title: The burden of rotavirus gastroenteritis and hospital-acquired rotavirus gastroenteritis among children aged less than 6 years in Japan: a retrospective, multicenter epidemiological survey.
abstract: BACKGROUND
  Rotavirus is a leading worldwide cause of acute gastroenteritis in young children. This retrospective hospital-based study assessed the burden of rotavirus gastroenteritis in children younger than 6 years in Japan.
  
  
  METHODS
  Children admitted to eight hospitals for acute gastroenteritis between 2008 and 2009 were identified from hospital admission databases. Diagnosis of acute gastroenteritis/rotavirus gastroenteritis and hospital-acquired rotavirus gastroenteritis was confirmed based on either the International Classification of Diseases and Related Health Problems 10th revision (ICD10) codes (intestinal infectious diseases [AA00-AA09] and rotavirus gastroenteritis [A08.0]) or from rapid rotavirus diagnostic test results.
  
  
  RESULTS
  Of 13,767 hospitalized children, 11.9% (1,644), 4.8% (665) and 0.6% (81) were diagnosed with acute gastroenteritis, rotavirus gastroenteritis and hospital-acquired rotavirus gastroenteritis, respectively. Among acute gastroenteritis hospitalizations, 40.5% (665/1,644; ICD10 and rapid test) and 57.7% (645/1,118; rapid test only) were confirmed as rotavirus positive. Of 1,563 children with community-acquired acute gastroenteritis, 584 (37.4%) cases were confirmed as rotavirus positive. The median durations of hospitalization for all and community-acquired rotavirus gastroenteritis were 5.0 days (range: 2.0-133.0 days) and 5.0 days (range: 2.0-34.0 days), respectively. Among rotavirus gastroenteritis hospitalizations, 12.2% (81/665) of cases were hospital-acquired and the median duration of hospitalization was 10.0 days (range: 2.0-133.0 days). The median duration of additional hospitalization due to hospital-acquired rotavirus gastroenteritis was 3.0 days (range: 0-14 days). The overall incidence rate of hospital-acquired rotavirus gastroenteritis was 1.0 per 1,000 children hospital-days. The number of rotavirus gastroenteritis cases peaked between February and May in both 2008 and 2009, and the highest number of cases was reported in March 2008 (21.8%; 145/665). The highest number of rotavirus gastroenteritis hospitalizations (24.1%; 160/665) was observed in children aged 12-18 months. The proportion of hospital-acquired rotavirus gastroenteritis was higher in children aged below 18 months as compared to children at least 18 months of age (0.94 [95% CI: 0.71-1.21] vs. 0.39 [95% CI: 0.25-0.58]) and for children hospitalized for at least 5 days compared to those hospitalized for less than 5 days (0.91 [95% CI: 0.72-1.14] vs. 0.15 [95% CI: 0.05-0.32]).
  
  
  CONCLUSIONS
  Both community- and hospital-acquired rotavirus gastroenteritis are significant public health problems in Japan. Data from this study justify the need for the introduction and implementation of rotavirus vaccination in the Japanese national immunization program.
  
  
  BACKGROUND
  ClinicalTrials.gov, NCT01202201.
authors.affiliation: Osaka General Medical Center, 3-1-56, Mandai-Higashi, Sumiyoshi, Osaka 558-8558, Japan. tajiriji@gh.opho.jp
authors.forename: Hitoshi
authors.initials: H
authors.lastname: Tajiri
authors.forename: Yuriko
authors.initials: Y
authors.lastname: Takeuchi
authors.forename: Tomoko
authors.initials: T
authors.lastname: Takano
authors.forename: Toshihiro
authors.initials: T
authors.lastname: Ohura
authors.forename: Ayano
authors.initials: A
authors.lastname: Inui
authors.forename: Kimie
authors.initials: K
authors.lastname: Yamamoto
authors.forename: Yoshihito
authors.initials: Y
authors.lastname: Higashidate
authors.forename: Hisashi
authors.initials: H
authors.lastname: Kawashima
authors.forename: Shigeru
authors.initials: S
authors.lastname: Toyoda
authors.forename: Kosuke
authors.initials: K
authors.lastname: Ushijima
authors.forename: Gunasekaran
authors.initials: G
authors.lastname: Ramakrishnan
authors.forename: Mats
authors.initials: M
authors.lastname: Rosenlund
authors.forename: Katsiaryna
authors.initials: K
authors.lastname: Holl
mesh_terms: D000208:Acute Disease; D017677:Age Distribution; D002648:Child; D002675:Child, Preschool; D017714:Community-Acquired Infections / Q000175:diagnosis / Q000453:epidemiology; D017281:Cost of Illness; D003428:Cross Infection / Q000175:diagnosis / Q000453:epidemiology; D016208:Databases, Factual; D005260:Female; D005759:Gastroenteritis / Q000175:diagnosis / Q000453:epidemiology*; D006306:Health Surveys; D006760:Hospitalization / Q000706:statistics & numerical data; D006801:Humans; D015994:Incidence; D007223:Infant; D007231:Infant, Newborn; D007564:Japan / Q000453:epidemiology; D007902:Length of Stay / Q000706:statistics & numerical data; D008297:Male; D012189:Retrospective Studies; D012400:Rotavirus Infections / Q000175:diagnosis / Q000453:epidemiology*; D012621:Seasons