Separate and Joint Effects of Alcohol and Smoking on the Risks of Cirrhosis and Gallbladder Disease in Middle-aged Women

The separate and joint effects of alcohol and smoking on incidencesof liver cirrhosis and gallbladder disease were examined ina prospective study of 1,290,413 United Kingdom women (meanage, 56 years) recruited during 1996–2001. After a meanfollow-up of 6.1 years (1996–2005), incidence rates ofcirrhosis and gallbladder disease were 1.3 per 1,000 persons(n = 2,105) and 15 per 1,000 persons (n = 23,989), respectively,over 5 years. Cirrhosis risk increased with increasing alcoholconsumption, while the risk of gallbladder disease decreased(P_trend < 0.0001 for each). Comparing women who drank 15units/week with those who drank 1–2 units/week, the relativerisk was 4.32 (95% confidence interval (CI): 3.71, 5.03)) forcirrhosis and 0.59 (95% CI: 0.55, 0.64) for gallbladder disease.Increasing numbers of cigarettes smoked daily increased therisk of both conditions (P_trend < 0.0001 for each). Comparingcurrent smokers of 20 cigarettes/day with never smokers, therelative risk was 3.76 (95% CI: 3.25, 4.34) for cirrhosis and1.29 (95% CI: 1.22, 1.37) for gallbladder disease. Effects ofalcohol and smoking were more than multiplicative for cirrhosis(P_interaction = 0.02) but not for gallbladder disease (P_interaction= 0.4). Findings indicate that alcohol and smoking affect therisks of the 2 conditions in different ways. For cirrhosis,alcohol and smoking separately increase risk, and their jointeffects are particularly hazardous. For gallbladder disease,alcohol reduces risk and smoking results in a small risk increase. alcohol drinking; gallbladder diseases; liver cirrhosis; liver diseases, alcoholic; prospective studies; smoking