Strong concordance and correlation between direct alcohol biomarkers and alcohol self-report among youth with variable drinking patterns.

Abstract

Heavy drinking among adolescents is associated with various consequences but is often undetected, limiting early intervention. Self-report of alcohol use has strengths but can be inaccurate due to recall biases and underreporting. Objective biomarkers may improve detection of drinking and related consequences, but few adolescent studies have assessed biomarker concordance with subjective self-report. Youth aged 15-19 (54 % female) with minimal (n = 22) or heavy (n = 56) drinking patterns attended two research-related visits, approximately 13 days apart. Biospecimens were collected at both visits for urine ethylglucuronide (EtG) quantification (100ng/ml cutoff) and at visit two for whole blood phosphatidylethanol (PEth) quantification (20ng/ml cutoff). Cohen's Kappa concordance and Spearman's Rank Order correlations compared biomarkers and self-report drinking via Timeline Follow-back method. Exploratory analyses evaluated whether PEth improved model accuracy for alcohol-related severity outcomes beyond self-report. EtG had moderate concordance with any prior 2- or 3-day drinking (κ=.46-.53) at visit one but had substantial concordance by visit two (κ=.66-.80). PEth showed substantial concordance with any drinking (κ=.63-.66) and was strongly correlated with total drinks (r_s=.80-.82) in prior 2- or 4-weeks. PEth and self-report drinking were not consistently associated with severity outcomes, although PEth improved model accuracy for select outcomes. Findings largely support agreement of biomarkers with adolescent reported drinking in a research context without contingent rewards or punishments. Results suggest that collection of alcohol biomarkers may be most informative at an initial appointment to inform study eligibility. Quantity of alcohol consumption alone did not adequately account for youth-reported alcohol-related consequences.