tl;dr: People drinking no alcohol tend to have a higher mortality rate than moderate drinkers because the majority of them have a history of alcohol or drug abuse.

> Of the abstainers, 322 (72.04%) had met one or more criteria for former alcohol or drug dependence or abuse, alcohol risky drinking, or had tried to cut down or to stop drinking, were daily smokers, or self-rated their health as fair to poor.