eTable. Overview of the studies on phosphatidylethanol.

Study population/number	Aim/methods	Diagnostic information	Notes	References
Studies on PEth in selected patient populations
Patients with chronic liver disease (n = 222)	Self-evaluation. %CDT vs. PEth LC-MS/MS PEth 16:0/18:1 LOD: 8 ng/mL	Cut-off 80 ng/mL: sensitivity 91%. specificity 77% with ≥ 4 drinks/day in the last month	AUROC PEth: 0.90 AUROC %CDT: 0.79 supplementary to clinical assessment. relapse marker	(e15)
Outpatient alcohol withdrawal patients (n = 40). follow-up approx. 2 years	Monitoring. PEth. 9 homologs LC-MS/MS LOD. cut-off: 0.1µM Cut-off %CDT: 1.7%	Start: 70% Peth+. 55% CDT+ significant reduction in positive findings over time	PEth 16:0/18:1 is as sensitive as total PEth; relapse rate: PEth+ (43%). CDT+ (38%)	(e16)
HIV patients (n = 77) Blood collections at start and after 3 weeks	Checking of the amount drunk information. BrAC (daily) LC-MS/MS PEth 16:0/18:1 PEth 16:0/16:0 PEth 18:1/18:1 LOD: 10 ng/mL	Total patient population: Sensitivity: 88% Specificity: 88.5% ≥ 3 drinks/week: Sensitivity: 100% Specificity: 47.5% (LOD)	AUROC PEth 16:0/18:1: 0.92 > AUROC PEth 16:0/16:0 and 18:1/18:1; independent of age and BMI	(e17)
DBS of newborns (analysis up to 12 months after sample collection) (n = 250)	Prevalence. feasibility LC-MS/MS. PEth 16:0/18:1 LOD: 8 ng/mL	4% positive (PEth ≥ 8 ng/mL) Signs of alcohol consumption during last month of pregnancy	Reduction of PEth in DBS: ≤ 34.1% within a period of 12 months	(e18)
Patients before (n = 51) and after (n = 61) liver transplantation	Evaluation. comparison with other biomarkers LC-MS/MS PEth 16:0/18:1	Sensitivity PEth: 100 % Sensitivity ethanol. methanol and EtG (urine): 45–92 % last alcohol consumption ≤ 7 days	EtG in hair detects longer ago alcohol consumption	(25)
Women of reproductive age (n = 80)	Evaluation of PEth and alcohol consumption. LC-MS/MS PEth 16:0/18:1 or 18:1/16:0 LOD: 20 ng/mL (cut-off)	Significant association between alcohol amount and PEth 93% positive with ≥ 2 drinks/day	AUROC 0.77 (>1 drink/day) AUROC 0.80 (>2 drinks/day)	(e19)
Drivers in an interlock program (n = 147)	Compliance. comparison with other biomarkers LC/ELSD. LC-MS/MS LOD: 0.25 or. 0.005 µM	Ignition lock-out: LC-MS/MS: 88.5% positive. LC/ ELSD: 71.2% positive LC-MS/MS positive. even with no or very few lock-outs	Method comparison (MS/MS vs. ELSD): r2 = 0.86 PEth 16:0/18:1 ≈ 45% total PEth	(e20)
Selected prospective or experimental studies on PEth
moderate alcohol consumption (16 g women. 32 g men) (n = 44). Study duration: 3 months. no control group	Biomarker comparison LC-MS/MS PEth 16:0/18:1 LOD 3.5 ng/mL Cut-off %CDT 0.86%	PEth is always detectable after alcohol intake; Sensitivity: 100 % Specificity: 78 %	AUROC PEth: 0.92 AUROC %CDT: 0.82 The combination of PEth with %CDT does not result in an increase in AUROC.	(22)
Alcohol dose: 0.25 and 0.5 g/kg (n = 27). respectively; blood collections up to 14 days	Pharmacokinetics PEth 16:0/18:1 PEth 16:0/18:2 LC-MS/MS LOD: 5 ng/mL BrAC	PEth detected in all subjects. Cmax: 90–120 min. HL: 1.0–13.1 days. Samples with PEth 16:0/18:1 positive. but 16:0/18:2 negative. and vice versa	AUC (combined): overlapping between the doses; different formation and degradation rates of homologs; BrAC explains only 31% of PEth variability	(e21)
Alcohol dose: 1 g/kg (n = 16). blood collections up to 14 days	Window of detection after one-time consumption PEth 16:0/18:1 LC-/MS/MS EtG (urine)	Cmax: 37–208 ng/mL (8 h) mean HL: 3 days Detection period: 3–12 days		(e22)
Alcohol dose: 5 x 1 g/kg on 5 consecutive days (n = 11). Study duration: 16 days	Window of detection after repeated consumption PEth 16:0/18:1 LC-MS/MS BAC	PEth Cmax: 74–237 ng/mL (after 3–6 days) BACmax: 0.99–1.83 ‰	Low PEth concentrations compared to levels after alcohol abuse	(e23)

BrAC. breath alcohol concentration; AUROC. area under the receiver operating characteristic curve; BAC. blood alcohol concentration; BMI: body mass index;

CDT. carbohydrate-deficient transferrin; CDT+. CDT-positive cases; Cmax. maximum concentration; DBS. dried blood spot; EtG. ethyl glucuronide; HIV. human immunodeficiency virus;

HL. half-life; LC/ELSD. high-pressure liquid chromatography with an evaporative light-scattering detector; LC-MS/MS. high-pressure liquid chromatography-tandem mass spectrometry;

LOD. limit of detection; n. number of subjects; PEth. phosphatidylethanol; PEth+. positive PEth cases. The number combination behind the analyte identifies the PEth homolog (e.g. 16:0/18:1) used for the analysis (see eMethods).

Interlock program: Vehicle-integrated breath alcohol analyzer combined with an immobilizer. including traffic-psychological support for the driver