The effect of the volume of procedures at transplantation centers on mortality after liver transplantation.

Background: For many complex surgical procedures there is an association be tween a low volume of procedures and an increased risk of death for the pat ients who undergo the procedures. Methods: We examined the effect of the volume of procedures at transplantat ion centers on the risk of death after liver transplantation. We analyzed a ll liver transplantations performed in the United States between October 1, 1987, and April 30, 1994. Because the results for 1987 to 1991 were largel y similar to those from 1992 to 1994, we focused on the more recent period. Results: Between January 1, 1992, and April 30, 1994, 47 centers performed 20 or fewer liver transplantations each per year (total, 837 transplantatio ns) and were designated low-volume centers, and 52 centers performed more t han 20 transplantations each per year (total, 6526) and were designated hig h-volume centers. The one-year mortality rate for the low-volume centers wa s 25.9 percent, as compared with 20.0 percent for the high-volume centers. Thirteen centers, all of which had low volumes, had one-year mortality rate s of more than 40 percent. Low-volume centers that were affiliated with hig h-volume centers, such as pediatric transplantation programs, had results s imilar to those of the high-volume centers. The one-year mortality rate at unaffiliated low-volume centers was 28.3 percent, as compared with a rate o f 20.1 percent for the group of all high-volume centers plus affiliated low -volume centers (P < 0.001). Conclusions: As a group, liver-transplantation centers in the United States that perform 20 or fewer transplantations per year have mortality rates th at are significantly higher than those at centers that perform more than 20 transplantations per year. Information regarding the outcome of liver tran splantation at transplantation centers should be made widely available to t he public. (N Engl J Med 1999;341:2049-53.) (C)1999, Massachusetts Medical Society.