Improving the Model for End‐Stage Liver Disease with sodium by incorporating kidney dysfunction types

Abstract Background and Aims We investigated the impact of the inclusion of kidney dysfunction type on the discrimination and calibration of the Model for End‐Stage Liver Disease with sodium (MELD‐Na‐KT) score. Approach and Results We included all adults listed for ≥90 days without exception points from January 1, 2008, through December 31, 2018. We defined kidney dysfunction types as follows: acute kidney disease (AKD; an increase of ≥0.3 mg/dL or ≥50% in serum creatinine in the last 7 days or fewer than 72 days of hemodialysis), chronic kidney disease (CKD; an estimated glomerular filtration rate <60 ml/min/1.73 m 2 for 90 days or ≥72 days of hemodialysis), AKD on CKD (met both definitions), or none (met neither definition). We then developed and validated a multivariable survival model with follow‐up beginning at the first assessment after 90 days from waitlist registration and ending at the time of death, waitlist removal, or 90 days from enrollment in this study. The predictor variables were MELD‐Na and the derived MELD‐Na‐KT model. In the derivation cohort, kidney dysfunction type was significantly associated with waitlist mortality after controlling for MELD‐Na. There was a significant linear interaction between kidney dysfunction type and MELD‐Na score. In the validation cohort, we saw an improvement in the discrimination of the model with an increase in the c‐index from 0.76 with MELD‐Na to 0.78 with MELD‐Na‐KT ( p = 0.002) and a net reclassification index of 10.8% (95% CI, 1.9%–11.4%). The newly derived MELD‐Na‐KT model had lower Brier scores (MELD‐Na‐KT 0.042 vs. MELD‐Na 0.053). Conclusions This study demonstrates the feasibility and the potential for objectively defined kidney dysfunction types to enhance the prognostication of waitlist mortality provided by the MELD‐Na score.