Faculty Bibliography

BACKGROUND: Kidney paired donation (KPD) offers the best transplant option for patients with incompatible live kidney donors. Although studies suggest substantial expansion of the donor pool if fully used, few patients in the United States have undergone KPD. METHODS: We analyzed the 209 KPD and 89 list paired donation (LPD) transplants reported to United Network for Organ Sharing to better understand access to these modalities, clinical outcomes, and areas of potential expansion. RESULTS: Although many centers offer KPD/LPD, most centers have performed no more than a handful of transplants. As expected, outcomes with KPD/LPD were equivalent to direct donation matched controls. In analyzing current practice, we identified two limitations to KPD in its current use. First, KPD is likely limited now by benefiting mostly patients who are easy to identify and match (such as A donors with B recipients or B donors with A recipients). Second, although some expansion of local KPD availability has reduced travel requirements for patients in those areas, significant room for growth remains. CONCLUSIONS: Our results suggest that full utilization of KPD would encourage registration of and improve matching for patients who are more difficult to identify and match (such as highly sensitized recipients). Furthermore, expansion of KPD would likely reduce travel requirements and thereby improve access to this treatment modality.

BACKGROUND: When the United Network for Organ Sharing changed its algorithm for liver allocation to the model for end-stage liver disease (MELD) system in 2002, highest priority shifted to patients with renal insufficiency as a major component of their end-stage liver disease. An unintended consequence of the new system was a rapid increase in the number of simultaneous liver-kidney transplants (SLK) being performed yearly. METHODS: Adult recipients of deceased donor liver transplants (LT, n=19,137), kidney transplants (n=33,712), and SLK transplants (n=1,032) between 1987 and 2006 were evaluated based on United Network for Organ Sharing data. Recipients were stratified by donor subgroup, MELD score, pre- versus post-MELD era, and length of time on dialysis. Matched-control analyses were performed, and graft and patient survival were analyzed by Kaplan-Meier and Cox proportional hazards analyses. RESULTS: MELD era outcomes demonstrate a decline in patient survival after SLK. Using matched-control analysis, we are unable to demonstrate a benefit in the SLK cohort compared with LT, despite the fact that higher quality allografts are being used for SLK. Subgroup analysis of the SLK cohort did demonstrate an increase in overall 1-year patient and liver graft survival only in those patients on long-term dialysis (> or =3 months) compared with LT (84.5% vs. 70.8%, P=0.008; hazards ratio 0.57 [95% CI 0.34, 0.95], P=0.03). CONCLUSION: These findings suggest that SLK may be overused in the MELD era and that current prioritization of kidney grafts to those liver failure patients results in wasting of limited resources.

Current billing practices and mandates to report surgical outcomes are disincentives to surgical treatment of obese patients, who are at increased risk for longer hospital stays and higher complication rates. The objective of this study was to quantify the independent association between body mass index (BMI) and waiting time for kidney transplantation to identify potential provider bias against surgical treatment of the obese. A secondary data analysis was performed of a prospective cohort of 132,353 patients who were registered for kidney transplantation in the United States between 1995 and 2006. Among all patients awaiting kidney transplantation, the likelihood of receiving a transplant decreased with increasing degree of obesity, categorized by ranges of BMI (adjusted hazard ratios 0.96 for overweight, 0.93 for obese, 0.72 for severely obese, and 0.56 for morbidly obese, compared with a reference group of patients with normal BMI). Similarly, the likelihood of being bypassed when an organ became available increased in a graded manner with category of obesity (adjusted incidence rate ratio 1.02 for overweight, 1.05 for obese, 1.11 for severely obese, and 1.22 for morbidly obese). Although matching an available organ with an appropriate recipient requires clinical judgment, which could not be fully captured in this study, the observed differences are dramatic and warrant further studies to understand this effect better and to design a system that is less susceptible to unintended bias.

CONTEXT: Although risks associated with live kidney donation are low, there are few pathologic studies of kidneys from live donors, and possible risk factors for development of hypertension or renal insufficiency remain unknown. There are many studies of histopathologic changes in deceased donor kidneys and how these changes affect subsequent graft function; most are based on wedge rather than needle core biopsies. OBJECTIVE: To examine the frequency and severity of arterial fibrointimal thickening and other pathologic lesions in kidneys from healthy live donors and compare wedge and needle core biopsies as methods for evaluating these changes. DESIGN: For 36 of 332 live donor renal transplantations performed from January 2004 through November 2006, a wedge biopsy of the transplanted kidney was done prior to and/or after implantation, and a needle core biopsy was done postimplantation or during the ensuing 7 days. For these 36 allografts, we compared pathologic features of the wedge and core perioperative biopsies. RESULTS: Findings on core and wedge biopsies were similar, except for arterial fibrointimal thickening. Moderate thickening (Banff cv2) was present on 13 core biopsies, and mild thickening (cv1) was present on another 10; by contrast, no wedge biopsies showed cv2 lesions, and only 8 showed cv1. Arterial thickening on core but not wedge biopsies correlated significantly with increasing patient age. CONCLUSIONS: The findings indicate that needle core biopsies are superior to wedge biopsies for evaluating vascular changes in donor kidneys, and they suggest a need for studies correlating such changes with long-term outcomes of live donors, particularly older donors.

Steroid use after liver transplantation (LT) has been associated with diabetes, hypertension, hyperlipidemia, obesity, and hepatitis C (HCV) recurrence. We performed meta-analysis and meta-regression of 30 publications representing 19 randomized trials that compared steroid-free with steroid-based immunosuppression (IS). There were no differences in death, graft loss, and infection. Steroid-free recipients demonstrated a trend toward reduced hypertension [relative risk (RR) 0.84, P = 0.08], and statistically significant decreases in cholesterol (standard mean difference -0.41, P < 0.001) and cytomegalovirus (RR 0.52, P = 0.001). In studies where steroids were replaced by another IS agent, the risks of diabetes (RR 0.29, P < 0.001), rejection (RR 0.68, P = 0.03), and severe rejection (RR 0.37, P = 0.001) were markedly lower in steroid-free arms. In studies in which steroids were not replaced, rejection rates were higher in steroid-free arms (RR 1.31, P = 0.02) and reduction of diabetes was attenuated (RR 0.74, P = 0.2). HCV recurrence was lower with steroid avoidance and, although no individual trial reached statistical significance, meta-analysis demonstrated this important effect (RR 0.90, P = 0.03). However, we emphasize the heterogeneity of trials performed to date and, as such, do not recommend basing clinical guidelines on our conclusions. We believe that a large, multicenter trial will better define the role of steroid-free regimens in LT.