Here's the article, forthcoming in the American Journal of Transplantation:
Broken Chains and Reneging: A Review of 1,748 Kidney Paired Donation Transplants
Nick Cowan, H. Albin Gritsch, Nima Nisseri, Joe Sinacore, Jeffrey Veale
Accepted manuscript online: 10 May 2017
Abstract: Concerns regarding the potential for broken chains and reneges within kidney paired donation (KPD) and its effect on chain length have been previously raised. While these concerns have been tested in simulation studies, “real world” data has yet to be evaluated. The purpose of this study was to evaluate the actual rate and cause of broken chains within a large KPD program. All patients undergoing renal transplantation through the National Kidney Registry from 2008 through May 2016 were included for analysis. Broken chains and loops were identified. A total of 344 chains and 78 loops were completed during the study period yielding a total of 1,748 transplants. Twenty broken chains and one broken loop were identified. The mean chain length (# of transplants) within broken chains was 4.8 compared to 4.6 of completed chains (p=0.78). The most common causes of a broken chain were donor medical issues incurred while acting as a bridge donor (n=8), donors electing not to proceed (n=6), and kidneys being declined by the recipient surgeon (n=4). All recipients involved in a broken chain have subsequently received a transplant. Based on the results broken chains are infrequent, rarely due to lack of donor motivation, and have no significant impact on chain length.