Context matters: Canada’s guidance on alcohol and health needs a rethink

Canadians know by now that our new Guidance on Alcohol and Health encourages us to consume no more than two standard drinks per week, claiming that three to six drinks per week constitutes a moderate risk and seven or more confers a high risk of premature death due to alcohol consumption. However, the public summary, which is all that most people see, does not define low, moderate or high risk, nor does it distinguish between seven drinks in one sitting vs. a glass of wine with dinner seven days a week.

As a moderate consumer of wine with dinner, I have examined the full technical report to determine my true risk. Using the report’s own data, I conclude that my risk is considerably lower than the high risk conveyed in the public summary – perhaps by a factor of five.

Risk of death

The report focused on 16 published systematic reviews, two on the short-term risk of death from injury and 14 on the long-term risk of premature death from alcohol-related diseases. The report accepted that for voluntary human activities that carry a risk of death, society considers a death risk of one in 1,000 to be low, and 10 times this, or one in 100, to be the threshold for high risk. To determine the risk at each level of alcohol consumption, the report determined the age of death and life expectancy of each study participant who died, and then calculated the number of years of life lost per 1,000 study participants, abbreviated as YLL/1000. Noting that the average number of years lost per death from disease or injury is 17.5 years, they considered a loss of life totalling 17.5 YLL/1000 as equivalent to 1/1,000 deaths and set this as the upper end of low risk. Loss of life totalling 10 times this (175 YLL/1000) was set as the threshold for high risk.

The report tabulates YLL/1000 for several diseases at lifetime average consumption levels from one to 35 drinks per week. Here is the data for seven drinks per week:

Years of Life Lost per 1,000 individuals (YLL/1000) consuming 7 standard drinks per week

This table summarizes the data from Tables 3 and 4 of the full technical report. Those tables present the data on YLL/1000 for these 21 different alcohol-influenced diseases and injuries for 10 different levels of alcohol consumption ranging from one to 35 standard drinks per week. This analysis is focused on a level of seven drinks per week because it is the level immediately above the stated high-risk threshold; is a level that may be applicable to many moderate consumers; and pertains directly to my own risk calculation. I organized the data as non-cancer diseases, cancer and injury to aid discussion of the results. For the full data, set see pages 27 and 28 of the technical report at https://www.ccsa.ca/sites/default/files/2023-01/Canada%27s%20Guidance%20on%20Alcohol%20and%20Health%20Final%20Report.pdf

The sum of YLL/1000 for all diseases and injuries is 222 for males and 220 for females. This is 25 per cent above the high-risk threshold of 175 YLL/1000, confirming that seven drinks per week may be considered high risk. While not shown here, a similar analysis of data at 14 drinks per week yields a risk of four times the high-risk threshold, and at 21 drinks per week it is close to six times that threshold.

Calculating my own risk

The risk of death calculated from the table is a population average that does not consider consumption pattern or history. With a lifetime average of seven drinks per week, injuries account for 65 per cent of the total risk for males and 40 per cent for females; for males 60 per cent of that risk is for intentional injury, family violence for example. The report states, and common sense tells us, that virtually all injury risk may be attributed to heavy drinking leading to intoxication. However, that risk does not apply to this 80-year-old retired person who consumes a glass of wine with dinner most evenings.

Virtually all injury risk may be attributed to heavy drinking leading to intoxication.

Among the non-cancer diseases, the biggest contributor to premature death is cirrhosis of the liver, attributed mainly to heavy drinking over a long period of time. As someone who rarely consumes more than two drinks a day, this risk hardly applies to me. The remaining non-cancer diseases carry a relatively low risk, and for three of them the risk is negative (less than the risk for an abstainer). Consistent with earlier studies attributing a protective effect to the consumption of red wine, ischemic heart disease shows the most years saved at 64/1,000. The report argues that overall, the protective effects are not statistically significant, but 64 years of life saved though avoiding ischemic heart disease is double the 32 years of loss from cirrhosis, and those years saved is seen at one, two, three, four, five, six and seven drinks per week.

This leaves me with a risk of cancer – mainly cancer of the oral cavity, esophagus, and colon. That risk is largely balanced out by the protection from ischemic heart disease, a risk trade that I make willingly.

Calculating my wife’s risk

For women, the overall risk of premature death is similar with 220 YLL/1000, but the risk from injury is considerably less than for males, and the risk from cancer is greater with half of those deaths resulting from breast cancer. Women also have a reduction in premature death from Type 2 diabetes, and the data in the report exhibits this protection at all levels of consumption. I do not fully understand this, but recent data suggests that it is related to consumption of wine with meals. If this is the case, my wife would benefit from this protection in addition to the protection related to ischemic heart disease, largely compensating for her risk of death from cancer.

The bottom line

Taking all this into consideration, I calculate my actual risk in YLL/1000 to be 45 and for my wife 37. This gives us a risk of premature death of about 2.3 per 1,000, one fifth of the generic risk presented in the full technical report. And it should be noted that at our age, our risk of premature death from alcohol is small in comparison to all the other age-related risks we face.

One further point

Many people who attempt to estimate their own risk will use their current level of consumption as the starting point, and that would be wrong. The consumption data in the report is all based on lifetime average number of drinks per week, and that is what we used in our risk calculation. So, I can now confess that our current consumption is closer to two glasses of wine with dinner, but our estimated lifetime average is no more than seven standard drinks per week.

I acknowledge the extreme importance for Canadians to know and understand population health risks attributable to alcohol consumption. The report notes its own concern regarding the potential bias of information obtained through self-reported alcohol use. What my analysis shows is that guidance such as this must be accompanied by tools and data that allow individuals to estimate their own risk based on their age, current health, family history and consumption patterns over a lifetime.

Context really does matter, and a one-size-fits-all approach is unhelpful and for some, hurtful.