title: Trends in Respiratory Syncytial Virus and Bronchiolitis Hospitalization Rates in High-Risk Infants in a United States Nationally Representative Database, 1997-2012.
abstract: BACKGROUND
  Respiratory syncytial virus (RSV) causes significant pediatric morbidity and is the most common cause of bronchiolitis. Bronchiolitis hospitalizations declined among US infants from 2000‒2009; however, rates in infants at high risk for RSV have not been described. This study examined RSV and unspecified bronchiolitis (UB) hospitalization rates from 1997‒2012 among US high-risk infants.
  
  
  METHODS
  The Kids' Inpatient Database (KID) infant annual RSV (ICD-9 079.6, 466.11, 480.1) and UB (ICD-9 466.19, 466.1) hospitalization rates were estimated using weighted counts. Denominators were based on birth hospitalizations with conditions associated with high-risk for RSV: chronic perinatal respiratory disease (chronic lung disease [CLD]); congenital airway anomalies (CAA); congenital heart disease (CHD); Down syndrome (DS); and other genetic, metabolic, musculoskeletal, and immunodeficiency conditions. Preterm infants could not be identified. Hospitalizations were characterized by mechanical ventilation, inpatient mortality, length of stay, and total cost (2015$). Poisson and linear regression were used to test statistical significance of trends.
  
  
  RESULTS
  RSV and UB hospitalization rates were substantially elevated for infants with higher-risk CHD, CLD, CAA and DS without CHD compared with all infants. RSV rates declined by 47.0% in CLD and 49.7% in higher-risk CHD infants; no other declines in high-risk groups were observed. UB rates increased in all high-risk groups except for a 22.5% decrease among higher-risk CHD. Among high-risk infants, mechanical ventilation increased through 2012 to 20.4% and 13.5% of RSV and UB hospitalizations; geometric mean cost increased to $31,742 and $25,962, respectively, and RSV mortality declined to 0.9%.
  
  
  CONCLUSIONS
  Among high-risk infants between 1997 and 2012, RSV hospitalization rates declined among CLD and higher-risk CHD infants, coincident with widespread RSV immunoprophylaxis use in these populations. UB hospitalization rates increased in all high-risk groups except higher-risk CHD, suggesting improvement in the health status of higher-risk CHD infants, potentially due to enhanced surgical interventions. Mechanical ventilation use and RSV and UB hospitalization costs increased while RSV mortality declined.
authors.affiliation: Epidstat, Ann Arbor, MI, United States of America.
authors.forename: Abigail
authors.initials: A
authors.lastname: Doucette
authors.affiliation: Epidstat, Ann Arbor, MI, United States of America.
authors.forename: Xiaohui
authors.initials: X
authors.lastname: Jiang
authors.affiliation: Epidstat, Ann Arbor, MI, United States of America.
authors.forename: Jon
authors.initials: J
authors.lastname: Fryzek
authors.affiliation: Epidstat, Ann Arbor, MI, United States of America.
authors.forename: Jenna
authors.initials: J
authors.lastname: Coalson
authors.affiliation: AstraZeneca, Gaithersburg, MD, United States of America.
authors.forename: Kimmie
authors.initials: K
authors.lastname: McLaurin
authors.affiliation: AstraZeneca, Gaithersburg, MD, United States of America.
authors.forename: Christopher S
authors.initials: CS
authors.lastname: Ambrose
mesh_terms: D001988:Bronchiolitis / Q000453:epidemiology / Q000628:therapy*; D016208:Databases, Factual; D005260:Female; D006760:Hospitalization / Q000706:statistics & numerical data*; D006801:Humans; D007223:Infant; D008297:Male; D018357:Respiratory Syncytial Virus Infections / Q000453:epidemiology / Q000628:therapy*; D014481:United States / Q000453:epidemiology