The role of influenza as a trigger for acute myocardial infarction
Lead Research Organisation:
University College London
Department Name: Immunology and Molecular Pathology
Abstract
Influenza (flu) is one of many viruses that cause respiratory symptoms in winter. In most people flu is a mild illness that may result in a trip to the GP or time off work. In the elderly and other vulnerable people, flu may cause a serious or even life-threatening respiratory illness. Now new evidence suggests that some respiratory infections may trigger other more serious conditions such as heart attacks. We do not yet know if this is true for flu. If it is, flu may be more dangerous than previously believed for people at risk from heart attacks such as smokers or those with high blood pressure.
We will study whether flu triggers heart attacks and, if so, how often this happens. We will look at whether vaccinating people against influenza also protects them from heart attacks. To do this we will analyse medical records from a large general practice database as well as studying recent influenza infection in patients hospitalised for heart attacks.
If flu does trigger heart attacks then we may be able to prevent some of these, either by vaccinating more people against flu or by treating people with antiviral drugs when they develop a flu-like illness.
We will study whether flu triggers heart attacks and, if so, how often this happens. We will look at whether vaccinating people against influenza also protects them from heart attacks. To do this we will analyse medical records from a large general practice database as well as studying recent influenza infection in patients hospitalised for heart attacks.
If flu does trigger heart attacks then we may be able to prevent some of these, either by vaccinating more people against flu or by treating people with antiviral drugs when they develop a flu-like illness.
Technical Summary
The role of influenza as a trigger for acute myocardial infarction
Background Recent evidence suggests that acute respiratory infections may trigger acute myocardial infarction (MI). However few studies examine whether influenza, rather than general respiratory infections, specifically triggers MI. Existing studies are limited by diagnostic misclassification, underestimation of the community burden of respiratory illness and problems caused by residual confounding. Larger studies are needed using different study designs in different populations to overcome these weaknesses.
Aims & Objectives This research aims to investigate the role of influenza as a trigger for MI, to determine the burden of MI attributable to influenza and to examine whether influenza vaccination protects against MI. The fellowship will provide training in clinical, epidemiological and statistical research methods relevant to the epidemiology, detection, impact and control of a specific communicable disease.
Design 1) Self-controlled case series analysis of influenza-like illness (ILI) in patients experiencing MI using national primary care data. 2) Case control study of serologically-confirmed influenza and recent ILI in patients hospitalised for MI.
Methodology
Self-controlled case series study Primary care records from The Health Improvement Network (THIN) will be used in conjunction with national surveillance data on ILI and virological investigation of ILI. Cases: all patients with acute MI diagnosed in the influenza season (1st Oct- 1st Apr). Relative incidence of MI in the 28 days after ILI will be compared to baseline risk periods for each individual. Statistical models will include levels of influenza activity and influenza vaccination status as parameters.
Case control study Cases: patients hospitalised for acute MI during the influenza season. Controls: patients hospitalised for acute surgical conditions with no recent history of MI, frequency matched for gender. I will collect demographic and clinical information by computer-assisted interview and obtain a blood sample for detection of influenza antibodies from all patients. Multiple logistic regression models will be used to examine the relationship between recent ILI or serologically confirmed influenza and MI.
Scientific and medical opportunities Cardiovascular disease - predominantly due to MI - is the UK‘s leading cause of death. Influenza is very common even in a low prevalence influenza season. If influenza triggers MI, many MIs may be prevented through widening indications for influenza vaccination or treating influenza cases promptly with antivirals. This has implications for health in both the UK and developing countries where access to cardiology services is often limited.
Background Recent evidence suggests that acute respiratory infections may trigger acute myocardial infarction (MI). However few studies examine whether influenza, rather than general respiratory infections, specifically triggers MI. Existing studies are limited by diagnostic misclassification, underestimation of the community burden of respiratory illness and problems caused by residual confounding. Larger studies are needed using different study designs in different populations to overcome these weaknesses.
Aims & Objectives This research aims to investigate the role of influenza as a trigger for MI, to determine the burden of MI attributable to influenza and to examine whether influenza vaccination protects against MI. The fellowship will provide training in clinical, epidemiological and statistical research methods relevant to the epidemiology, detection, impact and control of a specific communicable disease.
Design 1) Self-controlled case series analysis of influenza-like illness (ILI) in patients experiencing MI using national primary care data. 2) Case control study of serologically-confirmed influenza and recent ILI in patients hospitalised for MI.
Methodology
Self-controlled case series study Primary care records from The Health Improvement Network (THIN) will be used in conjunction with national surveillance data on ILI and virological investigation of ILI. Cases: all patients with acute MI diagnosed in the influenza season (1st Oct- 1st Apr). Relative incidence of MI in the 28 days after ILI will be compared to baseline risk periods for each individual. Statistical models will include levels of influenza activity and influenza vaccination status as parameters.
Case control study Cases: patients hospitalised for acute MI during the influenza season. Controls: patients hospitalised for acute surgical conditions with no recent history of MI, frequency matched for gender. I will collect demographic and clinical information by computer-assisted interview and obtain a blood sample for detection of influenza antibodies from all patients. Multiple logistic regression models will be used to examine the relationship between recent ILI or serologically confirmed influenza and MI.
Scientific and medical opportunities Cardiovascular disease - predominantly due to MI - is the UK‘s leading cause of death. Influenza is very common even in a low prevalence influenza season. If influenza triggers MI, many MIs may be prevented through widening indications for influenza vaccination or treating influenza cases promptly with antivirals. This has implications for health in both the UK and developing countries where access to cardiology services is often limited.
