title: Using billing data to describe patterns in asthma-related emergency department visits in children.
abstract: OBJECTIVE
  To describe the development and evaluation of a pilot emergency department (ED)-based asthma surveillance system for childhood asthma visits based on billing data and to illustrate how the data can be used to document trends and patterns in ED visits for asthma in children.
  
  
  METHODS
  During 2001 and 2002, aggregate reports based on ED billing data from 3 hospitals in western Michigan were obtained from a single physician billing company. Data were tabulated and graphed to show trends in the monthly number of ED visits for asthma in children. Comparisons were made by age, gender, and site. We evaluated the system by using established guidelines.
  
  
  RESULTS
  The data illustrated strong seasonal trends, as well as marked differences in ED use according to age and gender. The total numbers of asthma ED visits were remarkably similar between the 2 years evaluated; however, the timing and duration of the seasonal peaks differed. Our evaluation of the system found that it met many of the characteristics that define successful surveillance systems, including simplicity, flexibility, acceptability, sensitivity and positive predictive value, timeliness, and stability. However, the surveillance system's representativeness was limited by the inability to calculate valid population-based ED-visit rates. Despite this limitation, the data provided useful information by documenting the burden and demographic profile of children who use the ED for asthma care and in identifying seasonal and time-related trends.
  
  
  CONCLUSIONS
  We were able to successfully implement a pilot ED-based surveillance system for childhood asthma visits by using billing data. This system promotes the understanding of the burden of asthma among children visiting the ED. The development of an ED-based surveillance system for childhood asthma visits using billing data is recommended, particularly when there is a desire to understand the characteristics of children with asthma who use the ED and/or a need to understand the impact of local asthma quality-improvement programs.
authors.affiliation: Department of Epidemiology, B 601 West Fee Hall, College of Human Medicine, Michigan State University, East Lansing, Michigan 48824, USA. reevesm@msu.edu
authors.forename: Mathew J
authors.initials: MJ
authors.lastname: Reeves
authors.forename: Sarah
authors.initials: S
authors.lastname: Lyon-Callo
authors.forename: Michael D
authors.initials: MD
authors.lastname: Brown
authors.forename: Ken
authors.initials: K
authors.lastname: Rosenman
authors.forename: Elizabeth
authors.initials: E
authors.lastname: Wasilevich
authors.forename: Seymour G
authors.initials: SG
authors.lastname: Williams
mesh_terms: D000293:Adolescent; D001249:Asthma / Q000191:economics* / Q000453:epidemiology* / Q000628:therapy; D002648:Child; D002662:Child Health Services / Q000191:economics / Q000706:statistics & numerical data*; D002675:Child, Preschool; D017281:Cost of Illness; D004636:Emergency Service, Hospital / Q000191:economics / Q000706:statistics & numerical data*; D005260:Female; D017722:Hospital Charges; D006801:Humans; D008297:Male; D008824:Michigan / Q000453:epidemiology; D010350:Patient Credit and Collection / Q000706:statistics & numerical data*; D010865:Pilot Projects; D011159:Population Surveillance / Q000379:methods*; D012621:Seasons