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. 2011 Jun 15;203(12):1710-8.
doi: 10.1093/infdis/jir171.

Circulating influenza virus, climatic factors, and acute myocardial infarction: a time series study in England and Wales and Hong Kong

Charlotte Warren-Gash  1 , Krishnan Bhaskaran, Andrew Hayward, Gabriel M Leung, Su-Vui Lo, Chit-Ming Wong, Joanna Ellis, Richard Pebody, Liam Smeeth, Benjamin J Cowling
Affiliations

Circulating influenza virus, climatic factors, and acute myocardial infarction: a time series study in England and Wales and Hong Kong

Charlotte Warren-Gash et al. J Infect Dis. .

Abstract

Background: Previous studies identifying associations between influenza and acute cardiac events may have been confounded by climatic factors. Differing seasonal patterns of influenza activity in Hong Kong and England and Wales provide a natural experiment to examine associations with myocardial infarction (MI) independent of cold weather effects.

Methods: Weekly clinical and laboratory influenza surveillance data, environmental temperature and humidity data, and counts of MI-associated hospitalizations and deaths were obtained for England and Wales and for Hong Kong for the period 1998-2008. We used Poisson regression models that included environmental and seasonal variables to investigate the relationship between influenza and MI.

Results: There were ≥1.2 million MI-associated hospitalizations and 410,204 MI-associated deaths in England and Wales, with a marked peak in the winter season. In Hong Kong, the incidence of MI, on the basis of 65,108 hospitalizations and 18,780 deaths, had a large winter and smaller summer peak, mirroring patterns of influenza activity. There was strong evidence for a link between influenza and MI both in England and Wales, where 3.1%-3.4% of MI-associated deaths (P < .001) and 0.7%-1.2% of MI-associated hospitalizations (P < .001) were attributable to influenza, and in Hong Kong, where the corresponding figures were 3.9%-5.6% (P = .018) and 3.0%-3.3% (P = .002).

Conclusions: Influenza was associated with an increase in MI-associated deaths and hospitalizations in 2 contrasting settings.

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Figures

Figure 1.
Figure 1.
Weekly general practitioner (GP) consultation rates for influenza-like illness and percentage of positive specimens. SARS, severe acute respiratory syndrome.
Figure 2.
Figure 2.
Schematic illustration of the interpretation of lag times in the analysis of associations between myocardial infarction (MI)–associated death and influenza-like illness (ILI) consultations. For example in the analysis with a lag time of −1 week, MI-associated deaths in week 1 are correlated with ILI consultations in week 2, etc.
Figure 3.
Figure 3.
Weekly influenza circulation and number of myocardial infarction (MI)–associated deaths. ILI, influenza-like illness.
See this image and copyright information in PMC

Comment in

References

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