THE LIFE AND TIMES OF THE J-SHAPED CURVE

( Received 18 August 2006; first review notified 25 August 2005; in revised form 28 August 2006; accepted 28 August 2006)Epidemiologists continue to conduct prospective studies of the association between alcohol consumption and mortality; both all-cause mortality and one of its biggest drivers, deaths from coronary disease. Our fascination centres on the health-enhancing effects of light to moderate frequent drinking. This is the halcyon zone where alcohol is anxiolytic and relaxing, improves our meal, enhances our social life, and prevents our coronary disease without appearing to inflict much damage. Some have suggested we are fooling ourselves. Couldn't these J-shaped curves result from biases common to all of the studies?While there is an impressive consistency about the shape of the relationships between alcohol and mortality in many studies, with closer scrutiny there is an interesting heterogeneity in the levels and patterns of drinking that are associated with risk and benefit. Several methodological issues affect prospective non-randomized studies of alcohol consumption and mortality that contribute to this variation, and threaten the validity of these studies.The first is that alcohol consumption is very strongly socially determined and so it is likely that there is substantial residual confounding of its association with mortality by factors other than those measured and adjusted for. That is to say, moderate frequent drinkers have other reasons to die less often than non-drinkers, and heavy drinking is a marker of a short life as well as a cause.Second, drinking pattern is important for at least the two biggest determinants of alcohol-related mortality, coronary …