Alcohol consumption over time and risk of death: a systematic review and meta-analysis

The results from the few cohort studies that have measured usual alcohol consumption over time have not been summarized. We therefore conducted a systematic review and meta-analysis to quantify mortality risk. Pertinent studies were identified by searching the Medline, Web of Science, Cumulative Index to Nursing and Allied Health Literature (CINAHL) Plus, and Scopus databases through August 2012 using broad search criteria. Studies reporting relative mortality risks for quantitatively defined categories of alcohol consumption over time were eligible. Nine cohort studies published during 1991-2010 (comprising 62,950 participants and 10,490 deaths) met the inclusion criteria. For men, there was weak evidence of lower mortality risk with low levels of alcohol intake over time but higher mortality risk for those with intakes over 40 g/day compared with abstainers using a random-effects model (P for nonlinearity = 0.02). The pooled relative risks were 0.90 (95% confidence interval: 0.81, 0.99) for 1-29 g/day, 1.19 (95% confidence interval: 0.89, 1.58) for 30-59 g/day, and 1.52 (95% confidence interval: 0.78, 2.98) for 60 or more g/day compared with abstention. There was moderate between-study heterogeneity but no evidence of publication bias. Studies including women were extremely scarce. Our findings include a curvilinear association between drinking over time and mortality risk for men overall and widespread disparity in methods used to capture exposure and report results.