MedicalResearch.com Interview with:
Dr. Jinhui Zhao PhD
Scientist, Centre for Addictions Research of BC
University of Victoria
MedicalResearch.com: What is the background for this study? What are the main findings?
Response: There are now many studies questioning the validity of the theory that moderate alcohol consumption protects against heart disease. We provided an up to date and comprehensive review of the evidence from ‘cohort’ studies i.e. those that assess health risk behaviours of people then follow them up for a number of years to see what characteristics predict death from a particular condition. We wished to test the theory that the appearance of health benefits in relation to heart disease is due to biases that accumulate and become more severe when cohorts are recruited at older ages (e.g. over 55 years). We found evidence to support this hypothesis. Moderate drinkers recruited before 55 years of age did not show any evidence of reduced risk of heart disease even when followed up into old age. Moderate drinkers from the older cohorts, however, did appear to have significant benefits – a finding we attribute to selection biases that accumulate across the life-course.
Several published meta-analyses showed inconsistent findings about how alcohol consumption affects the risk of coronary heart disease (CHD). Most systematic reviews find associations between low-volume alcohol consumption and reduced CHD risk, while some also find increased CHD risk for higher levels of consumption (Maclure 1993, Corrao, Rubbiati et al. 2000, Corrao, Bagnardi et al. 2004, Ronksley, Brien et al. 2011, Roerecke and Rehm 2012). More recent evidence has accumulated to suggest that the case for cardio-protection may be less straightforward. The association of alcohol consumption with CHD may be confounded or modified by other factors such as age and sex and / or biased by those factors which have not been investigated or controlled for in these previously published studies.