Even Modest Alcohol Intake May Up Mortality Risk

Norra MacReady

April 13, 2018

A new analysis of data on nearly 600,000 people suggests that the association between alcohol use and risk for all-cause mortality begins at consumption levels much lower than previously thought.

Mortality risk was lowest for people who drank 100 g of alcohol per week or less and showed a positive and curvilinear relationship with higher alcohol doses, Angela M. Wood, PhD, and colleagues write in an article published in the April 14 issue of the Lancet. In the United Kingdom, 100 g of alcohol is equivalent to 5 to 6 standard glasses of wine or pints of beer.

Similarly, the authors observed a roughly curvilinear relationship between alcohol consumption and cardiovascular disease except for myocardial infarction, which showed an inverse relationship with the amount consumed.

All in all, the findings "support adoption of lower limits of alcohol consumption than are recommended in most current guidelines," Wood, from the Department of Public Health and Primary Care at the University of Cambridge in the United Kingdom, and colleagues write. For example, in the United States, the maximum recommended weekly intake for men is 196 g, whereas "Italy, Portugal, and Spain recommend low-risk limits almost 50% higher."

The key message of this research for the public is that "if you already drink alcohol, drinking less may help you live longer and lower your risk of several cardiovascular conditions," Wood said in a journal news release.

The findings come as recent data from the Centers for Disease Control and Prevention suggest that as many as 37 million people in the United States, or roughly 1 in 6 adults, may engage in regular binge drinking. Excessive alcohol consumption is held responsible for 88,000 deaths in the United States annually.

The authors of this study were motivated to conduct their research by the disparity in international alcohol consumption guidelines, reasoning that such variation "might reflect ambiguity about drinking risk thresholds associated with the lowest risk of mortality, as well as uncertainty about the specific consequences of alcohol consumption, including those related to cardiovascular disease subtypes," they write.

The analysis included individual-participant data from 83 prospective, long-term studies conducted in 19 high-income countries, with the goal of identifying risk thresholds for all-cause mortality and cardiovascular disease associated with alcohol consumption. Eligible participants had to be current drinkers with no history of cardiovascular disease at baseline.

A total of 599,912 participants met these criteria. They had a mean age of 57 years and were recruited into their respective studies between 1964 and 2010. About 50% of the study participants consumed more than 100 g of alcohol per week, with 8.4% reporting consumption in excess of 350 g per week.

The participants were followed for a median of 7.5 years, or a total of 5.4 million person-years. During this time, there were 40,310 deaths from all causes, including 11,762 deaths from cardiovascular illnesses and 15,150 deaths related to cancer. Another 39,018 participants experienced a first-incident cardiovascular outcome, including 12,090 stroke, 14,539 myocardial infarction, 7990 coronary artery disease (excluding myocardial infarction), 2711 heart failure events, and 1121 deaths from other cardiovascular disorders.

For all-cause mortality, "there was a positive and curvilinear association with alcohol consumption, with the lowest risk for those consuming below 100 g per week," the authors write.

The relationship with cardiovascular disease was somewhat less straightforward. After adjustment for age, sex, smoking, and history of diabetes, the amount of alcohol consumed showed roughly linear associations with stroke (hazard ratio [HR] per 100 g/week higher consumption, 1.14; 95% confidence interval [CI], 1,10 - 1,17), coronary disease excluding myocardial infarction (HR, 1.06; 95% CI,1.00 - 1.11), heart failure (HR, 1.09; 95% CI, 1.03 - 1.15), fatal hypertensive disease (HR, 1.24; 95% CI, 1.15 - 1.33), and fatal aortic aneurysm (HR 1.15; 95% CI, 1.03 - 1.28).

For myocardial infarction, however, there was an inverse and approximately log linear association with alcohol use (HR, 0.94; 95% CI, 0.91 - 0.97). Adjustment for systolic blood pressure strengthened this inverse association further, whereas adjustment for high-density lipoprotein cholesterol weakened it.

The analysis also confirmed the association between alcohol consumption and cancers of the digestive tract. In November 2017, the American Society of Clinical Oncology issued a formal statement urging clinicians to warn patients that alcohol is a risk factor for many types of malignancies and to encourage them to reduce their cancer risk by drinking less.

With respect to alcohol's effect on survival, the authors found that compared with "those who reported drinking >0-≤100 (mean usual 56 g) alcohol per week, those who reported drinking >100-≤200 g (mean usual 123 g) per week, >200-≤350 g (mean usual 208 g) per week or >350 g (mean usual 367 g) per week had shorter life expectancy at age 40 years of approximately 6 months, 1–2 years, or 4–5 years respectively."

Overall, men who kept their weekly alcohol intake below 100 g had a life expectancy at age 40 years about 1 to 2 years longer than men who drank 196 g per week. For women who consumed more than the UK weekly limit of 112 g or the US threshold for women of 98 g, life expectancy at age 40 years was 1.3 years shorter than that of women who drank less.

This analysis "substantially improves on previous meta-analyses to define low-risk drinking thresholds," Jason Connor, PhD, writes in an accompanying editorial.

However, not everyone will welcome these findings, warns Connor, from the University of Queensland Centre for Youth Substance Abuse Research, The University of Queensland, St Lucia, Australia. "The drinking levels recommended in this study will no doubt be described as implausible and impracticable by the alcohol industry and other opponents of public health warnings on alcohol."

Nevertheless, he concludes, "the findings ought to be widely disseminated and they should provoke informed public and professional debate."

The study authors reported receiving grants and other forms of financial support from Merck, Biogen, Novartis, Bioverativ, Pfizer, Zoll LifeCor, Johnson & Johnson, Janssen, United Health, IBM Watson, Element Science, Aetna, Hugo, Medtronic, Merck Sharp & Dohme UK, the Wellcome Trust, AstraZeneca, Nestle, Metagenics, The Medicines Company, GSK, DalCor, Sanofi, Berlin-Chemie, Kowa, Amgen, Roche Diagnostics, Beckmann, Singulex, and Abbott. Connor has disclosed no relevant financial relationships.

Lancet. 2018;391:1460-1461, 1513-1523. Full text

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