THE EFFECT OF DRINKING COFFEE AND SMOKING CIGARETTES ON THE RISK OF CIRRHOSIS ASSOCIATED WITH ALCOHOL-CONSUMPTION - A CASE-CONTROL STUDY

In order to assess the interaction between alcohol intake, tobacco smo king and coffee consumption in determining the risk of liver cirrhosis we carried out a hospital-based case-control study involving 115 pati ents at their first diagnosis of cirrhosis and 167 control patients co nsecutively enrolled in the General Hospitals of the Province of L'Aqu ila (Central Italy), The mean life-time daily alcohol intake (as g eth anol consumed daily) was measured by direct patient interviews, whose reproducibility was > 0.80 and similar for cases and controls, as chec ked by interviewing the relatives of a sample of 50 cases and 73 contr ols. During the same patient's interview we also measured the mean con sumption of coffee (daily number of cups of filtered coffee) and tobac co (life-time daily number of cigarettes smoked). A dose-effect relati onship on the risk of cirrhosis was present both for alcohol intake - for which the risk was significantly increased above 100 g of daily in take - and for cigarette consumption, The latter did not however impro ve the goodness-of-fit of a logistic regression model including alcoho l intake as covariate. By contrast, coffee consumption had a protectiv e effect on the risk of cirrhosis and significantly improved the goodn ess-of-fit of such a model, Abstaining from coffee consumption determi ned both a significantly increased risk of cirrhosis, even for daily a lcohol intake below 100 g, and a multiplicative effect with alcohol in take on this risk. In patients drinking greater than or equal to 101 g ethanol daily the relative risk increased from 5.5 (95% confidence in terval: 1.4-22.0) for coffee consumers to 10.8 (95% confidence interva l: 1.3-58.1) for coffee abstainers. We conclude that: (1) tobacco smok ing is likely to be a faint risk factor for cirrhosis, and studies on wider patients series should be performed for confirmation; (2) coffee drinking is associated with a reduced risk of cirrhosis. Whether coff ee contains some hitherto unknown protective substances, or is just a marker of other life-style or dietary protective factors, deserves fur ther clarification.