You Cant Handle the Truth! Comparing Serum Phosphatidylethanol to Self-Reported Alcohol Intake

Introduction: Serum phosphatidylethanol (PEth) testing has emerged as a promising biomarker for assessing recent alcohol consumption, offering an objective measure of alcohol intake. With self-reporting limited by recall bias and underreporting, objective measures have become increasingly relied upon for assessing clinical compliance. Although studied within clinical trials, limited data exists comparing PEth levels and patients' reported alcohol intake in the general population. This study aims to compare PEth testing results with self-reported alcohol intake and assess variables associated with underreporting. Methods: Single-center retrospective cohort study of all patients with a serum PEth test from 2/1/2019 - 9/30/2022. Only a patient's first positive PEth (10 ng/mL or greater) was used in the analysis. PEth results were categorized as mild (10-20), moderate (20-200), or heavy ( >200) using pre-established laboratory cutoffs. Self-reported alcohol consumption was recorded within 6 weeks of a positive PEth result as no/mild drinking (0-1 standard drinks per week (SDW)), moderate (2-14 SDW), and heavy ( >14 SDW) using established definitions. Severity measures between self-report and PEth were assessed using Bhapkar's test and Bonferroni-adjusted McNemar's tests. Demographic data was analyzed for associations with underreporting using Chi-Square tests. Results: Of the 869 unique patients, 297 had both a positive PEth and self-reported drinks in the study period. 94 (33.7%) patients had concordance with self-report, and 203 (66.3%) patients had discordance, P < 0.0001. 55 (19.7%) patients self-reported light consumption but had heavy PEth level. Heavy and moderate PEth patients were more likely to report light severity than light PEth to report heavy or moderate intake, P < 0.001. 58% and 56.4% of alcohol-related and non-alcohol-related cirrhotic patients underreported alcohol use, respectively. Conclusion: In this retrospective analysis, we have shown that patients significantly differ between their self-reported alcohol intake and PEth testing, particularly in patients with heavy and moderate PEth categorization. This reinforces the clinical importance of PEth testing as an objective clinical measure. In addition to further investigation into this relationship and its confounding factors, areas of further interest include exploration of alcohol consumption underreporting in non-alcohol related cirrhosis and underreporting in predicting abstinence in cirrhotic patients (Table 1). Table 1. - Self Reported Drinks Compared to PEth Severity Self reported drinks PEth severity Frequency (percent) Light Moderate Heavy Total Light 21 (7.53%) 78 (27.96%) 55 (19.71%) 154 (55.20) Moderate 5 (1.79%) 29 (10.39%) 28 (10.04%) 62 (22.22%) Heavy 1 (0.36%) 18 (6.45%) 44 (15.77%) 63 (22.58%) Total 27 (9.68%) 125 (44.80%) 127 (45.52%) 279 (100%)