Determining Ethyl Glucuronide Cutoffs When Detecting Self‐Reported Alcohol Use in Addiction Treatment Patients

Abstract

Background Ethyl glucuronide (EtG) is an alcohol biomarker with potential utility as a clinical research and alcohol treatment outcome. Debate exists regarding the appropriate cutoff level for determining alcohol use, particularly with the EtG immunoassay. This study determined the EtG immunoassay cutoff levels that most closely correspond to self-reported drinking in alcohol dependent outpatients. Methods Eighty adults with alcohol dependence and mental illness, taking part in an alcohol treatment study, provided urine samples three times per week for up to 16-weeks (1589 samples). Self-reported drinking during 120 hours prior to each sample collection was assessed. Receiver Operating Characteristic analyses were conducted to assess the ability of the EtG immunoassay to detect self-reported alcohol use across 24–120 hour time periods. Sensitivity and specificity of EtG immunoassay cutoff levels was compared in 100 ng/mL increments (100 ng/mL–500 ng/mL) across 24–120 hours. Results Over half (57%) of the 1589 samples indicated recent alcohol consumption. The EtG immunoassay closely corresponded to self-reported drinking from 24 (AUC=0.90, 95% CI:0.88, 0.92) to 120 hours (AUC=0.88, 95% CI:0.87, 0.90). When cutoff levels were compared across 24–120 hours, 100 ng/mL had the highest sensitivity (0.93–0.78) and lowest specificity (0.67–0.85). Relative to 100 ng/mL, the 200 ng/mL cutoff demonstrated a reduction in sensitivity (0.89–0.67), but improved specificity (0.78–0.94). The 300 ng/mL, 400 ng/mL, and 500 ng/mL cutoffs demonstrated the lowest sensitivity (0.86 to 0.33) and highest specificity (0.86–0.97) over 24 to 120 hours. Conclusions For detecting alcohol use for greater than 24 hours, the 200 ng/mL cutoff level is recommended for use as a research and clinical outcome.

A culturally-tailored behavioral intervention trial for alcohol use disorders in three American Indian communities: Rationale, design, and methods

“…Previous research on CM for AUDs has been limited by lack of such a biomarker. Ethyl glucuronide (EtG) is an alcohol metabolite [22–31] that can be detected in urine for up to five days after drinking and can be evaluated in a clinical setting using a benchtop analyzer [29,32–35]. Our work supports the efficacy and feasibility of an EtG-based CM intervention [36].…”

“…Consistent with our previous studies recent alcohol use will be defined as an EtG> 150 ng/mL. Our previous studies suggest that this cutoff level is not associated with “false positives” resulting from exposure to non-beverage alcohol (e.g., hand sanitizer, mouthwash) [35]. Despite the low risk of false positive tests, participants will be reminded that they should abstain from all alcohol-containing products.…”

Urine Ethyl Glucuronide Unraveling the Reality of Abstinence Monitoring in a Routine Outpatient Setting: A Cross-Sectional Comparison with Ethanol, Self Report and Clinical Judgment

“…However, this might account only for a residual number of positives. Also, despite the fact that some previous research indicates that a cut-off of 500 ng/ml might produce a relative high risk of unintended positives [36] , other recent studies suggest that the specificity of EtG remains acceptably high with this cut-off [37] . Also, EtG/ creatinine ratios and EtG-LC-MS/MS confirmation tests were not conducted.…”

Using a randomized controlled trial to test whether modifications to contingency management improve outcomes for heavy drinkers with serious mental illness

“…Recent heavy drinking will also be assessed by uEtG tests with a cut-off of uEtG > 349 ng/mL during the indication phase and a cut-off of uEtG > 499 ng/mL for participants randomized to the Shaping CM condition [22]. Although the use of alcohol-containing products has not been associated with false positives [22,40], participants will be asked to abstain from using all alcohol-containing products (i.e., hand sanitizer). Urine samples will be tested for opioids (morphine > 2000 ng/ mL), amphetamine (D-amphetamine > 1000 ng/mL), methamphetamine (D-methamphetamine > 1000 ng/mL), cocaine benzoylecgonine > 300 ng/mL, and cannabis (tetrahydrocannabinol > 50 ng/mL) with EZ-split point-of-care immunoassays at each study visit.…”