Evaluation of phosphatidylethanol by ELISA for detection of excessive alcohol use compared with traditional biomarkers: a case-control study

Objective: The highly sensitive chromatographic methods for quantifying phosphatidylethanol (PEth) require high levels of expertice and expensive instrumentation. Enzyme-linked immunosorbent assay (ELISA) kits have been developed for research purposes, but the implementation of PEth immunoassays to screen alcohol consumption has not been applied to the analysis of clinical samples. Our aim was to examine the ELISA method for PEth analysis in clinical samples.

Methods: We examined the alterations of the PEth serum levels of 22 male inpatients diagnosed with alcohol dependence according to the Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition, during alcohol withdrawal (at days 1, 7, and 14) compared to 32 healthy controls using ELISA. All patients were admitted for detoxification treatment at the Alcohol and Substance Addiction Treatment and Rehabilitation Center, Trakya University School of Medicine, Edirne, Turkey. Control subjects were assessed with an initial clinical interview and screened with the Alcohol Use Disorder Identification Test (AUDIT), and they included 16 nondrinkers (AUDIT score = 0) and 16 social drinkers (AUDIT score < 8). We examined the diagnostic accuracy of PEth compared to the traditional biomarkers according to the receiver operating characteristic curve analysis.

Results: The patients undergoing detoxification had higher baseline PEth levels than the nondrinkers and social drinkers; the difference between groups showed a marginal trend towards significance (p = 0.052). PEth was correlated with the self-reported drinking amount in the past month and AUDIT scores, and the correlations showed marginal trends towards significance (rs = 0.269, p = 0.049; and rs = 0.266, p = 0.052; respectively). The PEth levels were statistically significantly correlated with gamma-glutamyl transferase (GGT) (rs = 0.355, p = 0.010), the correlations with alanine aminotransferase (ALT) and aspartate aminotransferase (AST) trended towards statistical significance (rs = 0.230, p = 0.095; and rs = 0.261, p = 0.056, respectively), and PEth was not statistically significantly correlated with mean corpuscular volume (MCV) (rs = 0.100, p = 0.478). PEth levels decreased statistically significantly during alcohol withdrawal (p = 0.002). PEth levels of the nondrinkers and social drinkers did not differ statistically significantly (p = 1.000). The area under the curve (AUC) for PEth measured by ELISA was statistically significantly higher than 0.5 (AUC = 0.691, p = 0.024), but PEth had poorer diagnostic efficacy than GGT (AUC = 0.933, p < 0.001), AST (AUC = 0.931, p < 0.001), MCV (AUC = 0.803, p < 0.001), and ALT (AUC = 0.789, p < 0.01).

Conclusions: The AUC of 0.69 shows that the diagnostic accuracy of the assay was poor, regardless of a statistical comparison to 0.5. The use of serum might have led to low concentrations that have not differed much between heavy drinkers and social drinkers or abstainers. Whole blood ELISA implementation for the quantification of PEth may increase its diagnostic efficacy