Table 2.
Alcohol Biomarkers With Univariable Characteristics and Variable Importance at Development/Internal Validation Site
| Biomarker | Univariable Raw Median Values (IQR) and Odds Ratios (95% CI) | Multivariable LASSO Biomarker Model Odds Ratio (95% CI) | Variable Importance Measure | |||
|---|---|---|---|---|---|---|
| No Unhealthy Alcohol Use | Unhealthy Alcohol Use | P-value | Univariable Odds Ratio | |||
| PEth (ng/mL) | 0.0 (0.0–19.0) | 227.0 (94.8–565.5) | <0.01 | 15.12 (14.43–15.81) | 8.82 (4.56–13.09) | 1.0 |
| BAC (mg/dL) | 0.0 (0.0–0.0) | 98.0 (0.0–227.0) | <0.01 | 4.52 (4.41–4.90) | 1.27 (0.80–1.74) | 1.0 |
| CDT (%) | 1.7 (1.5–1.9) | 2.1 (1.7–3.1) | <0.01 | 2.49 (2.14–2.84) | 1.04 (0.96–1.13) | 0.91 |
| GGT (units/L) | 18.0 (12.3–27.5) | 31.0 (21.0–70.0) | <0.01 | 2.69 (2.33–3.05) | 1.30 (0.79–1.81) | 0.80 |
| Urine EtS (ng/mL) | 0.0 (0.0–0.0) | 7060.6 (530.0–24130.0) | <0.01 | 5.47 (5.10–5.85) | Not selected | 0 |
| Urine EtG (ng/mL) | 0.0 (0.0–0.0) | 8933.6 (688.9–90005.1) | <0.01 | 5.57 (5.19–5.95) | Not selected | 0 |
Variable importance sums up the weights w k of the candidate model M k that contain the relevant variable with the measure averaged over the M imputed data sets. The Variable Importance measure is a range between 0 (unimportant) and 1 (very important). Based on variable important a 4-variable model with PEth, BAC, CDT, and GGT was chosen. Multivariable model derived with Least Absolute Shrinkage and Selection Operator (LASSO) to represent odds ratios for selected biomarkers with odds ratios (OR) reported as each standard deviation increase in the biomarker of interest. The variables in the multivariable model were log-transformed and multiply imputed with Rubin rule.
%CDT indicates percent serum carbohydrate deficient transferrin; EtG, urine ethyl glucuronide normalized with urinary creatinine; EtS, urine ethyl sulfate normalized for urinary creatinine; GGT, serum gamma-glutamyl-transpeptidase; PEth, phosphatidylethanol 16:0/18:1.