title: Excess mortality associated with influenza A and B virus in Hong Kong, 1998-2009.
abstract: BACKGROUND
  Although deaths associated with laboratory-confirmed influenza virus infections are rare, the excess mortality burden of influenza estimated from statistical models may more reliably quantify the impact of influenza in a population.
  
  
  METHODS
  We applied age-specific multiple linear regression models to all-cause and cause-specific mortality rates in Hong Kong from 1998 through 2009. The differences between estimated mortality rates in the presence or absence of recorded influenza activity were used to estimate influenza-associated excess mortality.
  
  
  RESULTS
  The annual influenza-associated all-cause excess mortality rate was 11.1 (95% confidence interval [CI], 7.2-14.6) per 100,000 person-years. We estimated an average of 751 (95% CI, 488-990) excess deaths associated with influenza annually from 1998 through 2009, with 95% of the excess deaths occurring in persons aged ≥65 years. Most of the influenza-associated excess deaths were from respiratory (53%) and cardiovascular (18%) causes. Influenza A(H3N2) epidemics were associated with more excess deaths than influenza A(H1N1) or B during the study period.
  
  
  CONCLUSIONS
  Influenza was associated with a substantial number of excess deaths each year, mainly among the elderly, in Hong Kong in the past decade. The influenza-associated excess mortality rates were generally similar in Hong Kong and the United States.
authors.affiliation: School of Public Health, Li Ka Shing Faculty of Medicine,  University of Hong Kong, Hong Kong Special Administrative Region,  China.
authors.forename: Peng
authors.initials: P
authors.lastname: Wu
authors.forename: Edward
authors.initials: E
authors.lastname: Goldstein
authors.forename: Lai Ming
authors.initials: LM
authors.lastname: Ho
authors.forename: Lin
authors.initials: L
authors.lastname: Yang
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Nishiura
authors.forename: Joseph T
authors.initials: JT
authors.lastname: Wu
authors.forename: Dennis K M
authors.initials: DK
authors.lastname: Ip
authors.forename: Shuk-Kwan
authors.initials: SK
authors.lastname: Chuang
authors.forename: Thomas
authors.initials: T
authors.lastname: Tsang
authors.forename: Benjamin J
authors.initials: BJ
authors.lastname: Cowling
mesh_terms: D000293:Adolescent; D000328:Adult; D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D002648:Child; D002675:Child, Preschool; D005260:Female; D006723:Hong Kong / Q000453:epidemiology; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D009980:Influenza A virus / Q000302:isolation & purification / Q000472:pathogenicity*; D009981:Influenza B virus / Q000302:isolation & purification / Q000472:pathogenicity*; D007251:Influenza, Human / Q000453:epidemiology* / Q000401:mortality* / Q000821:virology; D008297:Male; D008875:Middle Aged; D009026:Mortality / Q000639:trends*; D014481:United States / Q000453:epidemiology; D055815:Young Adult