authors.initials: C
authors.lastname: Friedman
authors.forename: Neil S
authors.initials: NS
authors.lastname: Calman
authors.forename: Farzad
authors.initials: F
authors.lastname: Mostashari
mesh_terms: D000554:Ambulatory Care Facilities / Q000706:statistics & numerical data; D004196:Disease Outbreaks; D004636:Emergency Service, Hospital / Q000706:statistics & numerical data; D005767:Gastrointestinal Diseases / Q000453:epidemiology; D006801:Humans; D007251:Influenza, Human / Q000453:epidemiology; D016347:Medical Records Systems, Computerized; D011159:Population Surveillance / Q000379:methods*; D040442:Public Health Informatics