Decline of phosphatidylethanol (B‐PEth) during abstinence in patients with alcohol use disorder undergoing withdrawal treatment, and the correlation of B‐PEth with self‐reported alcohol intake

BACKGROUND AND AIM: Accurately estimating alcohol consumption is crucial for clinical decision-making and monitoring treatment outcomes. Phosphatidylethanol in blood (B-PEth), a direct alcohol biomarker, is currently the most reliable indicator of alcohol intake, with a detection window of several weeks; however, the factors influencing the decline of B-PEth levels remain largely unknown. This study aimed to investigate the decline of B-PEth levels during abstinence in patients with alcohol use disorder (AUD) undergoing withdrawal treatment. METHOD: A total of 100 patients were recruited in withdrawal treatment and followed during three to four weeks of abstinence. Blood samples were collected at baseline and weekly during abstinence to measure B-PEth levels of two homologues (16:0/18:1 and 16:0/18:2). Self-reported alcohol consumption was documented using the Timeline Followback (TLFB) method for 30 days before abstinence and throughout the study period. RESULTS: B-PEth elimination followed first-order kinetics. The mean half-life was 7.24 days [95% confidence interval (CI) = 6.98-7.53] for 16:0/18:1 and 4.55 days (95% CI = 4.44-4.67) for 16:0/18:2. The rate of decline varied by week, with a longer half-life observed in week three compared with week one. No statistically significant sex differences were detected. The strongest correlation between B-PEth levels and self-reported alcohol consumption was found for data from two weeks prior to abstinence. CONCLUSION: Elimination of phosphatidylethanol in blood (B-Peth) follows first-order kinetics, with homologue 16:0/18:1 exhibiting a longer half-life than 16:0/18:2. The rate of decline is influenced by the week of alcohol abstinence and B-PEth levels are detectable even in the fourth week of abstinence. The strongest correlation between B-PEth and self-reported alcohol consumption is at two weeks prior to abstinence.