The effects of modest drinking on life expectancy and mortality risks: a population-based cohort study

Modest drinking has been repeatedly discussed in scientific papers as protective against certain diseases, such as cardiovascular diseases, but in most cases, alcohol worsens health conditions, especially when consumed at high risk levels. The complexity of the risk relationship between alcohol and health conditions has confused clinicians as to whether it should be recommended. The study aims to balance the risks and benefits of modest drinking. This retrospective cohort study of 430,016 adults recruited from a standard health-screening program since 1994, with 11,031 deaths identified as of 2008. Drinking distinguished "modest drinker" (no more than one drink a day) from "regular drinker". Mortality risks including all-cause mortality and diseases-specific mortality with hazard ratio (HR) were calculated by adjusting for 15 confounders. Life table was used for life expectancy. Risk predictors were subjected to Cox proportional hazards regression analysis to identify significant predictors in multivariate models and life expectancy analysis. Nearly one out of 4 males (23%) was a modest drinker, who gained 0.94 year (95% CI 0.65-1.23 year) in life over non-drinker and had 8% reduction in adjusted all-cause mortality (HR 0.92, 95% CI 0.86-0.97). In contrast, regular drinkers had 43% increase in overall mortality (HR 1.43, CI 1.35-1.52) and shortened life by 6.9 years (95% CI 6.6-7.1 years). As most drinkers also smoked, 59% in modest and 75% in regular, the combined effect shortened life by 2.0 years (95% CI 1.6-2.4 years) in modest drinker and 10.3 years (95% CI 9.8-10.7 years) in regular drinker. Cancer were increased in modest drinkers for oral (HR 2.35, CI 1.38-4.01) and esophageal (HR 3.83, CI 1.90-7.73) cancer. The gain of one year by modest drinkers was erased by a two to fourfold increase in oral and esophageal cancer and that drinking beyond modest amount led to a large loss of life expectancy. Given that drinkers are prone to cross the line of drinking, clinicians should balance the risks and benefits of drinking, as well as the understanding of whether the patient is at risk for addiction.