Abstract
OBJECTIVES: To systematically summarize the risk relationship between different levels of alcohol consumption and incidence of liver cirrhosis. METHODS: MEDLINE and Embase were searched up to March 6, 2019, to identify case-control and cohort studies with sex-specific results and more than 2 categories of drinking in relation to the incidence of liver cirrhosis. Study characteristics were extracted and random-effects meta-analyses and meta-regressions were conducted. RESULTS: A total of 7 cohort studies and 2 case-control studies met the inclusion criteria, providing data from 2,629,272 participants with 5,505 cases of liver cirrhosis. There was no increased risk for occasional drinkers. Consumption of one drink per day in comparison to long-term abstainers showed an increased risk for liver cirrhosis in women, but not in men. The risk for women was consistently higher compared to men. Drinking ≥5 drinks per day was associated with a substantially increased risk in both women (relative risk [RR] = 12.44, 95% confidence interval [CI]: 6.65-23.27 for 5-6 drinks, and RR = 24.58, 95% CI: 14.77-40.90 for ≥7 drinks) and men (RR = 3.80, 95% CI: 0.85-17.02, and RR = 6.93, 95% CI: 1.07-44.99, respectively). Heterogeneity across studies indicated an additional impact of other risk factors. DISCUSSION: Alcohol is a major risk factor for liver cirrhosis with risk increasing exponentially. Women may be at higher risk compared to men even with little alcohol consumption. More high-quality research is necessary to elucidate the role of other risk factors, such as genetic vulnerability, body weight, metabolic risk factors, and drinking patterns over the life course. High alcohol consumption should be avoided, and people drinking at high levels should receive interventions to reduce their intake.