The cardioprotective association of average alcohol consumption and ischaemic heart disease: a systematic review and meta-analysis

Aims Most, but not all, epidemiological studies suggest a cardioprotective association for low to moderate average alcohol consumption. The objective was to quantify the dose–response relationship between average alcohol consumption and ischaemic heart disease (IHD) stratified by sex and IHD end‐point (mortality versus morbidity). Methods A systematic search of published studies using electronic databases (1980–2010) identified 44 observational studies (case–control or cohort) reporting a relative risk measure for average alcohol intake in relation to IHD risk. Generalized least‐squares trend models were used to derive the best‐fitting dose–response curves in stratified continuous meta‐analyses. Categorical meta‐analyses were used to verify uncertainty for low to moderate levels of consumption in comparison to long‐term abstainers. Results The analyses used 38 627 IHD events (mortality or morbidity) among 957 684 participants. Differential risk curves were found by sex and end‐point. Although some form of a cardioprotective association was confirmed in all strata, substantial heterogeneity across studies remained unexplained and confidence intervals were relatively wide, in particular for average consumption of one to two drinks/day. Conclusions A cardioprotective association between alcohol use and ischaemic heart disease cannot be assumed for all drinkers, even at low levels of intake. More evidence on the overall benefit–risk ratio of average alcohol consumption in relation to ischaemic heart disease and other diseases is needed in order to inform the general public or physicians about safe or low‐risk drinking levels.