Validation of the quantification of phosphatidylethanol 16:0/18:1 concentrations in TASSO-M20 devices.

Background: Phosphatidylethanol 16:0/18:1 (PEth), found in whole blood, is a biomarker for alcohol consumption with high sensitivity, specificity, and a long detection window. The TASSO-M20 device is used to self-collect capillary blood from the upper arm and has advantages over finger stick methods. The purpose of this study was to (1) validate PEth measurement using the TASSO-M20 device, (2) describe the TASSO-M20 for blood self-collection during a virtual intervention, and (3) characterize PEth, urinary ethyl glucuronide (uEtG) and self-reported alcohol in a single participant over time.

Methods: PEth levels in blood samples dried on TASSO-M20 plugs were compared to those in (1) liquid whole blood (N = 14) and (2) dried blood spot cards (DBS; N = 23). Additionally, the self-reported drinking, positive or negative uEtG results (dip card cutoff ≥300 ng/mL), and observed self-collection of blood with TASSO-M20 devices for PEth levels were obtained over time during virtual interviews of a single contingency management participant. High-performance liquid chromatography with tandem mass spectrometry detection was used to measure PEth levels for both preparations.

Results: PEth concentrations from dried blood on TASSO-M20 plugs and liquid whole blood were correlated (0 to 1700 ng/mL; N = 14; r  = 0.988; slope = 0.951) and in a subgroup of samples with lower concentrations (N = 7; 0 to 200 ng/mL; r  = 0.944, slope = 0.816). PEth concentrations from dried blood on TASSO-M20 plugs and DBS were correlated (0 to 2200 ng/mL; N = 23; r  = 0.927; slope = 0.667) and in a subgroup of samples with lower concentrations (N = 16; 0 to 180 ng/mL; r  = 0.978, slope = 0.749). Results of the contingency management participant indicate that changes in PEth levels (TASSO-M20) and uEtG concentrations were consistent with each other and with changes in self-reported alcohol use.

Conclusions: Our data support the utility, accuracy, and feasibility of using the TASSO-M20 device for blood self-collection during a virtual study. The TASSO-M20 device had multiple advantages over the typical finger stick method, including consistent blood collection, participant acceptability, and less discomfort as indicated by acceptability interviews.