Alcohol and liver injury: dose-related or permissive effect?

Studies addressing the risk of development of cirrhosis of the liver in relation to alcohol consumption have been based on comparisons at the aggregate population level and, at the individual level, on case-control studies and cohort studies, and on retrospective and prospective assessment of alcohol consumption. The ideal, but unfeasible, study design for estimation of the risk function is a prospective monitoring of alcohol consumption and recording of the rate of development of cirrhosis per unit of time. Two recent studies, approaching this design, suggested that above a rather low, but not precisely determined, level of alcohol consumption the risk of development of cirrhosis is not further influenced by the amount of alcohol consumed. A critical analysis of previous studies suggests that this risk function is actually compatible with their findings. The contention that alcohol abuse has a permissive rather than a dose-dependent role in the development of alcoholic liver injury encourages research into the additional factors that must act before the liver injury occurs.