Although other studies have already established a link between drinking alcohol and heart disease and premature death, the researchers wanted to look in more detail at the role of drinking patterns and type of alcohol. So they set up a study to investigate drinking habits in two culturally diverse countries.
They discovered that despite the fact middle-aged drinking men in Belfast consume on average about the same amount of alcohol per week as their counterparts in France, in Belfast they tend to consume it in one day (usually Saturday) at the weekend, whereas in France they drink it more evenly over the week.
They also found that a much higher proportion of middle aged male drinkers in France regularly drink alcohol at least once a week, and also have a higher average weekly consumption of alcohol per head, compared to their counterparts in Belfast; however, in Belfast they drink two to three times as much alcohol over the weekend as in France.
You can read about the study, which used data from the PRIME (short for Prospective Epidemiological Study of Myocardial Infarction) cohort, in the 23 November online issue of BMJ. The lead author was Dr Jean-Bernard Ruidavets from Toulouse University.
Using data obtained on enrollment in 1991, Ruidavets and colleagues assessed the alcohol consumption and drinking patterns of 9,778 men aged from 50 to 59, attending centres in three cities in France (Lille, Strasbourg and Toulouse, 7373 men) and Belfast (2405 men). The participants were free of heart disease at enrollment.
They divided the men into four groups: never drinkers, former drinkers, regular drinkers and binge drinkers.
From interviews, questionnaire responses and medical records, the researchers were able to assess drinking habits, such as volume and type of alcohol consumed weekly and daily, and cardiovascular risk factors such age, use of tobacco, physical activity, blood pressure, and waist size.
The researchers defined "binge drinking" as drinking more than 50 g of alcohol over a short period of time. Thus participants who reported regularly drinking four or five 125 ml glasses or more of wine or half pints of beer on a single day would be classed as binge drinkers.
After enrollment, the men were followed for 10 years, during which time all "hard" coronary events (ie incident myocardial infarction or heart attack and coronary death), and incident angina pectoris, were registered, allowing the researchers to use statistical tools to look for patterns between these events and the drinking habits assessed at the start of the study.
The results showed that:
- 60.6% (1456 men) of the participants in Belfast and 90.6% (6679) of those in France reported drinking alcohol at least once a week.
- However, only 12% of the drinkers (173 of 1456 men) in Belfast drank alcohol every day compared with 75% (5008 of 6679 men) in France.
- The mean alcohol consumption among drinkers in Belfast was 22.1g per day, compared with 32.8g per day in France.
- The prevalence of binge drinking was nearly 20 times higher in Belfast where 9.4% of the participants fell into this category compared with only 0.5% of those in France.
- 7.0% of all participants (683 men) experienced ischaemic heart disease events during the 10 year follow up.
- Of these events, 3.3% (322 incidents) were "hard" events (eg heart attack, death) and 3.7% (361 incidents) were angina events.
- Expressed in terms of hard coronary events per 1000 person years, for Belfast the incidence was 5.63 and for France it was 2.78 (95% confidence interval CI ranging from 4.69 to 6.69 and 2.41 to 3.2 respectively).
- Across all participants, after taking into account potential confounders like geographic centre and classic cardiovascular risk factors, the hazard ratio for hard coronary events (compared with regular drinkers) was 1.97 for binge drinkers, 2.03 for never drinkers, and 1.57 for former drinkers (95% CIs ranging from 1.21 to 3.22, 1.41 to 2.94, and 1.11 to 2.21 respectively: note hazard ratio of 2.0 equates to "twice as likely").
- Comparing Belfast and France, the hazard ratio for hard coronary events was 1.76 (95% CI 1.37 to 2.67) before and 1.09 (95% CI 0.79 to 1.50) after adjustment for alcohol patterns and wine drinking (suggesting it is these factors that make the difference to raising the risk).
- Looking at alcohol type, only wine drinking was linked to a lower risk of hard coronary events, regardless of country.
"Regular and moderate alcohol intake throughout the week, the typical pattern in middle aged men in France, is associated with a low risk of ischaemic heart disease, whereas the binge drinking pattern more prevalent in Belfast confers a higher risk. "
They wrote that "the prevalence of binge drinking, which doubled the risk of ischaemic heart disease compared with regular drinking, was almost 20 times higher in Belfast than in the French centres."
Another reason why heart disease risk is higher in Belfast could be because more people tend to drink beer and spirits than wine, wrote the researchers. In France wine is the preferred alcoholic beverage, and there is evidence that drinking moderate amounts can protect against heart disease.
They suggested these findings have important implications for public health, especially as there is evidence young people in Mediterranean countries are starting to take up binge drinking.
"The alcohol industry takes every opportunity to imbue alcohol consumption with the positive image, emphasising its beneficial effects on ischaemic heart disease risk, but people also need to be informed about the health consequences of heavy drinking," they wrote.
Annie Britton from University College London wrote in an editorial accompanying the paper that binge drinking is not just tied to a higher risk of heart disease but is also linked to other conditions like cirrhosis of the liver and several kinds of cancer, and it also causes social problems.
She said public health messages aimed at middle aged men should make it clear that the protective effects of alcohol may be lost if they binge drink, and they could be placing themselves at higher risk of heart attack.
For young people the message about the dangers of binge drinking should be different, said Britton, because at their age the heart risk is likely to be low anyway and they will be less concerned about it.
Young people are more likely to respond to "anti-binge drinking messages that focus on the risk of alcohol poisoning, injuries, assaults, and regretful risky sexual encounters," wrote Britton.
"Patterns of alcohol consumption and ischaemic heart disease in culturally divergent countries: the Prospective Epidemiological Study of Myocardial Infarction (PRIME)."
Jean-Bernard Ruidavets, Pierre Ducimetière, Alun Evans, Michèle Montaye, Bernadette Haas, Annie Bingham, John Yarnell, Philippe Amouyel, Dominique Arveiler, Frank Kee, Vanina Bongard, Jean Ferrières.
Written by: Catharine Paddock, PhD