Table 1. Selection of experimental and comparator groups for analyses of waitlist outcomes of liver transplant waitlist candidates bypassed by simultaneous heart-liver recipients.

Analytic approach	Experimental group	Comparator group	Rationale
Matched candidate cohort #1	268 liver candidates ranked in the top 10 positions of a match run bypassed by a H-L recipient during the years 2007-2013	2,144 liver waitlist candidates matched 8:1 based on UNOS region, blood type, and match MELD score to bypassed liver waitlist candidates	Compare bypassed candidates to waitlist candidates with similar access to transplantation based on match MELD score
Matched candidate cohort #2	268 liver candidates ranked in the top 10 positions of a match run bypassed by a H-L recipient during the years 2007-2013	2,340 liver waitlist candidates matched 9:1 based on UNOS region, blood type, and laboratory MELD score to bypassed liver waitlist candidates	Compare bypassed candidates to waitlist candidates with similar risk of waitlist mortality based on laboratory MELD score
Matched allograft approach	268 liver candidates ranked in the top 10 positions of a match run bypassed by a H-L recipient during the years 2007-2013	20,962 liver waitlist candidates who were: 1) ranked in the top 10 of a match run of a liver-alone recipient who received a graft of similar quality to a H-L recipient; and 2) ranked higher than the organ recipient on that match run	Compare bypassed candidates to waitlist candidates on match runs of similar graft quality to “simulate” the outcomes had the liver in a H-L allocation been offered to a liver-alone candidate with the highest priority