Guideline 1: How the guideline is measured
Guideline 1 in the Australian guidelines to reduce health risks from drinking alcohol (NHMRC 2020) is:
To reduce the risk of harm from alcohol-related disease or injury, healthy men and women should drink no more than 10 standard drinks a week and no more than 4 standard drinks on any one day. The less you drink, the lower your risk of harm from alcohol.
This guideline contains two recommendations: not to consume more than 10 standard drinks per week and not to consume more than 4 standard drinks on any single day. Exceeding either of these recommendations results in an increased risk of alcohol-related disease or injury, so the method for measuring each recommendation must be defined separately.
Recommendation 1: 10 standard drinks a week
The 10 standard drinks per week recommendation defines an average weekly threshold. To assess the recommendation, survey questions must be able to estimate the average number of standard drinks a person consumes each week.
The NDSHS contains several questions which ask about patterns of drinking over the past 12 months, including quantity-frequency measures, captured by the following 2 questions:
- In the last 12 months, how often did you have an alcohol drink of any kind?
- On a day that you have an alcohol drink, how many standard drinks do you usually have?
And graduated quantity-frequency measures, captured by the following question:
- Please record how often in the last 12 months you have had each of the following number of standard drinks in a day:
- 20 or more standard drinks a day
- 11–19 standard drinks a day
- 7–10 standard drinks a day
- 5–6 standard drinks a day
- 3–4 standard drinks a day
- 1–2 standard drinks a day
- Some alcohol but less than 1 standard drink a day
- None i.e. no alcohol in a day.
Both measures are asked of all respondents (Australian residents aged 14 and over). Each respondent’s annual alcohol consumption can be estimated either by the quantity-frequency measures or the graduated quantity-frequency measures. This is typically done by totalling the number of standard drinks consumed by a person over the last 12 months, and then dividing it by 52.143 to obtain an average weekly amount of alcohol consumed. If this results in an average weekly consumption of more than 10 standard drinks (for either the quantity-frequency or the graduated quantity-frequency measure), then the respondent is considered to have consumed alcohol at levels that increased their risk of harm above 1 in 100 (Supplementary table G3).
Recommendation 2: 4 standard drinks on any one day
Both the quantity-frequency and graduated quantity-frequency measures in the NDSHS include categories above and below the 4 standard drink threshold, so it is possible to identify responses where respondents have consumed more than that in a single day, as well as how often they did so (typically reported as daily, weekly, monthly or yearly).
Combining both recommendations into a single estimate for drinking that reduces health risks from drinking alcohol
With different frequencies of exceeding 4 drinks in a single day, a single frequency measurement must be chosen for the measurement of guideline 1. Recommendation 1 is calculated across an entire year to estimate whether a respondent has consumed alcohol in ways that increased their risk of harm over a 12 month period. The second recommendation should similarly look at regular drinking behaviour that exceeds the 4 standard drinks in a day recommendation over a 12 month period (Supplementary table G4).
Including people in guideline 1 who have consumed more than 4 standard drinks on any one day in the previous year creates a large disparity between people consuming an average of more than 10 standard drinks per week (i.e. over 500 standard drinks across the year, with an increased chance of dying due to alcohol-related disease or injury) and people who have consumed more than 4 standard drinks once or twice throughout the year (and who had an increased risk of alcohol-related illness or injury during those occasions).
Initial results for risky drinking patterns according to guideline 1 were explored by examining two different frequencies of consuming more than 4 standard drinks in a single day:
- Once per week (to align with the weekly timeframe of the 10 standard drinks recommendation); and
- Once per month (which was the typical frequency that AIHW reported for “single occasion risk” from 2010 to 2019, following the previous iteration of the Australian alcohol guidelines (NHMRC 2009)).
For each survey wave between 2001 and 2019, the difference between the ‘once a week’ and ‘once a month’ definitions was 6–7 percentage points but the overall trend was the same. This indicates that the choice of frequency does not impact on trends for risky drinking but does have an effect on the overall prevalence rate.
After consultation with the NHMRC, it was advised that the ‘once a month’ definition should be used. This has the benefit of being consistent with previous AIHW reporting on alcohol risk, and also captures patterns of risky drinking (such as binge drinking) that may occur frequently, but not as often as weekly (for example, with a person’s pay cycle).
This definition does not indicate that drinking more than 4 standard drinks in a single day less often than once a month is safe—the guideline indicates that exceeding 4 standard drinks on any one day results in an increased risk of alcohol-related injury or disease. The less a person drinks, the lower their risk of harm from alcohol. This definition is designed to estimate the proportion of people who consistently exceeded the recommended alcohol consumption guideline over the previous 12 months.
Final measurement definition for guideline 1
Any person who, in the past 12 months:
- Consumed no more than 10 standard drinks per week on average; and
- Never consumed more than 4 standard drinks on a single day (or did so less often than once per month on average)
will be classified as having consumed alcohol in ways that reduced their risk of experiencing alcohol-related disease or injury (i.e. reduced the lifetime risk of dying from alcohol-related disease or injury to below 1 in 100 for healthy men and women).
In contrast, people who reported drinking more than 10 standard drinks per week or who drank more than 4 standard drinks on a single day at least once a month on average will be classified as having consumed alcohol in ways that increased their risk of harm.
Guideline 1 applies to healthy men and women aged 18 years and over. Results below are for adults aged 18 and over. The online data tables also include results for the entire NDSHS sample, as a measure of alcohol consumption rather than drinking behaviour relative to guideline advice.