Moderate drinking protects against some but not all heart disease

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Moderate drinking is associated with a lower risk of several – but not all – cardiovascular diseases, according to a large study of UK adults led by researchers at the University of Cambridge and University College London.

The finding that moderate drinking is not universally associated with a lower risk of all cardiovascular conditions suggests a more nuanced approach to the role of alcohol in prevention of cardiovascular disease is necessary, say the researchers. Moderate drinking is thought to be associated with a lower risk of developing cardiovascular disease compared with abstinence or heavy drinking.

In the UK, moderate drinking is defined as no more than 14 units of alcohol a week, the equivalent of 7 pints of ordinary strength beer or just over one and a half bottles of ordinary strength wine. There is, however, a growing scepticism around this observation, with some experts pointing out several shortcomings in the evidence, for example grouping non-drinkers with former drinkers, who may have stopped drinking due to poor health.

Researchers at the University of Cambridge and University College London set out to investigate the association between alcohol consumption and 12 cardiovascular diseases by analysing electronic health records for 1.93m healthy UK adults as part of the CALIBER (ClinicAl research using LInked Bespoke studies and Electronic health Records) data resource.

All participants were free from cardiovascular disease at the start of the study, and non-drinkers were separated from former and occasional drinkers to provide additional clarity in this debate.

The researchers looked at the effect of different levels of drinking on the risk of ‘first presenting’ to a doctor with a number of cardiovascular diseases; for example, did moderate drinking make it more or less likely that an individual’s first diagnosis of cardiovascular disease was a heart attack.

After several influential factors were accounted for, moderate drinking was associated with a lower risk of several, but not all, cardiovascular conditions, including angina, heart failure and ischaemic stroke (the most common type of stroke, when a blood clot blocks the flow of blood and oxygen to the brain), compared with abstaining from alcohol.

“This doesn’t mean that it is advisable for individuals to take up drinking as a means of lowering their cardiovascular risk,” says Dr Steven Bell from the department of public health and primary care at the University of Cambridge. “Alcohol consumption is associated with other diseases, such as liver disease and certain types of cancer. There are other, safer and more effective ways, such as being more physically active, maintaining a healthy diet and stopping smoking.

“Ultimately an individual’s decision to drink, and at what level, should not be considered in isolation of other health behaviours or risk factors and instead be motivated by their own personal circumstances.”

Heavy drinking (exceeding recommended limits) conferred an increased risk of a range of cardiovascular diseases, including heart failure, cardiac arrest (when the heart malfunctions and stops beating suddenly) and ischaemic stroke compared with moderate drinking. However, it carried a lower risk of heart attack (when blood flow to the heart is blocked) and angina.

Again, the authors explain that this does not mean that heavy drinkers will not go on to experience a heart attack in the future, just this was less likely to be their first diagnosis compared with moderate drinkers.

This is an observational study, so no firm conclusions can be drawn about cause and effect. Added to which, the authors point to some study limitations that could have introduced bias. Nevertheless, they say it is the first time this association has been investigated on such a large scale and their findings have implications for patient counselling, public health communication, and disease prediction tools.

In a linked editorial, researchers at Harvard Medical School and Johns Hopkins School of Public Health in the US say this study “sets the stage for ever larger and more sophisticated studies that will attempt to harness the flood of big data into a stream of useful, reliable, and unbiased findings that can inform public health, clinical care, and the direction of future research”.

Abstract
Objectives: To investigate the association between alcohol consumption and cardiovascular disease at higher resolution by examining the initial lifetime presentation of 12 cardiac, cerebrovascular, abdominal, or peripheral vascular diseases among five categories of consumption.
Design: Population based cohort study of linked electronic health records covering primary care, hospital admissions, and mortality in 1997-2010 (median follow-up six years).
Setting: CALIBER (ClinicAl research using LInked Bespoke studies and Electronic health Records).
Participants: 1 937 360 adults (51% women), aged ≥30 who were free from cardiovascular disease at baseline.
Main outcome measures: 12 common symptomatic manifestations of cardiovascular disease, including chronic stable angina, unstable angina, acute myocardial infarction, unheralded coronary heart disease death, heart failure, sudden coronary death/cardiac arrest, transient ischaemic attack, ischaemic stroke, intracerebral and subarachnoid haemorrhage, peripheral arterial disease, and abdominal aortic aneurysm.
Results: 114 859 individuals received an incident cardiovascular diagnosis during follow-up. Non-drinking was associated with an increased risk of unstable angina (hazard ratio 1.33, 95% confidence interval 1.21 to 1.45), myocardial infarction (1.32, 1.24 to1.41), unheralded coronary death (1.56, 1.38 to 1.76), heart failure (1.24, 1.11 to 1.38), ischaemic stroke (1.12, 1.01 to 1.24), peripheral arterial disease (1.22, 1.13 to 1.32), and abdominal aortic aneurysm (1.32, 1.17 to 1.49) compared with moderate drinking (consumption within contemporaneous UK weekly/daily guidelines of 21/3 and 14/2 units for men and women, respectively). Heavy drinking (exceeding guidelines) conferred an increased risk of presenting with unheralded coronary death (1.21, 1.08 to 1.35), heart failure (1.22, 1.08 to 1.37), cardiac arrest (1.50, 1.26 to 1.77), transient ischaemic attack (1.11, 1.02 to 1.37), ischaemic stroke (1.33, 1.09 to 1.63), intracerebral haemorrhage (1.37, 1.16 to 1.62), and peripheral arterial disease (1.35; 1.23 to 1.48), but a lower risk of myocardial infarction (0.88, 0.79 to 1.00) or stable angina (0.93, 0.86 to 1.00).
Conclusions: Heterogeneous associations exist between level of alcohol consumption and the initial presentation of cardiovascular diseases. This has implications for counselling patients, public health communication, and clinical research, suggesting a more nuanced approach to the role of alcohol in prevention of cardiovascular disease is necessary.

Authors
Steven Bell, Marina Daskalopoulou, Eleni Rapsomaniki, Julie George, Annie Britton, Martin Bobak, Juan P Casas, Caroline E Dale, Spiros Denaxas, Anoop D Shah, Harry Hemingway

University of Cambridge material BMJ abstract

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