UCSF

Background

Biomarkers can play a key role in supplementing self-report information in alcohol research. In this study, we examined phosphatidylethanol (PEth) in comparison with self-reported alcohol use over time in a randomized controlled trial.

Methods

Participants were women living with HIV enrolled in a randomized placebo-controlled trial of naltrexone for reducing hazardous drinking. Drinking behavior was measured using Timeline Followback (TLFB), and PEth as a biomarker using dried blood spots. Data collected at baseline, and months 2 and 7 were analyzed. In addition to calculated Spearman's correlations, mixed-effects modeling was used to evaluate the changes in self-reported drinking and PEth, respectively, adjusting for body mass index (BMI).

Results

A total of 194 participants (83% black, mean age 48) were included in the analysis. PEth levels were significantly correlated with self-reported drinking via TLFB, Spearman's r = 0.21 at baseline, r = 0.29 at 2 months, and r = 0.28 at 7 months, respectively. No demographic or health factors, except for BMI, was associated with whether self-report was consistent with PEth. Mixed-effects model indicated that self-reported drinking showed significantly greater reductions in the naltrexone treatment group than the placebo group at the 2- and 7-month visits, whereas PEth measure only showed this difference at the 7-month follow-up.

Conclusions

The magnitude of the correlation between PEth and self-reported alcohol consumption was small. Caution is needed when using either self-report or PEth as a sole outcome measure for alcohol behavior changes in clinical trials.