title: Burden of influenza-related hospitalizations among children with sickle cell disease.
abstract: OBJECTIVE
  Children with sickle cell disease (SCD) are considered to be at high risk for complications from influenza infection despite minimal published data that characterize the burden of influenza in this population. Our objectives were to (1) estimate the rate of influenza-related hospitalizations (IRHs) among children with SCD, (2) compare this rate with rates of children with cystic fibrosis (CF) and children with neither SCD nor CF, and (3) explore mechanisms that underlie these potentially preventable hospitalizations.
  
  
  METHODS
  We analyzed hospitalizations from 4 states (California, Florida, Maryland, and New York) across 2 influenza seasons (2003-2004 and 2004-2005) from the Healthcare Cost and Utilization Project State Inpatient Databases. We included hospitalizations with a discharge diagnosis code for influenza in a child <18 years of age. We used census data and disease prevalence estimates to calculate denominators and compare rates of IRH among children with SCD, CF, and neither disease.
  
  
  RESULTS
  There were 7896 pediatric IRHs during the 2 influenza seasons. Of these, 159 (2.0%) included a co-occurring diagnosis of SCD. Annual rates of IRHs were 112 and 2.0 per 10 000 children with and without SCD, respectively, across both seasons. Children with SCD were hospitalized with influenza at 56 times (95% confidence interval: 48-65) the rate of children without SCD. Children with SCD had approximately double the risk of IRH compared with children with CF (risk ratio: 2.1 [95% confidence interval: 1.5-2.9]). IRHs among children with SCD were not longer, more costly, or more severe than IRHs among children without SCD; they were also rarely nosocomial and co-occurred with a diagnosis of asthma in 14% of cases.
  
  
  CONCLUSIONS
  IRHs are substantially more common among children with SCD than among those without the disease, which supports the potential importance of vigorous influenza vaccination efforts that target children with SCD.
authors.affiliation: Johns Hopkins University School of Medicine, 600 N Wolfe St, CMSC 2-121, Baltimore, MD 21287, USA. dbundy@jhmi.edu
authors.forename: David G
authors.initials: DG
authors.lastname: Bundy
authors.forename: John J
authors.initials: JJ
authors.lastname: Strouse
authors.forename: James F
authors.initials: JF
authors.lastname: Casella
authors.forename: Marlene R
authors.initials: MR
authors.lastname: Miller
mesh_terms: D000293:Adolescent; D000755:Anemia, Sickle Cell / Q000453:epidemiology*; D002648:Child; D002675:Child, Preschool; D015897:Comorbidity; D017281:Cost of Illness; D003550:Cystic Fibrosis / Q000453:epidemiology; D005260:Female; D006760:Hospitalization / Q000706:statistics & numerical data*; D006801:Humans; D007223:Infant; D007251:Influenza, Human / Q000453:epidemiology*; D008297:Male; D014481:United States / Q000453:epidemiology