title: A study of influenza and influenza-related complications among children in a large US health insurance plan database.
abstract: BACKGROUND
  Influenza places a substantial burden on the affected individual and society. While there are data available on the overall occurrence of influenza in children, less information is available on the differential impact of influenza on healthcare for previously healthy children and those at high risk of developing influenza-related complications.
  
  
  OBJECTIVE
  To compare the frequency of influenza-related complications in healthy and 'at-risk' children, and quantify the associated use of medical resources and costs.
  
  
  METHODS
  Data were obtained from a large US-based health insurance plan database.
  
  
  RESULTS
  A total of 23 188 health insurance claims with an influenza diagnosis were identified over the 3-year period 1995-1997 (3 247 834 patient-years). Influenza-related complications were observed in approximately a quarter of the total diagnosed cases, with younger children (0-4 years of age) at substantially greater risk. 'At-risk' children were more likely to develop influenza-related complications than otherwise healthy children. The greatest difference in incidence rate in the 0-4 year age group was for asthma (incidence rate ratio 8.7, 95% CI 5.2-14.4), and in the 5-14 year age group for asthma (incidence rate ratio 8.5, 95% CI 5.2-13.7) and acute sinusitis (incidence rate ratio 2.7, 95% CI 1.2-5.4). The average direct medical costs of influenza in children under 15 years with complications were more than 3.5 times higher than those without.
  
  
  CONCLUSIONS
  Measures to prevent and treat influenza-related complications are certainly warranted for at-risk children, although the elevated incidence rates for several common complications even among healthy children should prompt consideration of these measures for all children.
authors.affiliation: Ingenix Epidemiology Division, Newton, Massachusetts 02466, USA. jloughlin@epidemiology .com
authors.forename: Jeanne
authors.initials: J
authors.lastname: Loughlin
authors.forename: Nick
authors.initials: N
authors.lastname: Poulios
authors.forename: Pavel
authors.initials: P
authors.lastname: Napalkov
authors.forename: Yann
authors.initials: Y
authors.lastname: Wegmüller
authors.forename: Arnold S
authors.initials: AS
authors.lastname: Monto
mesh_terms: D000208:Acute Disease; D000293:Adolescent; D001249:Asthma / Q000188:drug therapy / Q000191:economics / Q000209:etiology; D002648:Child; D002675:Child, Preschool; D016208:Databases, Factual; D004180:Direct Service Costs; D006801:Humans; D015994:Incidence; D007223:Infant; D007231:Infant, Newborn; D007251:Influenza, Human / Q000150:complications* / Q000188:drug therapy / Q000191:economics*; D007348:Insurance, Health; D012189:Retrospective Studies; D012307:Risk Factors; D012852:Sinusitis / Q000188:drug therapy / Q000191:economics / Q000209:etiology; D014481:United States