Cigarette smoking as a risk factor for influenza-associated mortality: Evidence from an elderly cohort

Chit M. Wong, Lin Yang, King P. Chan, Wai M. Chan, Liang Song, Hak K. Lai, Thuan Q. Thach, Lai M. Ho, Kwok H. Chan, Tai H. Lam, Joseph S.M. Peiris

Research output: Journal article publicationJournal articleAcademic researchpeer-review

25 Citations (Scopus)

Abstract

Background The effects of individual lifestyle factors on the mortality risk after influenza infection have not been explored. Objectives In this study, we assessed the modifying effects of cigarette smoking on mortality risks associated with influenza in a cohort of Hong Kong elders with a follow-up period of 1998-2009. Methods We used the Cox proportional hazards model with time-dependent covariates of weekly proportions of specimens positive for influenza (termed as influenza virus activity), to calculate the hazard ratio of mortality associated with a 10% increase in influenza virus activity for never, ex- and current smokers. Other individual lifestyle and socioeconomic factors as well as seasonal confounders were also added into the models. Results The overall hazard ratio associated with influenza was 1·028 (95% confidence interval, 1·006, 1·051) for all natural cause mortality and 1·035 (1·003, 1·068) for cardiovascular and respiratory mortality. We found that influenza-associated hazard ratio was greater in current and ex-smokers than in never smokers for mortality of all natural causes, cardiovascular and respiratory diseases. Conclusions The findings suggest that smoking might increase influenza-associated mortality risks among elders.
Original languageEnglish
Pages (from-to)531-539
Number of pages9
JournalInfluenza and other Respiratory Viruses
Volume7
Issue number4
DOIs
Publication statusPublished - 1 Jul 2013
Externally publishedYes

Keywords

  • Cohort
  • Cox model
  • Influenza
  • Mortality
  • Smoking

ASJC Scopus subject areas

  • Epidemiology
  • Pulmonary and Respiratory Medicine
  • Public Health, Environmental and Occupational Health
  • Infectious Diseases

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