Epidemiology and Infection

Original Papers

Influenza

Acute myocardial infarctions, strokes and influenza: seasonal and pandemic effects

E. D. FOSTERa1 c1, J. E. CAVANAUGHa1, W. G. HAYNESa2, M. YANGa1, A. K. GERKEa3, F. TANGa1 and P. M. POLGREENa4a5

a1 Department of Biostatistics, College of Public Health, University of Iowa, Iowa City, IA, USA

a2 General Clinical Research Center, Department of Internal Medicine, Carver College of Medicine, University of Iowa, Iowa City, IA, USA

a3 Division of Pulmonary and Critical Care, Department of Internal Medicine, University of Iowa, Iowa City, IA, USA

a4 Division of Infectious Diseases, Department of Internal Medicine, Carver College of Medicine, University of Iowa, Iowa City, IA, USA

a5 Department of Epidemiology, College of Public Health, University of Iowa, Iowa City, IA, USA

SUMMARY

The incidence of myocardial infarctions and influenza follow similar seasonal patterns. To determine if acute myocardial infarctions (AMIs) and ischaemic strokes are associated with influenza activity, we built time-series models using data from the Nationwide Inpatient Sample. In these models, we used influenza activity to predict the incidence of AMI and ischaemic stroke. We fitted national models as well as models based on four geographical regions and five age groups. Across all models, we found consistent significant associations between AMIs and influenza activity, but not between ischaemic strokes and influenza. Associations between influenza and AMI increased with age, were greatest in those aged >80 years, and were present in all geographical regions. In addition, the natural experiment provided by the second wave of the influenza pandemic in 2009 provided further evidence of the relationship between influenza and AMI, because both series peaked in the same non-winter month.

(Received June 05 2012)

(Revised November 02 2012)

(Accepted November 22 2012)

(Online publication January 03 2013)

Key words

  • Acute myocardial infarction;
  • influenza;
  • ischaemic stroke;
  • pandemic

Correspondence

c1 Author for correspondence: Mr E. D. Foster, Department of Biostatistics, College of Public Health, 105 River Street, The University of Iowa, Iowa City, IA 52242, USA. (Email: eric-foster@uiowa.edu)

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