Phosphatidylethanol testing: patterns, demographic and clinical correlates, and outcomes

Phosphatidylethanol (PEth) is a widely used biomarker for alcohol use, but interpretation may vary by demographic factors, and the clinical relevance of current cutoffs is uncertain. We examined the distribution of PEth values across a large healthcare network and the associations between PEth and demographics, lab markers, and clinical outcomes.

We conducted a retrospective cohort study of 4892 adults with ≥1 PEth 16:0/18:1 result from January 2022 to August 2024 within the Mass General Brigham system. Linear regression assessed associations between PEth and demographic characteristics, aspartate aminotransferase (AST), low-density lipoprotein, A1c, hospital encounters, length of stay, and self-reported alcohol use.

60% of patients had negative PEth (<20 ng/mL). Among positives, the median was 251 ng/mL. 18% had moderate (20-200 ng/mL) and 22% heavy (>200 ng/mL) alcohol use. PEth was directly associated with AST (P < .001) and inversely with age (P < .001), body mass index (P = .019), income (P = .010), and A1c (P = .0044). Black patients had higher PEth than White patients (P < .001). No differences by gender were observed. Higher PEth was associated with more hospital encounters (P < .001) but shorter stays (P < .001). PEth did not correlate well with self-reported alcohol intake, and 31% of patients with positive PEth reported no alcohol use.

In a broad clinical population, PEth values were higher than previously reported. Demographic disparities and limited agreement with self-report suggest PEth may better detect unhealthy alcohol use and reveal unmet care needs.