Maximum Time Between Tests: A Digital Biomarker to Detect Therapy Compliance and Assess Schedule Quality in Measurement-Based eHealth Systems for Alcohol Use Disorder.

In a breathalyzer-based eHealth system for patients undergoing therapy for alcohol use disorder, the digital biomarker maximum time between tests' brings valuable information by predicting alcohol consumption as measured by biomarkers and timeline follow-back data. The digital biomarker can also identify the misuse of flexible test schedules. Abstract Aim To evaluate, in a breathalyzer-based eHealth system, whether the time-based digital biomarker maximum time between tests' (MTBT) brings valuable information on alcohol consumption patterns as confirmed by correlation with blood phosphatidyl ethanol (PEth), serum carbohydrate deficient transferrin (CDT) and timeline follow-back data. Method Data on 54 patients in follow-up for treatment of alcohol use disorder were analysed. Results The model of weekly averages of 24-log transformed MTBT adequately described timeline follow-back data (P < 0.0001, R = 0.27-0.38, n = 650). Significant correlations were noted between MTBT and PEth (P < 0.0001, R = 0.41, n = 148) and between MTBT and CDT (P < 0.0079, R = 0.22, n = 120). Conclusions The time-based digital biomarker maximum time between tests' described here has the potential to become a generally useful metric for all scheduled measurement-based eHealth systems to monitor test behaviour and compliance, factors important for dosing' of eHealth systems and for early prediction and interventions of lapse/relapse.