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

Influenza Other Respir Viruses. 2013 Jul;7(4):531-9. doi: 10.1111/j.1750-2659.2012.00411.x. Epub 2012 Jul 20.


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.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Aged
  • Aged, 80 and over
  • Cohort Studies
  • Female
  • Hong Kong
  • Humans
  • Influenza, Human / mortality*
  • Male
  • Risk Factors
  • Smoking / adverse effects*
  • Survival Analysis