ABSTRACT
Background: This descriptive study of virtual contingency management tested changes of levels of PEth in blood and urinary EtG repeatedly across the study period at weekly, then monthly, intervals to evaluate incentives and the success of the intervention for alcohol use disorders. PEth in human red blood cells and uEtG aremetabolites of ethanol withmean half-lives during abstinence of approximately 7 days and several hours, respectively. The primary purpose of this analysis was to evaluate mean PEth levels when uEtG was either negative (undetectable) or positive. Also, increase or decrease of PEth levels when uEtG status changed was also tested. Methods: Community-dwelling participants (N = 11) with alcohol use disorders and baseline PEth levels ≥20ng/mL were recruited. Blood and urine samples were collected weekly for six weeks, monthly thereafter. Zoom-based supervision was used for participant, self-administered blood collection with TASSO-M20 devices. PEth was a continuous variable quantified with HPLC/MS/MS. uEtG levels were qualitatively tested with dip stick cards and reported as negative (undetectable) or positive (≥300 ng/mL). Results: Participants had from 6 to 17 virtual visits (total 11 subjects = 115 visits). Mean (SD) PEth level when uEtG levels ≥300 ng/mL (N = 63) was statistically greater than mean (SD) PEth level when uEtG levels were <300 ng/mL (undetectable;N = 45)], 856 (801) versus 91.2 (186) ng/mL, respectively (p <0.0001). Only 19/115 PEth values overlapped between the two uEtG groups. Change in direction of uEtG (up or down) between visits closely matched direction of PEth 19/23 times. uEtG levels did not change during 35 pairs of visits, but significant changes in PEth levels were still observed. Significant visit to visit changes in PEth occurred. xConclusions: Strong agreement existed between blood PEth and uEtG to indicate increase or decrease changes in alcohol consumption between virtual visits. The few discrepancies were likely related to the significant differences in the half-lives of the two direct biomarkers. Repeated within subject measurements at regular intervals enabled identification of changes in drinking between virtual visits. It should be noted that collection of blood with TASSO devices were self-administered by the participants to facilitate the continuation of this study during the COVID pandemic.