Impact of Centers for Medicare and Medicaid Services Final Rule on Organ Procurement Organization Metrics and Procedural Trends in the Procurement of Pancreata for Research.

OBJECTIVE: Pancreata recovered for research are included as a success (or positive) in the Centers for Medicare and Medicaid Services' (CMS) donation and organ transplantation rate metrics for recertification of organ procurement organizations (OPOs). MATERIALS AND METHODS: Given these metrics directly incentivize recovery of pancreata for research, this study tracks trends in recovery of pancreata for research across the implementation of the CMS metrics. RESULTS: In the 26 months before the December 2, 2020, publication of the CMS metrics, research pancreata as a percent of organs transplanted, including research pancreata, was 1.7% nationally, including as much as 10.8% of organs transplanted within any OPO. In the 26 months after the CMS metrics were published, research pancreata increased to 5.1% of organs counted as transplants nationally, including as much as 20.3% within any OPO. If research pancreata were excluded from the CMS metrics, 6 OPOs would change their CMS evaluation status for recertification purposes: 2 would move up a tier and 4 would move down a tier. CONCLUSIONS: Procurement of research pancreata has increased since the publication of the CMS performance metrics, OPOs vary in their recovery of pancreata for research, and recovery of pancreata for research can affect recertification of OPOs.

OPTN/SRTR 2021 Annual Data Report: Deceased Organ Donation.

The Scientific Registry of Transplant Recipients uses data collected by the Organ Procurement and Transplantation Network to calculate metrics such as donation rate, organ yield, and rate of organs recovered for transplant but not transplanted (ie, nonuse). In 2021, there were 13,862 deceased donors, a 10.1% increase from 12,588 in 2020, and an increase from 11,870 in 2019; this number has been increasing since 2010. The number of deceased donor transplants increased to 41,346 transplants in 2021, a 5.9% increase from 39,028 in 2020; this number has been increasing since 2012. The increase may be due in part to the rising number of deaths of young people amid the ongoing opioid epidemic. The number of organs transplanted included 9,702 left kidneys, 9,509 right kidneys, 551 en bloc kidneys, 964 pancreata, 8,595 livers, 96 intestines, 3,861 hearts, and 2,443 lungs. Compared with 2019, transplants of all organs except lungs increased in 2021, which is remarkable as this occurred despite the COVID-19 pandemic. In 2021, 2,951 left kidneys, 3,149 right kidneys, 184 en bloc kidneys, 343 pancreata, 945 liver, 1 intestine, 39 hearts, and 188 lungs were not used. These numbers suggest an opportunity to increase numbers of transplants by reducing nonused organs. Despite the pandemic, there was no dramatic increase in number of nonused organs and there was an increase in total numbers of donors and transplants. The new Centers for Medicare & Medicaid Services metrics for donation rate and transplant rate have also been described and vary across organ procurement organizations; the donation rate metric varied from 5.82 to 19.14 and the transplant rate metric varied from 18.7 to 60.0.

OPTN/SRTR 2021 Annual Data Report: Lung.

The number of lung transplants has continued to decline since 2020, a period that coincides with the onset of the COVID-19 pandemic. Lung allocation policy continues to undergo considerable change in preparation for adoption of the Composite Allocation Score system in 2023, beginning with multiple adaptations to the calculation of the Lung Allocation Score that occurred in 2021. The number of candidates added to the waiting list increased after a decline in 2020, while waitlist mortality has increased slightly with a decreased number of transplants. Time to transplant continues to improve, with 38.0% of candidates waiting fewer than 90 days for a transplant. Posttransplant survival remains stable, with 85.3% of transplant recipients surviving to 1 year; 67%, to 3 years; and 54.3%, to 5 years.

The need for integrated clinical and administrative data models for risk adjustment in assessment of the cost transplant care.

INTRODUCTION: Value-based purchasing requires accurate techniques to appropriately measure both outcomes and cost with robust adjustment for differences in severity of illness. Traditional methods to adjust cost estimates have exclusively used administrative data derived from billing claims to identify comorbidity and complications. Transplantation uniquely has accurate national clinical registry data that can be used to supplement administrative data. METHODS: Administrative claims from the Vizient, Inc, Clinical Data Base (CDB) were linked with clinical records from the Scientific Registry for Transplant Recipients for 76 liver and 109 kidney transplant programs. Using either or both datasets, we fitted a regression model to the total direct cost of care for 16,649 kidney and 6058 liver transplants. RESULTS: The proportion of variation explained by these risk-adjustment models increased significantly when combined administrative and clinical data were used for kidney (administrative only R2 = .069, clinical only R2 = .047, combined R2 = .14, p < .0001) and liver (administrative only R2 = .28, clinical only R2 = .25, combined R2 = .33, p < .0001). CONCLUSION: Incorporating accurate clinical data into risk-adjustment methodologies can improve risk adjustment methodologies; however, as majority of variation in cost remains unexplained by these risk-adjustment models further work is needed to accuracy assess transplant value.

The Centers for Medicare and Medicaid Services' proposed metrics for recertification of organ procurement organizations: Evaluation by the Scientific Registry of Transplant Recipients.

On December 23, 2019, the US Centers for Medicare and Medicaid Services proposed 2 new standards that organ procurement organizations (OPOs) must meet for recertification. An OPO's organ donation rate (deceased donors/potential donors) and organ transplant rate (organs transplanted/potential donors) must not fall significantly below the 75th percentile for rates among all OPOs. We examined how OPOs would have fared under the proposed performance standards in 2016-2017. Data on donors and transplants were from the Organ Procurement and Transplantation Network; donor potential was estimated from Detailed Multiple Cause of Death data collected by the Centers for Disease Control and Prevention. In 2017, 31 (53%) OPOs failed to meet the proposed donation rate standard, 36 (62%) failed to meet the proposed organ transplant rate standard, and 37 (64%) failed at least 1 standard. We found that adjusting for age, race, and Hispanic ethnicity altered the evaluation: 8 OPOs changed their pass/fail status for the donation rate and 5 for the proposed organ transplant rate standard. We conclude that the proposed new standards may result in over half of OPOs facing decertification, and risk adjustment suggests that underlying characteristics of deaths vary regionally such that decertification decisions may be affected.

Risk of ESKD in Older Live Kidney Donors with Hypertension.

BACKGROUND AND OBJECTIVES: Hypertension in older kidney donor candidates is viewed as safe. However, hypertension guidelines have evolved and long-term outcomes have not been explored. We sought to quantify the 15-year risk of ESKD and mortality in older donors (≥50 years old) with versus those without hypertension. DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS: A United States cohort of 24,533 older donors from 1999 to 2016, including 2265 with predonation hypertension, were linked to Centers for Medicare and Medicaid Services data and the Social Security Death Master File to ascertain ESKD development and mortality. The exposure of interest was predonation hypertension. From 2004 to 2016, hypertension was defined as documented predonation use of antihypertensive therapy, regardless of systolic BP or diastolic BP; from 1999 to 2003, when there was no documentation of antihypertensive therapy, hypertension was defined as predonation systolic BP ≥140 or diastolic BP ≥90 mm Hg. RESULTS: Older donors were 82% white, 6% black, 7% Hispanic, and 3% Asian. The median follow-up was 7.1 years (interquartile range, 3.4-11.1; maximum, 18). There were 24 ESKD and 252 death events during the study period. The 15-year risk of ESKD was 0.8% (95% confidence interval [95% CI], 0.4 to 1.6) for donors with hypertension (mean systolic BP, 138 mm Hg) versus 0.2% (95% CI, 0.1 to 0.4) for donors without hypertension (mean systolic BP, 123 mm Hg; adjusted hazard ratio, 3.04; 95% CI, 1.28 to 7.22; P=0.01). When predonation antihypertensive therapy was available, the risk of ESKD was 6.21-fold higher (95% CI, 1.20 to 32.17; P=0.03) for donors using antihypertensive therapy (mean systolic BP, 132 mm Hg) versus those not using antihypertensive therapy (mean systolic BP, 124 mm Hg). There was no significant association between donor hypertension and 15-year mortality (hazard ratio, 1.18; 95% CI, 0.84 to 1.66; P=0.34). CONCLUSIONS: Compared with older donors without hypertension, older donors with hypertension had higher risk of ESKD, but not mortality, for 15 years postdonation. However, the absolute risk of ESKD was small.

The association between loss of Medicare, immunosuppressive medication use, and kidney transplant outcomes.

Kidney transplant recipients aged <65 years qualify for Medicare coverage, but coverage ends 3 years posttransplant. We determined the association between timing of Medicare loss and immunosuppressive medication fills and kidney allograft loss. Using data from the Scientific Registry of Transplant Recipients (SRTR), US Renal Data System, and Symphony pharmacy fill database, we analyzed 78 861 Medicare-covered, kidney-alone recipients aged <65 years, and assessed the timing of Medicare loss posttransplant: early (<3 years), on-time (at 3 years), or late (>3 years). Immunosuppressant use was measured as medication possession ratio (MPR). Allograft loss was assessed using SRTR data. MPR was lower for recipients with early or late Medicare loss compared with no coverage loss for all immunosuppressive medication types. For calcineurin inhibitors, early Medicare loss was associated with a 53% to 86% lower MPR. On-time Medicare loss was not associated with a lower MPR. When recipients were matched by age, posttransplant timing of Medicare loss, and donor risk, the hazard of allograft loss was 990% to 1630% higher after early Medicare loss, and 140% to 740% higher after late Medicare loss, with no difference in the hazard for on-time Medicare loss. Ensuring ongoing Medicare access before and after 3 years posttransplant could affect graft survival.

How patients choose kidney transplant centers: A qualitative study of patient experiences.

Little is known about how patients make the critical decision of choosing a transplant center. In the United States, acceptance criteria, waiting times, and mortality vary significantly by geography and center. We sought to understand patients' experiences and perspectives when selecting transplant centers. We included 82 kidney transplant patients in 20 semi-structured interviews, nine focus groups with local candidates, and three focus groups with national recipients. Sites included two local transplant centers in Minneapolis, Minnesota, and national recipients from across the United States. Transcripts were analyzed by two researchers using a thematic analysis. Several themes emerged related to priorities and barriers when choosing a center. Patients were often unfamiliar with options, even with multiple local centers. Patients described being referred to a specific center by a trusted provider. Patients prioritized perceived reputation, comfort, and convenience. Insurance coverage was both a source of information and a barrier to options. Patients underestimated differences across centers and the effects on being waitlisted and receiving a transplant. Barriers in decision making included an overwhelming scope of information and difficulty locating information relevant to patients with unique medical needs. Informed decisions could be improved by the dissemination of understandable information better tailored to individual patient needs.

Organ distribution without geographic boundaries: A possible framework for organ allocation.

The Final Rule mandates that organ allocation not be based on the transplant candidate's place of residence or listing, except as required by sound medical judgment and best use of donated organs, to avoid wasting organs and futile transplants, and to promote access and efficiency. Current Organ Procurement and Transplantation Network (OPTN) policies use donation service areas and OPTN regions to distribute and allocate organs for transplant. These policies have recently been called into question as not meeting the requirements of the Final Rule. Therefore, we propose using borderless allocation scores that combine medical priority scores with geographic feasibility scores. Medical priority scores are currently used in OPTN allocation policy, for example, the model for end-stage liver disease and the lung allocation score. Geographic feasibility scores can be developed to account for the effects of ischemia due to travel times, donor characteristics that modify the feasibility of traveling due to organ outcomes, and the costs of shipping organs over long distances. A borderless distribution and allocation system could address the goals of equity and utility, while fulfilling the mandates of the Final Rule and providing optimal use of a scare resource.

Heart and lung organ offer acceptance practices of transplant programs are associated with waitlist mortality and organ yield.

Variation in heart and lung offer acceptance practices may affect numbers of transplanted organs and create variability in waitlist mortality. To investigate these issues, offer acceptance ratios, or adjusted odds ratios, for heart and lung transplant programs individually and for all programs within donation service areas (DSAs) were estimated using offers from donors recovered July 1, 2016, and June 30, 2017. Logistic regressions estimated the association of DSA-level offer acceptance ratios with donor yield and local placement of organs recovered in the DSA. Competing risk methodology estimated the association of program-level offer acceptance ratios with incidence and rate of waitlist removals due to death or becoming too sick to undergo transplant. Higher DSA-level offer acceptance was associated with higher yield (odds ratios [ORs]: lung, 1.04 1.111.19 ; heart, 1.09 1.211.35 ) and more local placement of transplanted organs (ORs: lung, 1.01 1.121.24 ; heart, 1.47 1.691.93 ). Higher program-level offer acceptance was associated with lower incidence of waitlist removal due to death or becoming too sick to undergo transplant (hazard ratios [HRs]: heart, 0.80 0.860.93 ; lung, 0.67 0.750.83 ), but not with rate of waitlist removal (HRs: heart, 0.91 0.981.06 ; lung, 0.89 0.991.10 ). Heart and lung offer acceptance practices affected numbers of transplanted organs and contributed to program-level variability in the probability of waitlist mortality.

Liver Simulated Allocation Modeling: Were the Predictions Accurate for Share 35?

BACKGROUND: The liver simulated allocation model (LSAM) can be used to study likely effects of liver transplant allocation policy changes on organ offers, acceptance, waitlist survival, and posttransplant survival. Implementation of Share 35 in June 2013 allowed for testing how well LSAM predicted actual changes. METHODS: LSAM projections for 1 year of liver transplants before and after the Share 35 policy change were compared with observed data during the same period. Numbers of organs recovered, organ sharing, transplant rates, and waitlist mortality rates (per 100 waitlist years) were evaluated by LSAM and compared with observed data. RESULTS: Candidate, recipient, and donor characteristics in the LSAM cohorts were similar to those in the observed population before and after Share 35. LSAM correctly predicted more accepted organs and fewer discarded organs with Share 35. LSAM also predicted increased regional and national sharing, consistent with observed data, although the magnitude was overestimated. Transplant rates were correctly projected to increase and waitlist death rates to decrease. CONCLUSIONS: Although the absolute number of transplants was underestimated and waitlist deaths overestimated, the direction of change was consistent with observed data. LSAM correctly predicted change in discarded organs, regional and national sharing, waitlist mortality, and transplants after Share 35 implementation.

Influence of kidney offer acceptance behavior on metrics of allocation efficiency.

We investigated associations of deceased donor kidney offer acceptance with likelihood of the kidney being discarded, cold ischemia time at transplant (CIT), and likelihood of the kidney being exported outside the donation service area (DSA). We used kidney offers from donors in the Scientific Registry of Transplant Recipients July 1, 2015-June 30, 2016, and a stratified logistic regression to estimate odds ratios of acceptance for candidates wait-listed in a DSA. We estimated associations between these ratios and likelihood of discard or export and CIT at transplant. Approximately 0.50 kidneys were discarded per donor; lower DSA-specific offer acceptance ratios were associated with more discards (R=-0.20; P=0.006). For a median donor, the DSA with the highest acceptance ratio would place 0.12 more kidneys per donor than the DSA with the lowest ratio. Low acceptance ratios were associated with higher CIT (R=-0.23; P<0.001). For the median donor, CIT was 2.9 hours shorter for the DSA with the highest versus lowest acceptance ratio. Low acceptance ratios were associated with more exports (R=-0.43; P<0.001); the probability was 15% higher for a median donor in the DSA with the lowest versus highest acceptance ratio. Improving lower-than-expected offer acceptance would likely reduce discards, CIT, and exports.

Allocating Deceased Donor Kidneys to Candidates with High Panel-Reactive Antibodies.

BACKGROUND AND OBJECTIVES: In December of 2014, the Organ Procurement and Transplant Network implemented a new Kidney Allocation System (KAS) for deceased donor transplant, with increased priority for highly sensitized candidates (calculated panel-reactive antibody [cPRA] >99%). We used a modified version of the new KAS to address issues of access and equity for these candidates. DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS: In a simulation, 10,988 deceased donor kidneys transplanted into waitlisted recipients in 2010 were instead allocated to candidates with cPRA≥80% (n=18,004). Each candidate's unacceptable donor HLA antigens had been entered into the allocation system by the transplant center. In simulated match runs, kidneys were allocated sequentially to adult ABO identical or permissible candidates with cPRA 100%, 99%, 98%, etc. to 80%. Allocations were restricted to donor/recipient pairs with negative virtual crossmatches. RESULTS: The simulation indicated that 2111 of 10,988 kidneys (19.2%) would have been allocated to patients with cPRA 100% versus 74 of 10,988 (0.7%) that were actually transplanted. Of cPRA 100% candidates, 74% were predicted to be compatible with an average of six deceased donors; the remaining 26% seemed to be incompatible with every deceased donor organ that entered the system. Of kidneys actually allocated to cPRA 100% candidates in 2010, 66% (49 of 74) were six-antigen HLA matched/zero-antigen mismatched (HLA-A, -B, and -DR) with their recipients versus only 11% (237 of 2111) in the simulation. The simulation predicted that 10,356 of 14,433 (72%) candidates with cPRA 90%-100% could be allocated an organ compared with 7.3% who actually underwent transplant. CONCLUSIONS: Data in this simulation are consistent with early results of the new KAS; specifically, nearly 20% of deceased donor kidneys were (virtually) compatible with cPRA 100% candidates. Although most of these candidates were predicted to be compatible with multiple donors, approximately one-quarter are unlikely to receive a single offer.

Cost Implications of New National Allocation Policy for Deceased Donor Kidneys in the United States.

BACKGROUND: In December 2014, a new national deceased donor kidney allocation policy was implemented, which allocates kidneys in the top 20% of the kidney donor profile index to candidates in the top 20% of expected survival. We examined the cost implications of this policy change. METHODS: A Markov model was applied to estimate differences in total lifetime cost of care and quality-adjusted life years (QALY). RESULTS: Under the old allocation policy, average lifetime outcomes per listed patient discounted to 2012 US dollars were US $342,799 and 5.42 QALY, yielding US $63,775 per QALY gained. Under the new policy, average lifetime cost was reduced by US $2090 and lifetime QALYs increased by 0.03. Thus, the new policy improved on the old policy by producing more QALYs at lower cost. The present value of total lifetime cost savings from the policy change is estimated to be US $271 million in the first year and US $55 million in subsequent years. The higher transplant rates and allograft survival expected for candidates in the top 20% of expected survival would decrease costs by reducing time on dialysis. Most cost savings are expected to accrue to Medicare, and most increased access to transplant is expected in private payer populations. CONCLUSIONS: The new allocation policy was found to be dominant over the old policy because it increases QALYs at lower cost.

Liver sharing and organ procurement organization performance under redistricted allocation.

Concerns have been raised that optimized redistricting of liver allocation areas might have the unintended result of shifting livers from better-performing to poorer-performing organ procurement organizations (OPOs). We used liver simulated allocation modeling to simulate a 5-year period of liver sharing within either 4 or 8 optimized districts. We investigated whether each OPO's net liver import under redistricting would be correlated with 2 OPO performance metrics (observed to expected liver yield and liver donor conversion ratio), along with 2 other potential correlates (eligible deaths and incident listings above a Model for End-Stage Liver Disease score of 15). We found no evidence that livers would flow from better-performing OPOs to poorer-performing OPOs in either redistricting scenario. Instead, under these optimized redistricting plans, our simulations suggest that livers would flow from OPOs with more-than-expected eligible deaths toward those with fewer-than-expected eligible deaths and that livers would flow from OPOs with fewer-than-expected incident listings to those with more-than-expected incident listings; the latter is a pattern that is already established in the current allocation system. Redistricting liver distribution to reduce geographic inequity is expected to align liver allocation across the country with the distribution of supply and demand rather than transferring livers from better-performing OPOs to poorer-performing OPOs.

Variation in Cost and Quality in Kidney Transplantation.

BACKGROUND: Bending the cost curve in medical expenses is a high national priority. The relationship between cost and kidney allograft failure has not been fully investigated in the United States. METHODS: Using Medicare claims from the United States Renal Data System, we determined costs for all adults with Medicare coverage who underwent kidney transplant January 1, 2007, to June 30, 2009. We compared relative cost (observed/expected payment) for year 1 after transplantation for all transplant centers, adjusting for recipient, donor, and transplant characteristics, region, and local wage index. Using program-specific reports from the Scientific Registry of Transplant Recipients, we correlated relative cost with observed/expected allograft failure between centers, excluding small centers. RESULTS: Among 19,603 transplants at 166 centers, mean observed cost per patient per center was $65,366 (interquartile range, $55,094-$71,624). Mean relative cost was 0.99 (± 0.20); mean observed/expected allograft failure was 1.03 (± 0.46). Overall, there was no correlation between relative cost and observed/expected allograft failure (r = 0.096, P = 0.22). Comparing centers with higher than expected costs and allograft failure rates (lower performing) and centers with lower than expected costs and failure rates (higher-performing) showed differences in donor and recipient characteristics. As these characteristics were accounted for in the adjusted cost and allograft failure models, they are unlikely to explain the differences between higher- and lower-performing centers. CONCLUSIONS: Further investigations are needed to determine specific cost-effective practices of higher- and lower-performing centers to reduce costs and incidence of allograft failure.

Liver sharing and organ procurement organization performance.

Whether the liver allocation system shifts organs from better performing organ procurement organizations (OPOs) to poorer performing OPOs has been debated for many years. Models of OPO performance from the Scientific Registry of Transplant Recipients make it possible to study this question in a data-driven manner. We investigated whether each OPO's net liver import was correlated with 2 performance metrics [observed to expected (O:E) liver yield and liver donor conversion ratio] as well as 2 alternative explanations [eligible deaths and incident listings above a Model for End-Stage Liver Disease (MELD) score of 15]. We found no evidence to support the hypothesis that the allocation system transfers livers from better performing OPOs to centers with poorer performing OPOs. Also, having fewer eligible deaths was not associated with a net import. However, having more incident listings was strongly correlated with the net import, both before and after Share 35. Most importantly, the magnitude of the variation in OPO performance was much lower than the variation in demand: although the poorest performing OPOs differed from the best ones by less than 2-fold in the O:E liver yield, incident listings above a MELD score of 15 varied nearly 14-fold. Although it is imperative that all OPOs achieve the best possible results, the flow of livers is not explained by OPO performance metrics, and instead, it appears to be strongly related to differences in demand.

New national allocation policy for deceased donor kidneys in the United States and possible effect on patient outcomes.

In 2013, the Organ Procurement and Transplantation Network in the United States approved a new national deceased donor kidney allocation policy that introduces the kidney donor profile index (KDPI), which gives scores of 0%-100% based on 10 donor factors. Kidneys with lower KDPI scores are associated with better post-transplant survival. Important features of the new policy include first allocating kidneys from donors with a KDPI≤20% to candidates in the top 20th percentile of estimated post-transplant survival, adding waiting time from dialysis initiation, conferring priority points for a calculated panel-reactive antibody (CPRA)>19%, broader sharing of kidneys for candidates with a CPRA≥99%, broader sharing of kidneys from donors with a KDPI>85%, eliminating the payback system, and allocating blood type A2 and A2B kidneys to blood type B candidates. We simulated the distribution of kidneys under the new policy compared with the current allocation policy. The simulation showed increases in projected median allograft years of life with the new policy (9.07 years) compared with the current policy (8.82 years). With the new policy, candidates with a CPRA>20%, with blood type B, and aged 18-49 years were more likely to undergo transplant, but transplants declined in candidates aged 50-64 years (4.1% decline) and ≥65 years (2.7% decline). These simulations demonstrate that the new deceased donor kidney allocation policy may improve overall post-transplant survival and access for highly sensitized candidates, with minimal effects on access to transplant by race/ethnicity and declines in kidney allocation for candidates aged ≥50 years.

The role of procurement biopsies in acceptance decisions for kidneys retrieved for transplant.

BACKGROUND AND OBJECTIVES: There is a shortage of kidneys for transplant, and many patients on the deceased donor kidney transplant waiting list would likely benefit from kidneys that are currently being discarded. In the United States, the most common reason given for discarding kidneys retrieved for transplant is procurement biopsy results. This study aimed to compare biopsy results from discarded kidneys with discard attributed to biopsy findings, with biopsy results from comparable kidneys that were successfully transplanted. DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS: In this retrospective, observational, case-control study, biopsy reports were examined from 83 kidneys discarded in 2010 due to biopsy findings (cases), 83 contralateral transplanted kidneys from the same donor (contralateral controls), and 83 deceased donors randomly matched to cases by donor risk profile (randomly matched controls). A second procurement biopsy was obtained in 64 of 332 kidneys (19.3%). RESULTS: The quality of biopsy reports was low, with amounts of tubular atrophy, interstitial inflammation, arteriolar hyalinosis, and acute tubular necrosis often not indicated; 69% were wedge biopsies and 94% used frozen tissue. The correlation between first and second procurement biopsies was poor; only 25% of the variability (R(2)) in glomerulosclerosis was explained by biopsies being from the same kidney. The percentages of glomerulosclerosis overlapped substantially between cases, contralateral controls, and randomly matched controls: 17.1%±15.3%, 9.0%±6.6%, and 5.0%±5.9%, respectively. Of all biopsy findings, only glomerulosclerosis>20% was independently correlated with discard (cases versus contralateral controls; odds ratio, 15.09; 95% confidence interval, 2.47 to 92.41; P=0.003), suggesting that only this biopsy result was used in acceptance decisions. One-year graft survival was 79.5% and 90.7% in contralateral and randomly matched controls, respectively, versus 91.6% among all deceased donor transplants in the Scientific Registry of Transplant Recipients. CONCLUSIONS: Routine use of biopsies could lead to unnecessary kidney discards.

Metformin use in kidney transplant recipients in the United States: an observational study.

BACKGROUND/AIMS: Although metformin is contraindicated in patients with increased serum creatinine levels (≥1.5 mg/dl in men, ≥1.4 mg/dl in women) in the United States, its use has not been systematically examined in kidney transplant recipients. We aimed to determine the frequency of metformin use and its associations among kidney transplant recipients, and to assess allograft and patient survival associated with metformin use. METHODS: In this retrospective cohort study, we linked Scientific Registry of Transplant Recipients data for all incident kidney transplants 2001-2012 and national pharmacy claims (n = 46,914). We compared recipients having one or more pharmacy claims for a metformin-containing product (n = 4,609) and recipients having one or more claims for a non-metformin glucose-lowering agent (n = 42,305). RESULTS: On average, metformin claims were filled later after transplant and were associated with higher estimated glomerular filtration rates before the first claim. Median serum creatinine (mg/dl) levels before the first claim were lower in recipients with metformin claims than in those with non-metformin claims (1.3 [interquartile range 1.0-1.7] vs. 1.6 [1.2-2.5], respectively; p < 0.0001). Metformin was associated with lower adjusted hazards for living donor (0.55, 95% confidence interval 0.38-0.80; p = 0.002) and deceased donor (0.55, 0.44-0.70; p < 0.0001) allograft survival at 3 years posttransplant, and with lower mortality. CONCLUSIONS: Despite metformin being contraindicated in renal dysfunction, many kidney transplant recipients receive it, and it is not associated with worse patient or allograft survival.