SIGN 97: Risk estimation and the prevention of cardiovascular disease

Guideline Index Page | SIGN Methodology

7 Alcohol

7.1 Alcohol and cardiovascular risk

Alcohol is known to have both beneficial and harmful effects on the biochemical basis for CHD and the psychological consequences of the disease.142

In Scotland, 32% of men and 14% of women drink above weekly recommended limits. Patterns of drinking vary and 44% of men who had drunk in the last week consumed eight units or more on their heaviest drinking day (where one unit is defined as approximately 8 g /10 ml of alcohol), indicating that binge drinking may be a particular problem.143 Evidence level 3

The adverse effects of alcohol on other clinical conditions (eg mental health, liver disease, cancer risk and societal effects) have not been reviewed in this guideline and should be taken into account when advice is provided in the clinical setting. Long term alcohol related health consequences are now giving rise to serious concerns in Scotland.

Consuming over 40 g/day alcohol increases a man?s risk for liver disease, raised blood pressure, some cancers (for which smoking is a confounding factor) and violent death. For women, consuming over 24 g/day average alcohol increases their risk for developing liver disease and breast cancer.144 Evidence level 4

7.1.1 How do alcohol consumption levels alter cardiovascular disease mortality and morbidity?

Systematic reviews of cohort and case control studies, show a ?J? shaped relationship between alcohol consumption and either vascular145 or CHD risk146-148 of mortality and morbidity. Most studies report data for middle-aged men. Where data is reported for subgroups of men and women, the maximum benefit for men is at 25 g alcohol per day (equivalent to three units/day), with some protection up to 87 g/day (equivalent to just under 9 units/day), and the maximum benefit for women is at 10 g/day (equivalent to approximately one unit/day), with some protection at up to 31 g/day (equivalent to approximately 4 units/day). The degree of reduction in risk of coronary events following light or moderate drinking is small but significant (RR=0.80, 95% CI 0.78 to 0.83).146 This is supported by some evidence of improved lipid profiles with regular drinking in moderation.146,149 Conversely, binge drinking is harmful and associated with a poorer lipid profile, and adverse effect on systolic blood pressure and increased risk of thrombosis.149,150 There does not appear to be any differential effect associated with type of alcohol consumed.145,151 Evidence level 2++, 2+, 4

It has been suggested that the apparent cardioprotective effect of alcohol may be accounted for by methodological flaws in the evidence. There may be a bias towards the publication of studies which identify a benefit, suggesting that intakes lower than the maximum reported may be optimal.146 Abstainers may have higher rates of pre-existing ill health, which would result in a relatively poorer outcome in comparative studies with alcohol drinkers.152 However, there is broad consistency of findings across systematic reviews, and with other guidelines.29,153,154 Evidence level 2++, 4

BPatients with no evidence of coronary heart disease may be advised that light to moderate alcohol consumption may be protective against the development of coronary heart disease.

Two cohort studies, which were nested within high quality RCTs, of the effects of alcohol consumption in secondary prevention subgroups confirmed the protective effective of moderate drinking.155,156 Evidence level 2+

CPatients with established coronary heart disease may be advised that light to moderate alcohol consumption may be protective against further coronary events.

[Good practice point] When giving advice to patients with coronary heart disease, the current general advice of no more than two to three units of alcohol per day for women and no more than three to four units of alcohol per day for men, with at least two drink-free days per week for both men and women, should be recommended.157,158

There is considerable confusion over the definition of a standard ?unit? of alcohol. One unit of alcohol in the UK means a beverage containing 8 g or 10 ml of ethanol. The amount of alcohol in units is calculated as: volume of drink (litres) x percentage by volume alcohol.144 There is a commonly held belief that half a pint of beer, or one glass of wine equate to a unit, but exact strength and volume are critical, as the examples in Table 5 illustrate. Standard pub measures are often smaller than drinks poured at home.

Table 5: Volumes of drinks equivalent to one unit of alcohol

Drink Percentage alcohol Volume equivalent to one unit
Beer/lager 3.5% 0.5 pint
Beer/lager 5.0% 0.35 pint
Wine 10% 100 ml (one 750 ml bottle = 7.5 units)
Wine 13% 77 ml (one 750 ml bottle = 9.75 units)
Fortified wine/sherry 17.5% 57.1 ml
Spirits 40% 25 ml

[Good practice point] Examples of what constitutes a ?drink? or unit of alcohol should be given to the patient.

7.1.2 What is the best way to modify alcohol consumption?

Three systematic reviews consider methods of reducing alcohol intake in those whose drinking is considered to be harmful or risky.159-161 All conclude that brief interventions are the most effective method with increased benefit from multi-contact interventions. One review concluded that for benefit an intervention had to include two of the three key elements: feedback, advice and goal setting.160 Many of the individual studies included in the reviews were not UK-based and some reviews included interventions which may not be deliverable in primary care in the UK (eg electric aversion therapy). Evidence level 1++, 1+, 2++

Brief interventions may include some of the following: information, feedback and advice on prevalence of drinking, adverse effects of alcohol, drinking cues, drinking diaries, drinking agreement/contract, retrospective self report of drinking alcohol or current alcohol qualities and types of alcohol consumed, injuries, healthcare utilisation, recommended levels of alcohol consumption, education on risks involved in consumption of alcohol, strategies for changing drinking habits, feedback of personal health data.162,163

There are a range of suggested time scales for brief interventions from five minutes to 20 minutes, from a single occasion up to five sessions, and vary from face to face to via the telephone.

A single RCT in subjects with type 2 diabetes and/or hypertension confirmed the benefit of multi- contact, brief counselling to reduce alcohol consumption in high risk patients (11% absolute reduction in numbers of heavy drinkers in intervention group).162 Evidence level 1++

One review specifically looked at the effectiveness of untargeted screening prior to delivering a brief intervention to modify alcohol consumption.163 It found that of 1,000 patients 90 screened positive, 25 of whom qualified for a brief intervention. At one year, two or three of these would have reduced their drinking to within the recommended alcohol intake levels. Evidence level 1+

ABrief multi-contact interventions should be used to encourage patients to reduce their levels of drinking if their current intake is hazardous to their health.

[Good practice point] Universal screening as a case-finding exercise in primary care is not recommended.

SIGN guideline 74 provides detailed guidance on managing harmful drinking and alcohol dependence alcohol consumption in primary care.144 Evidence level 4

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