Abstract

Background:

Accurate alcohol assessments after liver transplants (LT) are crucial for understanding alcohol use and guiding treatment, particularly among LT recipients with prior alcohol-related liver disease (ALD). Biomarkers offer objective measures of alcohol exposure, but LT centers have not universally implemented routine biomarker use. Phosphatidylethanol (PEth) is a blood biomarker capable of detecting alcohol use during the prior 3-4 weeks. We assessed universal PEth testing for quantifying post-LT alcohol use in ALD and non-ALD LT recipients.

Methods:

We identified consecutive LT recipients with routine clinical PEth testing from a single LT center and compared three groups: standard LT (SLT; ≥6 months alcohol-free at LT), early LT (ELT; <6 months alcohol-free at LT), and non-ALD. The primary outcome was post-LT alcohol use, defined by positive PEth tests (i.e., >20 ng/mL). We used the Kruskal-Wallis test for between-group comparisons of continuous variables. Kaplan-Meier estimates analyzed times to the earliest positive PEth test, stratified by LT recipient group and compared by the log-rank test. We also created a multivariable Cox model to estimate hazard ratios for post-LT alcohol use, adjusting for age (using a five-knot restricted cubic spline), gender, and race/ethnicity. Our alpha was 0.05.

Results:

We included 159 LT recipients: 56 (35%) SLT, 42 (26%) ELT, and 61 (39%) non-ALD. Among the subjects, 64 (40%) were women, 123 (77%) identified as white, and the median age was 55 (IQR 45-62) years. The median follow-up time was 172 (IQR 69-288) days, and each LT recipient had a median of 8 (IQR 4-13) PEth tests. Overall, 26 (16%) LT recipients had at least one positive PEth test: 14 (25%) SLT, 9 (21%) ELT, and 3 (5%) non-ALD. Among those with positive PEth tests, the median time to the first positive test was 81 (IQR 57-120) days after hospital discharge from LT. Kaplan-Meier curves depicted significantly different times to the first positive PEth test between the groups (P=0.05) (Figure). Relative to SLT recipients, ELT recipients had similar risks of post-LT alcohol use (aHR 0.81; 95% CI 0.32-2.1), but non-ALD recipients had significantly lower risks (aHR 0.11; 95% CI 0.03-0.45).

Conclusion:

Our analysis of PEth results depicted different timing and risks of post-LT alcohol use between the three LT recipient groups. Prior studies suggested that self-reporting may underestimate actual alcohol use. Therefore, routine PEth testing, especially during the first 180 days post-LT, may help delineate alcohol use patterns to guide targeted addiction care.