Blood concentrations of PEth are highly correlated to ethanol intake, and the present results indicate that its diagnostic sensitivity is higher than that for previously established alcohol markers.

PEth was the biomarker with the best correlation to self-reported alcohol consumption. PEth was superior to CDT owing to its substantially higher sensitivity but also due to its closer correlation to self-report. PEth values can be translated into an approximate level of alcohol consumption and PEth appears to be a more reliable measure of alcohol consumption than self-reports.

Although the results of the main outcome of this study did not support an effect of varenicline in alcohol-dependent individuals, the secondary analyses of PEth, craving and AUDIT score support an effect of varenicline on alcohol consumption. The disclosure of a treatment effect and the lack of a clear placebo effect when using PEth as outcome variable, together with a nonsymmetric bias associated with self-reported data, strongly argue for using the specific biomarker PEth in studies of treatments of alcohol dependence.