Validating Self‐Reported Unhealthy Alcohol Use With Phosphatidylethanol (PEth) Among Patients With HIV

Background We sought to compare self‐reported alcohol consumption using Timeline Followback (TLFB) to biomarker‐based evidence of significant alcohol use (phosphatidylethanol [PEth] > 20 ng/ml). Using data from patients with HIV (PWH) entering a clinical trial, we asked whether TLFB could predict PEth > 20 ng/ml and assessed the magnitude of association between TLFB and PEth level. Methods We defined unhealthy alcohol use as any alcohol use in the presence of liver disease, at‐risk drinking, or alcohol use disorder. Self‐reported alcohol use obtained from TLFB interview was assessed as mean number of drinks/day and number of heavy drinking days over the past 21 days. Dried blood spot samples for PEth were collected at the interview. We used logistic regression to predict PEth > 20 ng/ml and Spearman correlation to quantify the association with PEth, both as a function of TLFB. Results Among 282 individuals (99% men) in the analytic sample, approximately two‐thirds (69%) of individuals had PEth > 20 ng/ml. The proportion with PEth > 20 ng/ml increased with increasing levels of self‐reported alcohol use; of the 190 patients with either at‐risk drinking or alcohol use disorder based on self‐report, 82% had PEth > 20 ng/ml. Discrimination was better with number of drinks per day than heavy drinking days (AUC: 0.80 [95% CI: 0.74 to 0.85] vs. 0.74 [95% CI: 0.68 to 0.80]). The number of drinks per day and PEth were significantly and positively correlated across all levels of alcohol use (Spearman’s R ranged from 0.29 to 0.56, all p values 20 ng/ml), and whether TLFB could discriminate individuals with evidence of significant alcohol by PEth. We found mean numbers of drinks/day discriminated individuals with PEth evidence of significant alcohol use. PEth complements self‐report to improve alcohol measurement in clinical settings and trials.