Blood-Alcohol Biomarkers Not a Substitute for Self-Report Among Young People with Injection Drug Use

Phosphatidylethanol (PEth) is an aberrant phospholipid found in cell membranes synthesized only in the presence of ethanol, and can be used as a biomarker of alcohol use. Researchers examined the correlation between self-reported alcohol use over the past month and PEth among <30 year-old people with injection drug use. Alcohol use was assessed with the AUDIT-C, and individuals were categorized as having probable DSM-IV dependence (score of 10–12), “hazardous” drinking (3–9 for women, 4–9 for men), or “low-risk” drinking (0–2 for women, 0–3 for men). Additional self-reported measures were: presence of any drinking, drinking until becoming unconscious, and heavy episodic drinking (defined as ≥6 drinks on an occasion).

• There was a strong correlation between PEth and self-reported alcohol use categories. PEth was elevated (≥8 ng/ml) in 89% of individuals categorized as having probable dependence, 61% of those with “hazardous” drinking, and 19% of those with “low-risk” drinking. PEth was not elevated in 12% of those with dependence, 39% of those with “hazardous” drinking, and 82% of those with “low-risk” drinking.
• For any alcohol consumption over the past month, PEth was elevated in 66% of people who reported consumption and not elevated in 94% of those who reported no consumption.
• PEth was elevated in 83% of those reporting drinking until becoming unconscious and 72% of those reporting heavy episodic drinking.

Comments:

As with other biomarkers, PEth’s use is likely limited. Even when crude self-reported estimations of drinking are used, PEth misses almost 40% of cases of self-reported hazardous drinking, and 17% of those reporting drinking until becoming unconscious. It is possible PEth would have performed better had the investigators used a higher cutoff but then detection (sensitivity) would have been even worse. Self-report appears to remain the most appropriate option to assess alcohol use in clinical populations.

Nicolas Bertholet, MD, MSc

Reference:

Jain J, Evans JL, Briceño A, et al. Comparison of phosphatidylethanol results to self-reported alcohol consumption among young injection drug users. Alcohol Alcohol. 2014;49(5):520–524.