Background: To compare the strength of evidence provided by the epidemiological literature on the association between alcohol consumption and the risk of 14 major alcohol-related neoplasms and non-neoplastic diseases, plus injuries.
Methods: A search of the epidemiological literature from 1966 to 1998 was performed by several bibliographic databases. Meta-regression models were fitted considering fixed and random effect models and linear and nonlinear effects of alcohol intake. The effects of some characteristics of the studies, including an index of their quality, were considered.
Results: Of the 561 initially reviewed studies, 156 were selected for meta-analysis because of their a priori defined higher quality, including a total of 116,702 subjects. Strong trends in risk were observed for cancers of the oral cavity, esophagus and larynx, hypertension, liver cirrhosis, chronic pancreatitis, and injuries and violence. Less strong direct relations were observed for cancers of the colon, rectum, liver, and breast. For all these conditions, significant increased risks were also found for ethanol intake of 25 g per day. Threshold values were observed for ischemic and hemorrhagic strokes. For coronary heart disease, a J-shaped relation was observed with a minimum relative risk of 0.80 at 20 g/day, a significant protective effect up to 72 g/day, and a significant increased risk at 89 g/day. No clear relation was observed for gastroduodenal ulcer.
Conclusions: This meta-analysis shows no evidence of a threshold effect for both neoplasms and several non-neoplastic diseases. J-shaped relations were observed only for coronary heart disease.