Table 4. Multivariable logistic regression modeling in the subgroup of patients with Day 1 plasma IL-6 concentrations available.

Dependent Variable	Independent Variable	Model 1	Model 2	Model 3
Day 3 AKI	Total FGF23	1.99 (1.44, 2.75), p<0.001	1.42 (0.95, 2.14), p = 0.09	1.26 (0.81, 1.96), p = 0.31
Day 60 mortality	Total FGF23	1.27 (0.92, 1.75), p = 0.14	1.38 (0.90, 2.11), p = 0.14	1.35 (0.88, 2.09), p = 0.17

This subgroup includes 135 subjects. In these models, the dependent variable is acute kidney injury (AKI) at three days post-ARDS diagnosis or mortality by 60 days post-ARDS diagnosis. The independent variable is Day 1 plasma total FGF23, which was log-transformed to correct for skewness. Model 1 is unadjusted. Model 2 is adjusted for age, sex, the presence or absence of Day 1 AKI, P/F ratio, and PRISM score. Model 3 is further adjusted for log-transformed Day 1 plasma IL-6. Data shown are odds ratios and 95% confidence intervals.