The relationship between alcohol use and risk of death has been studied widely, and often a J-shaped risk curve is found, where low-level drinkers appear to have decreased risk compared to non-drinkers, and heavy drinkers the highest risk. But many of these studies have not accounted for a critical issue called the ‘sick-quitter effect’. In our new study, we summarised the evidence on alcohol and risk of death in evidence reviews that have been conducted globally, with a focus on the methods that were used.
What is the ‘sick-quitter effect’?
The sick-quitter effect relates to people who have stopped drinking alcohol due to ill-health. These people often appear in health data as non-drinkers but may have already incurred harms from alcohol which led them to quit drinking.
When a study uses non-drinkers as the comparison group (many of whom are ex-drinkers with health problems), it can falsely make the harms of drinking appear smaller or non-existent, or even make it seem like drinking small quantities of alcohol protects against harms. This is the sick-quitter effect.
What did we do?
We reviewed the evidence from systematic reviews of the relationship between alcohol and risk of death that have been published globally. We searched five medical literature databases and identified 25 reviews published since 1993.
We divided these reviews into those that used a comparison group of non-drinkers, and may therefore have been affected by the sick-quitter effect, and those that used other comparison groups (such as lifetime abstainers or occasional drinkers). We also assessed the methodological quality and risk of bias in all reviews using an appraisal tool called ROBIS (Risk of Bias in Systematic Reviews).
What did we find?
Over 70% of the global reviews examining the risk of death associated with alcohol published over the past 30 years did not exclude former drinkers from the comparison group, and may therefore be biased by the sick-quitter effect.
Of the five reviews that were not affected by the sick-quitter issue, three reviews reported a J-shaped relationship between alcohol risk of death, while two reviews did not. These two reviews reported an increased risk of death in relation to increasing levels of alcohol use. All five reviews reported increased risk with high levels of alcohol use.
Only one review was considered a high-quality review at low risk of bias. This review examined 22 individual studies without former drinkers in the comparison group, and found that the risk of death increases with increasing alcohol use, with no evidence of any protective effects for low-level drinking.
In contrast, 17 of the 20 remaining reviews reported decreased risk of death for low-level drinking.
What does this all mean?
Firstly, our findings suggest that review studies over the past 30 years may have underestimated the number of deaths caused by alcohol. This has implications for studies that model the harms of alcohol, government guidelines on alcohol use, alcohol-related clinical practice guidelines, and government policies aiming to address alcohol-related harms. Our review only investigated studies that examined alcohol and risk of death, but the sick-quitter effect is likely to affect studies of other outcomes too, including cardiovascular disease, cancer, and liver disease.
Secondly, our review strengthens the weight of the evidence surrounding the harms of alcohol use. Governments should respond to this evidence and invest in campaigns to raise awareness of the long-term health risks associated with alcohol use, including cancer risk, and implement policies to address the pricing, availability, and advertising of alcohol, that have been shown to help reduce alcohol harms in the community. Some policy examples include limiting the density of alcohol retailers, limiting young people’s exposure to alcohol advertising, limiting alcohol advertising during sporting events, and reforms to alcohol pricing such as volumetric taxation or minimum unit pricing.
This study is also a timely reminder for people to follow national health guidelines on alcohol. While there is no safe amount of alcohol, the less you drink, the lower your risk of harm from alcohol – especially cancer.
Please click here if you would like to read more about our study.
Written by Dr Peter Sarich, Research Fellow at The Daffodil Centre, The University of Sydney, A Joint Venture with Cancer Council NSW, Australia.
All IAS Blogposts are published with the permission of the author. The views expressed are solely the author’s own and do not necessarily represent the views of the Institute of Alcohol Studies.
References:
1. Sarich, P., Gao, S., Zhu, Y., Canfell, K., & Weber, M.F. (2024). The association between alcohol consumption and all-cause mortality: An umbrella review of systematic reviews using lifetime abstainers or low-volume drinkers as a reference group. Addiction.
2. Whiting, P., Savović, J., Higgins, J.P., Caldwell, D.M., Reeves, B.C., Shea, B., Davies, P., Kleijnen, J., Churchill, R.; ROBIS group. (2016). ROBIS: A new tool to assess risk of bias in systematic reviews was developed. Journal of Clinical Epidemiology. 69:225-234.
3. Stockwell, T., Zhao, J., Panwar, S., Roemer, A., Naimi, T., & Chikritzh, T. (2016). Do “Moderate” Drinkers Have Reduced Mortality Risk? A Systematic Review and Meta-Analysis of Alcohol Consumption and All-Cause Mortality. Journal of Studies on Alcohol and Drugs, 77(2), 185-198.
4. Cancer Council Australia. (2024). Limit Alcohol. Cancer Council Australia. https://www.cancer.org.au/cancer-information/causes-and-prevention/diet-and-exercise/limit-alcohol.
5. National Health and Medical Research Council (NHMRC). (2024). Australian guidelines to reduce health risks from drinking alcohol. NHMRC. https://www.nhmrc.gov.au/health-advice/alcohol
6. The Daffodil Centre. (2024). The Sick-Quitter Effect: Alcohol-related death has been underestimated over the past 30 years. The Daffodil Centre. https://daffodilcentre.org/the-sick-quitter-effect-alcohol-related-death-has-been-underestimated-over-the-past-30-years/