It is time to look inward

A typical patient of mine will have a better outcome if his or her liver transplant is performed at a higher volume program. That fact has been known for a number of years, and it seems to make sense to most people. After all, practice makes perfect, right? Unfortunately, it is not so simple in the real world. Not all patients are typical, very few donor organs are truly average in quality, and the performance of all transplant programs with a certain volume of activity is not uniform. Donor quality, an elusive concept, is partially quantified by the donor risk index (DRI) for livers recovered from deceased donors. The DRI is a composite measure that considers the following: the donor’s age, race/ethnicity, and height; the cause and type of death (eg, donation after cardiac death); the type of graft (whole versus partial); the donor’s location with respect to the local organ procurement organization service area; and the cold ischemia time. On average, for the typical patient, and at the typical liver transplant program, a higher DRI is associated with worse outcomes, and a lower DRI is associated with better outcomes. Lately, we have been experiencing a form of Lake Wobegon syndrome: all donated organs seem to be worse than average. Of course, this is not mathematically possible. However, the reverse is true: the average organ is getting worse, at least according to DRI measurements. This is not surprising because donor age is a prominent DRI component, and the donor population is aging along with the rest of us. How well are we doing with these higher DRI organs, and are higher volume programs particularly good at getting better results with them? In this issue of Liver Transplantation, Ozhathil et al. examine these questions and offer their take on the answers. They analyzed data from a cohort of US deceased donor liver transplants (2002-2008). They split the cohort according to the calculated DRIs: half had a DRI greater than 1.90, and the other half had a DRI less than or equal to 1.90. The heart of the analysis was focused on the half-cohort of 15,668 so-called high-DRI transplants, which perhaps would have been better termed higher DRI transplants. There were not large differences between the high-, medium-, and low-volume programs. The average unadjusted probabilities of a functioning liver transplant after 5 years were 60.3% at low-volume programs, 60.6% at medium-volume programs, and 62.6% at high-volume programs. The corresponding probabilities of being alive were 64.7%, 66.8%, and 68.3%. In all likelihood, the ranges of these results overlapped across the 3 program volume tertiles, although these data are not reported. Moreover, it is likely that some individual lowor medium-volume programs achieved better results than certain highvolume programs did, as previously reported by Axelrod et al. Programs should not be judged purely on the basis of their volume. Multivariate statistical models were used to adjust for differences in patient and program characteristics that might have affected the outcomes of interest and to gauge relative outcomes. This is the ‘‘compared to what’’ question. A higher DRI within the higher DRI half-cohort was associated with significantly higher risks of graft failure and patient death in comparison with a lower DRI (again within the higher DRI halfcohort). A higher annual center volume was also