title: Differences in clinical manifestations of influenza-associated encephalopathy by age.
abstract: Data from patients in Japan was analyzed to examine the age distribution and differences by age in the clinical manifestations of influenza-associated encephalopathy. Between 1998 and 2002, 472 cases of influenza-associated encephalopathy in patients aged 15 years or younger were reported to the Collaborative Study Group on Influenza-Associated Encephalopathy. These cases were divided into two groups by age: 0-5 and 6-15 years. The differences between the groups were estimated based on the data for those aged 0-5 years, and the odds ratios and 95% confidence intervals calculated. Distribution was inversely correlated with age, with a peak at 1-2 years old. In comparison with patients aged 0-5, those aged 6-15 years had a significantly greater incidence of type B infection, lower frequency of convulsions, higher frequency of loss of consciousness and altered consciousness as the initial neurological symptom, lower serum transaminase levels, lower frequency of low-density area for brain CT upon admission, and lower incidence of sequelae. Our analysis indicates that the clinical course, laboratory data, and brain imaging findings of influenza-associated encephalopathy exhibits patterns that vary with age.
authors.affiliation: Department of Pediatrics, Okayama University, Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, 2-5-1 Shikata-cho, Okayama 700-8558, Japan.
authors.forename: Tomoaki
authors.initials: T
authors.lastname: Wada
authors.forename: Tsuneo
authors.initials: T
authors.lastname: Morishima
authors.forename: Akihisa
authors.initials: A
authors.lastname: Okumura
authors.forename: Masato
authors.initials: M
authors.lastname: Tashiro
authors.forename: Mitsuaki
authors.initials: M
authors.lastname: Hosoya
authors.forename: Masashi
authors.initials: M
authors.lastname: Shiomi
authors.forename: Yoshinobu
authors.initials: Y
authors.lastname: Okuno
mesh_terms: D000293:Adolescent; D017677:Age Distribution; D002648:Child; D002675:Child, Preschool; D018792:Encephalitis, Viral / Q000453:epidemiology / Q000209:etiology*; D005260:Female; D006801:Humans; D015994:Incidence; D007223:Infant; D007251:Influenza, Human / Q000150:complications* / Q000453:epidemiology / Q000401:mortality; D007564:Japan / Q000453:epidemiology; D008297:Male