Thirty Years of Observational Studies of Alcohol’s Cardioprotective Effects: Uncertainty Remains

This meta-analysis combined 44 observational studies from 1980–2010 that reported a relative risk for ischemic heart disease (IHD) in relation to average alcohol intake.

• The well-known J-shaped curve was confirmed (i.e., compared with abstainers, IHD risk is lower in people with low-level alcohol consumption but rises with increasing consumption).

• The maximum cardioprotective effects for mortality occurred between 32–63 g alcohol* per day for men and between 11–31 g per day for women.

• The effects were heterogeneous, even at low levels of intake.

Comments:

Although this study reaffirms the population-level association between low-level alcohol intake and reduced cardiovascular morbidity and mortality, the high level of heterogeneity means it is very difficult for clinicians to make inferences about individual patients. Some people benefit from low-level drinking while others are harmed, and we cannot differentiate these groups. Furthermore, meta-analysis of even a large number of studies does not eliminate the possibility that residual confounding could explain the findings (e.g., IHD was reduced because of better risk-factor profiles among those who draink low-level amounts). Although advising patients about lower risk drinking limits is the current standard of practice, considerable uncertainty remains about what constitutes a safe level of consumption, and for whom.

Peter D. Friedmann, MD, MPH

Reference:

Roerecke M, Rehm J. The cardioprotective association of average alcohol consumption and ischaemic heart disease: a systematic review and meta-analysis. Addiction. January 9, 2012 [Epub ahead of print]. doi: 10.1111/j.1360- 0443.2012.03780.x.