J.INF.DIS. Influenza Infection and Risk of Acute Myocardial Infarction in England and Wales: A CALIBER Self-Controlled Case Series Study

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J Infect Dis. (2012) doi: 10.1093/infdis/jis597 First published online: October 9, 2012



Influenza Infection and Risk of Acute Myocardial Infarction in England and Wales: A CALIBER Self-Controlled Case Series Study

Charlotte Warren-Gash1,
Andrew C. Hayward1,
Harry Hemingway2,
Spiros Denaxas2,
Sara L. Thomas3,
Adam D. Timmis5,
Heather Whitaker6 and
Liam Smeeth4

+ Author Affiliations

1Centre for Infectious Disease Epidemiology, Research Department of Infection & Population Health
2Department of Epidemiology & Public Health, University College London
3Department of Infectious Disease Epidemiology
4Department of Non-Communicable Disease Epidemiology, London School of Hygiene & Tropical Medicine
5Barts and the London School of Medicine and Dentistry, London
6Department of Mathematics & Statistics, Open University, Milton Keynes, United Kingdom

Correspondence: Charlotte Warren-Gash, MRCP, UCL Research Department of Infection & Population Health, Royal Free Hospital, Rowland Hill St, London NW3 2PF, United Kingdom (c.warren-gash@ucl.ac.uk).

Abstract

Background. An association between infections and vascular events has been observed, but the specific effect of influenza and influenza-like illnesses on triggering acute myocardial infarction (AMI) is unclear.

Methods. Episodes of first AMI from 1 January 2003 through 31 July 2009 were identified using linked anonymized electronic medical records from the Myocardial Ischaemia National Audit Project and the General Practice Research Database. Self-controlled case series analysis was used to investigate AMI risks after consultation for acute respiratory infection. Infections were stratified by influenza virus circulation, diagnostic code, and vaccination status to assess whether influenza was more likely than other infections to trigger AMI.

Results. Of 22 024 patients with acute coronary syndrome, 11 208 met the criterion of having had their first AMI at the age of ≥40 years, and 3927 had also consulted for acute respiratory infection. AMI risks were significantly raised during days 1?3 after acute respiratory infection (incidence ratio, 4.19 [95% confidence interval, 3.18?5.53], with the effect tapering over time. The effect was greatest in those aged ≥80 years (P = .023). Infections occurring when influenza was circulating and those coded as influenza-like illness were associated with consistently higher incidence ratios for AMI (P = .012).

Conclusions. Influenza and other acute respiratory infections can act as a trigger for AMI. This effect may be stronger for influenza than for other infections.

http://jid.oxfordjournals.org/content/early/2012/10/09/infdis.jis597.short

 

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Re: J.INF.DIS. Influenza Infection and Risk of Acute Myocardial Infarction in England and Wales: A CALIBER Self-Controlled Case Series Study

J Infect Dis. (2012) doi: 10.1093/infdis/jis598 First published online: October 9, 2012



Increasing Evidence That Influenza Is a Trigger for Cardiovascular Disease

A. Niroshan Siriwardena

+ Author Affiliations

Faculty of Health and Social Sciences, University of Lincoln, Lincoln, United Kingdom

Correspondence: A. Niroshan Siriwardena, PhD, Faculty of Health and Social Sciences, University of Lincoln, Brayford Campus, Lincoln, LN6 7TS, United Kingdom (nsiriwardena@lincoln.ac.uk).

Cardiovascular disease (CVD) is the cause of most premature deaths in more-developed countries. Although conventional risk factors account for much of the population attributable risk of CVD, they are less effective at predicting future cardiovascular events (ie, heart attack and stroke) in individuals since many people without CVD also have 1 or more risk factors present [1]. A possible explanation is the link between infection and atherosclerosis, first suggested a century ago by William Osler [2] and undergoing a resurgence of interest in recent times.

CVD is increasingly considered to be an inflammatory condition, and evidence is increasing that CVD may be triggered by infections. Initial interest in chronic bacterial infections, such as Chlamydia pneumoniaei, Helicobacter pylori, or dental infections [3?5], as potential precipitants of acute myocardial infarction (AMI) and stroke has diminished following negative findings from epidemiological studies [6] and therapeutic trials of antimicrobial agents [7?9]. The study by Warren-Gash and colleagues [10] published in this issue gives support to the hypothesis that acute respiratory infection, and particularly influenza, may be a trigger.

The authors used a self-controlled case series method [11] with a novel database (CALIBER) that links hospital data on acute myocardial infection (AMI) and general practice data, including patients presenting with acute respiratory infections. They investigated the risk and timing of first AMI with the timing of preceding acute respiratory infections (ARIs) in patients aged ≥40 years in this primary care population. ?


http://jid.oxfordjournals.org/content/early/2012/10/09/infdis.jis598.short