Random forest analysis identifies change in serum creatinine and listing status as the most predictive variables of an outcome for young children on liver transplant waitlist

Abstract

Young children listed for liver transplant have high waitlist mortality (WL), which is not fully predicted by the PELD score. SRTR database was queried for children < 2 years listed for initial LT during 2002-17 (n = 4973). Subjects were divided into three outcome groups: bad (death or removal for too sick to transplant), good (spontaneous improvement), and transplant. Demographic, clinical, listing history, and laboratory variables at the time of listing (baseline variables), and changes in variables between listing and prior to outcome (trajectory variables) were analyzed using random forest (RF) analysis. 81.5% candidates underwent LT, and 12.3% had bad outcome. RF model including both baseline and trajectory variables improved prediction compared to model using baseline variables alone. RF analyses identified change in serum creatinine and listing status as the most predictive variables. 80% of subjects listed with a PELD score at time of listing and outcome underwent LT, while ~70% of subjects in both bad and good outcome groups were listed with either Status 1 (A or B) prior to an outcome, regardless of initial listing status. Increase in creatinine on LT waitlist was predictive of bad outcome. Longer time spent on WL was predictive of good outcome. Subjects with biliary atresia, liver tumors, and metabolic disease had LT rate >85%, while >20% of subjects with acute liver failure had a bad outcome. Change in creatinine, listing status, need for RRT, time spent on LT waitlist, and diagnoses were the most predictive variables.

Keywords: infant; liver transplant; machine learning; outcome; pediatric; random forest analysis; waitlist.

Figure 1:

Dot Plot showing the results of Random Forest Analysis using baseline variables only (A) and both baseline and trajectory variables (B). Variables are listed on the Y-axis, and variable importance scores are indicated on the X-axis (BA – Biliary Atresia, PELD – Pediatric End-Stage Liver Disease, INR – International Normalized Ratio, Renal Replacement Therapy – Development of need for renal replacement therapy on waitlist, not present at listing, Growth failure – Development of growth failure on waitlist, not present at listing).

Figure 2:

A stacked bar chart showing the percentage of subjects in each outcome across various major diagnostic groups. (*BA = Biliary atresia)

Figure 3:

Bar chart showing the distribution of subjects with the various permutations of change of listing status based on final outcomes (first status –status at listing, last status – status at outcome, 1A/B – listed with Status 1 (A or B), PELD – listed with PELD score).