An emerging population: kidney transplant candidates who are placed on the waiting list after liver, heart, and lung transplantation

BACKGROUND AND OBJECTIVES

ESRD has an adverse impact on patients who have had previous nonrenal solid-organ transplants (NRTxs; liver, heart, lung) and may be referred for a kidney transplant (KTx).

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

Using Scientific Registry of Transplant Recipients data for all KTx candidates who had NRTx and were listed between 1995 and 2008, incidence of NRTx listings were compared with trends in KTx without NRTX. The efficacy of kidney transplantation relative to dialysis was measured in time-dependent Cox models that incorporated candidates with the applicable previous organ transplant as a reference group.

RESULTS

Overall, 4904 NRTx candidates were listed during the study period, growing from <1% of candidates before 1995 to 3.3% in 2008. A total of 38% of NRTx candidates were listed preemptively versus 21% of other candidates. NRTx candidates had dramatically shorter half-lives (≤ 4 years) after listing compared with previous KTx recipients (9.2 years). KTx demonstrated a survival advantage for each type of NRTx candidate relative to maintenance dialysis. Listing for expanded-criteria donor kidneys averaged 47% and did not differ significantly by previous transplant category.

CONCLUSIONS

KTx candidates who are placed on the waiting list after NRTx constitute a significant and more rapidly growing cohort compared with the general KTx candidate population. NRTx candidates are frequently listed preemptively but have rapid decline once placed on the waiting list. Targeted use of expanded-criteria donor and living-donor transplants in the NRTx population may be particularly important given their high mortality on the waiting list.

Significant Alterations in Reported Clinical Practice Associated with Increased Oversight of Organ Transplant Center Performance

In the past several years, emphasis on quality metrics in the field of organ transplantation has increased significantly, largely because of the new conditions of participation issued by the Centers for Medicare and Medicaid Services. These regulations directly associate patients' outcomes and measured performance of centers with the distribution of public funding to institutions. Moreover, insurers and marketing ventures have used publicly available outcomes data from transplant centers for business decision making and advertisement purposes. We gave a 10-question survey to attendees of the Transplant Management Forum at the 2009 meeting of the United Network for Organ Sharing to ascertain how centers have responded to the increased oversight of performance. Of 63 responses, 55% indicated a low or near low performance rating at their center in the past 3 years. Respondents from low-performing centers were significantly more likely to indicate increased selection criteria for candidates (81% vs 38%, P= .001) and donors (77% vs 31%, P< .001) as well as alterations in clinical protocols (84% vs 52%, P=.007). Among respondents indicating lost insurance contracts (31%), these differences were also highly significant. Based on respondents' perceptions, outcomes of performance evaluations are associated with significant changes in clinical practice at transplant centers. The transplant community and policy makers should practice vigilance that performance evaluations and regulatory oversight do not inadvertently lead to diminished access to care among viable candidates or decreased transplant volume.

Metabolic syndrome and mild to moderate chronic kidney disease among minorities

The incidence and prevalence of metabolic syndrome and chronic kidney disease (CKD) are increasing in the US population as a whole, but much more rapidly among ethnic minorities. Recent studies have shown that metabolic syndrome is an independent risk factor for the development of incident CKD in African Americans and American Indians distinct from its impact on cardiovascular and all-cause mortality. The pathogenesis of metabolic syndrome in ethnic minorities often is multifactorial. We review the myriad facets of the impact of the metabolic syndrome on the pathophysiology of CKD in minorities. In addition to classic biochemical and physiologic factors, increasing attention is being drawn to the major role of novel factors such as adiponectin and socioeconomic and cultural factors in the development of obesity and insulin resistance; an understudied area that may modulate clinically relevant consequences of biochemical and pathophysiologic aberrations. We present an integrated pathophysiologic viewpoint that incorporates insights from basic science, socioeconomic inquiry, and clinical studies into a framework for clinical practice and investigation.

The elephant in the room: failings of current clinical endpoints in kidney transplantation

In this opinion piece, we address the limitations of the two most common clinical endpoints in kidney transplantation trials (acute rejection and renal function) and attempt to offer a reasonable framework by which to find true and reliable early endpoints that reflect long-term outcomes. Other potential endpoints tested in recent years, including the use of genomic and proteomic markers are still in development. Until other reliable endpoints are established, it is important to understand what can be inferred from ongoing studies that utilize these endpoints and what further information we need to derive 'true' surrogate endpoints. We consider evaluation of current markers using the 'Prentice criteria', which bases assessment of endpoints as true surrogates on four primary rules. Based on our assessment, progress in understanding the safety and efficacy of new therapies and interventions in kidney transplantation will remain limited with current makers. Prospectively, we advocate: (i) significant caution in extrapolating long-term outcomes from currently utilized clinical markers, (ii) use of traditional hard endpoints whenever feasible and (iii) dedication of efforts for more data collection on specific disease entities and greater diligence in determining the onset of deleterious processes.

Elevated incidence of posttransplant erythrocytosis after simultaneous pancreas kidney transplantation

Posttransplant erythrocytosis (PTE) poses a potential risk of thrombosis in kidney transplantation. Clinical observation of our systemically drained simultaneous kidney pancreas transplant (S-SPK) patients showed a higher incidence of PTE and need for phlebotomies. To evaluate the incidence of PTE we analyzed hematocrit (Hct) levels and frequency of phlebotomies in 94 SPK as compared to 174 living donor (LD) recipients and 53 type-I diabetic with kidney transplant only. For study purposes we defined PTE as Hct >50% or the necessity for phlebotomies. Kaplan-Meier plots and Cox proportional hazard models were used to examine the association between the transplant type and PTE. We found an increased incidence of PTE in SPK compared to LD (p < 0.001). In the multivariate model, SPK had a 5-fold risk for the development of PTE (AHR 5.3, 95% CI 1.8, 15.9). The incidence of therapeutic phlebotomy was 13% among SPK patients and 4% in LD kidney recipients; 19 patients altogether. A total of 64 units were phlebotomized (48-SPK and 16-LD). Type I diabetic patients with a kidney transplant showed a 0% incidence of PTE. We observed a greater incidence of PTE and phlebotomies in S-SPK compared to LD with kidney only transplant recipients.

The success of continued steroid avoidance after kidney transplantation in the US

There has been a significant increase in the use of steroid avoidance regimens as initial treatment for kidney transplant recipients. Early results of the effectiveness of this strategy has been mixed with certain prospective trials indicating increased acute rejection but population-based studies indicating similar or better graft survival as compared to steroid maintenance. We conducted a retrospective study of national registry data to evaluate risk factors for discontinuation of steroid avoidance protocols based on patient characteristics and concomitant immunosuppression. We evaluated 84 647 solitary kidney transplant recipients in the US with at least 6 months graft survival including 24 218 initially discharged without maintenance steroids. We utilized logistic models to assess risk factors for new initiation of steroids after initial steroid-avoidance and survival models to describe graft survival for patients after return to steroids. The most prominent risk factors for new initiation of steroids after deceased donor kidney transplantation included African-American race (AOR = 1.32, p < 0.01), retransplants (AOR = 1.81, p < 0.01), highly sensitized recipients (AOR = 1.29, p < 0.01), recipients with Medicaid (AOR = 1.85, p < 0.01), elevated HLA-MM (AOR = 1.26, p < 0.01) and older donor age (AOR = 1.19, p < 0.01). Concomitant medications were also significantly associated with the propensity to newly initiate steroids. Cumulatively the study suggests that both patient characteristics and concomitant medications are strongly associated with the success of steroid avoidance immunosuppressive regimens.

Single kidney transplantation from young pediatric donors in the United States

Kidney transplantation (KTX) from small pediatric donors is performed as single or en bloc. Criteria to determine when to split pediatric donor kidneys and transplant as singles are not well established. Data reported to the Scientific Registry of Transplant Recipient for donors <10 yrs from 1995 to 2007 were reviewed (n = 5079). Donors were categorized by weight group by 5 kg increments and solitary (n = 3503) versus en bloc (n = 1576). The primary outcome was overall graft survival. Results were compared as adjusted hazard ratios (aHR) relative to ideal standard criteria donors (SCDs) (defined as age 18-39 without other risk factors), non-ideal SCDs (all other SCDs) and expanded criteria donors (age 50-59 with other risk factors or age >or=60). Single KTX from donors >or= 35 kg conferred a similar risk of graft survival as ideal SCDs. Of donors 10-34 kg, risks of en bloc KTX were similar to ideal and risks of single KTX to non-ideal SCDs; single and en bloc KTXs had 7.9 and 5.2 graft losses per 100 follow-up years, respectively. Single KTX from donors >35 kg are similar to ideal SCDs. Single KTX from donors 10-35 kg are similar to non-ideal SCDs. From a resource perspective, pediatric donors 10-35 kg used as singles offer more cumulative graft years than when used en bloc.

AZA/tacrolimus is associated with similar outcomes as MMF/tacrolimus among renal transplant recipients

There have been several retrospective studies indicating benefits associated with mycophenalate mofetil (MMF) compared to azathioprine (AZA) for renal transplant recipients. However, these analyses evaluated outcomes prior to changes in utilization patterns of concomitant immunosuppression. Recent prospective trials have indicated similar outcomes among patients treated with MMF and AZA. The aim of this study was to evaluate outcomes in a broad group of patients in the more recent era. We evaluated adult solitary renal transplant recipients from 1998 to 2006 with the national SRTR database. Primary outcomes were time to patient death and graft loss, complications and renal function. Models were adjusted for potential confounding factors, propensity scores and stratified between higher/lower risk transplants and concomitant immunosuppression. Adjusted models indicated a modest risk among AZA patients for graft loss (AHR = 1.14, 95% CI 1.07-1.20); however, this was not apparent among AZA patients also treated with tacrolimus (AHR = 0.97, 95% CI 0.85-1.11]. One-year acute rejection rates were reduced for patients on MMF versus AZA (10 vs. 13%, p < 0.01); there were no statistically significant differences of malignancies, renal function or BK virus at 1 year. The primary findings suggest the association of MMF with improved outcomes may not be apparent in patients also receiving tacrolimus.

Uric acid levels have no significant effect on renal function in adult renal transplant recipients: evidence from the symphony study

BACKGROUND AND OBJECTIVES

Uric acid (UA) has been linked to renal damage in experimental models of kidney failure. In humans, no definitive link between UA and renal function has been established, but several epidemiologic studies have suggested that higher UA levels are associated with accelerated loss of renal function, higher incidence of dialysis, and death. Many of the associations have been limited by the colinearity between UA levels and renal function. Renal transplantation is no exception, and limited information is available concerning the independent role of UA on progression of renal function in transplant recipients.

DESIGN, SETTING, PARTICIPANTS, AND MEASUREMENTS

We investigated the association between UA and renal function progression during the first 3 yr after transplantation, adjusted for baseline renal function, in 1645 patients who were enrolled in the Symphony study.

RESULTS

When corrected for baseline renal function, UA levels 1 mo after transplantation were not associated with 3-yr renal function (P = 0.62). There was a strong colinearity between calculated renal function and UA levels 1 mo after transplantation. In fact, when not corrected for baseline renal function, there was a significant association between UA and renal function at 3 yr (P = 0.005).

CONCLUSIONS

Low renal function is associated with higher UA levels, but higher UA levels are not independently associated with progression of renal dysfunction after kidney transplantation.

Acute kidney injury is associated with increased long-term mortality after cardiothoracic surgery

BACKGROUND

Long-term survival after acute kidney injury (AKI) is poorly studied. We report the relationship between long-term mortality and AKI with small changes in serum creatinine during hospitalization after various cardiothoracic surgery procedures.

METHODS AND RESULTS

This was a retrospective study of 2973 patients with no history of chronic kidney disease who were discharged from the hospital after cardiothoracic surgery between 1992 and 2002. AKI was defined by the RIFLE classification (Risk, Injury, Failure, Loss, and End stage), which requires at least a 50% increase in serum creatinine and stratifies patients into 3 grades of AKI: Risk, injury, and failure. Patient survival was determined through the National Social Security Death Index. Long-term survival was analyzed with a risk-adjusted Cox proportional hazards regression model. Survival was worse among patients with AKI and was proportional to its severity, with an adjusted hazard ratio of 1.23 (95% CI 1.06 to 1.42) for the least severe RIFLE risk class and 2.14 (95% CI 1.73 to 2.66) for the RIFLE failure class compared with patients without AKI. Survival was worse among all subgroups of cardiothoracic surgery with AKI except for valve surgery. Patients with complete renal recovery after AKI still had an increased adjusted hazard ratio for death of 1.28 (95% CI 1.11 to 1.48) compared with patients without AKI.

CONCLUSIONS

The risk of death associated with AKI after cardiothoracic surgery remains high for 10 years regardless of other risk factors, even for those patients with complete renal recovery. Improved renal protection and closer postdischarge follow-up of renal function may be warranted.

Treatment for BK virus: incidence, risk factors and outcomes for kidney transplant recipients in the United States

There has been a notable rise of BK virus among kidney transplant recipients. Single-center reports have identified risk factors for development of BK virus. However, there has not been an assessment of risk factors and incidence of this complication at a national level. This study utilized newly collected follow-up information from the national SRTR database to investigate incidence, risk factors and outcomes for solitary kidney transplant recipients associated with treatment for BK virus (TBKV) from 2004 to 2006. Logistic and Cox models were utilized to assess risk factors and evaluate graft survival associated with TBKV. Incidence of TBKV was 1.6% at 6 months and 2.6% at 1 year following transplantation. Patients with and without TBKV at 6 months had 79% and 90% 3-year overall graft survival respectively. Risk factors included advanced donor age, pediatric, African American and male recipients, human leukocyte antigen-mismatching and tacrolimus and thymoglobulin induction as baseline immunosuppression. Acute rejection episodes were more frequent prior to and following TBKV. TBKV is a common and rising incidence, varies based on transplant characteristics and should be included as a safety endpoint in studies investigating immunosuppressive protocols. Careful monitoring and further understanding of disease etiology and treatment strategies are needed.

Outcomes and utilization of kidneys from deceased donors with acute kidney injury

Utilization and long-term outcomes of kidneys from donors with elevated terminal serum creatinine (sCr) levels have not been reported. Using data from the Scientific Registry of Transplant Recipients from 1995 to 2007, recipient outcomes of kidneys from adult donors were evaluated stratified by standard criteria (SCD; n = 82 262) and expanded criteria (ECD; n = 16 978) donor type and by sCr </=1.5, 1.6-2.0 and >2.0 mg/dL. Discard rates for SCDs were ascertained. The relative risk of graft loss was similar for recipients of SCD kidneys with sCr of 1.6-2.0 and >2.0 mg/dL, compared to </=1.5 mg/dL. For ECD recipients, the relative risk of graft failure significantly increased with increasing sCr. Of potential SCDs, the adjusted risk of discard was higher with sCr >2.0 mg/dL (adjusted odds ratio [AOR] 7.04, 95% confidence interval [CI] 6.5-7.6) and 1.6-2.0 mg/dL (AOR 2.7; CI 2.5-2.9) relative to sCr </=1.5 mg/dL. Among potential SCDs, elevated terminal creatinine is a strong independent risk factor for kidney discard; yet, when kidney transplantation is performed elevated donor terminal creatinine is not a risk factor for graft loss. Further research is needed to identify safe practices for the optimal utilization of SCD kidneys from donors with acute kidney injury.

Recovery factors affecting utilization of small pediatric donor kidneys

Kidneys from small pediatric donors are underutilized. Using data from the Scientific Registry of Transplant Recipients for donors <21 kg in which at least one organ was recovered from 1997 to 2007 (n = 3341), donor and recovery factors were evaluated by multivariate analysis for associations with (a) kidney nonrecovery and (b) transplantation of recovered kidneys.

RESULTS

The proportion of kidney recoveries were 55% during liver procurements and 40% during intestine procurements amongst donors <10 kg (p < 0.01) compared to 93% and 88%, respectively, for donors weighing 10-20 kg (p = 0.003). Intestine procurement was independently associated with an 81% greater likelihood of kidney nonrecovery (p < 0.0001) and a 48% lower likelihood of transplantation (p = 0.0004). A multivariate Cox model indicated that single kidney recipients had a 63% higher risk of graft failure compared with en bloc kidney recipients (p < 0.0001); however, concurrent intestine recovery was not a significant risk factor for graft loss. Intestine recovery from donors <21 kg of age is strongly associated with higher kidney nonrecovery and lower transplantation rates. Graft survival is worse with single kidney transplantation, but is not significantly affected by intestine recovery. Small pediatric donors procurement teams should strive to increase kidney recoveries overall and en bloc recoveries in particular.

Uric acid: a novel risk factor for acute kidney injury in high-risk cardiac surgery patients?

BACKGROUND

Uric acid has been reported to be a risk factor for the development of chronic kidney disease; however, no study has examined whether uric acid may confer a risk for acute kidney injury.

METHODS

We investigated the relation between serum uric acid and the incidence of postoperative acute kidney injury in patients undergoing high-risk cardiovascular surgery (cardiac valve and aneurysm surgery).

RESULTS

Following cardiovascular surgery, 18 of 58 patients (31%) developed acute kidney injury, with 11 of 24 (45.8%) in the elevated uric acid group (defined as >6 mg/dl) and 7 of 34 (20.5%) in the normal uric acid group (p = 0.05). After controlling for baseline renal function, left ventricular ejection fraction, use of nesiritide, type of surgery, and history of previous surgery, an elevated preoperative uric acid conferred a 4-fold risk for acute kidney injury (OR: 3.98, CI: 1.10-14.33, p = 0.035) and longer hospital stay (36.35 vs. 24.66 days, p = 0.009).

CONCLUSION

This preliminary study suggests that uric acid may be a novel risk factor for acute kidney injury in patients undergoing high-risk cardiovascular surgery.

The relationship between circulating natural killer cells after reduced intensity conditioning hematopoietic stem cell transplantation and relapse-free survival and graft-versus-host disease

BACKGROUND

Natural killer cells are known to have anti-tumor activity in haploidentical hematopoietic stem cell transplantation. We hypothesized that reconstituted circulating natural killer cells may be associated with improved relapse-free survival after HLA-matched hematopoietic stem cell transplantation.

DESIGN AND METHODS

Serial peripheral blood absolute natural killer cell counts were prospectively measured by flow cytometry of lymphocytes expressing CD56 and CD16 in 167 patients. Cluster analysis was used at engraftment and 60 days post-transplant to distinguish patients with high and low absolute natural killer cell counts. At engraftment 80 patients had high counts (> 22.2/mm3) and 43 had low counts. At 60 days post-transplant 84 patients had high counts (> 18.2/mm3) and 38 had low counts. The primary study end-points were death, relapse and acute graft-versus-host disease. The median follow-up was 373 days (range, 67-1767).

RESULTS

Among patients given reduced intensity conditioning, a low absolute natural killer cell count at 60 days post-transplant was independently associated with relapse [adjusted hazard ratio (AHR) = 28.4, 95% confidence interval (CI) 4.3-186.4] and death (AHR = 17.5, 95% CI 4.3-71.3). Furthermore, patients given reduced intensity conditioning who had a high absolute natural killer cell count at 60 days had a significantly better 1-year survival than those with a low count by Kaplan-Meier analysis (83% vs. 11%, p<0.001). Multivariate analysis confirmed that low 60-day absolute natural killer count in patients given reduced intensity conditioning was independently associated with an increase in relapse or death (AHR = 20.22, 95% CI 4.76-85.40). In contrast, there was no significant association between 60-day absolute natural killer cell counts and clinical outcomes in patients receiving myeloablative conditioning. There was no significant association between absolute natural killer cell count and graft-versus-host disease.

CONCLUSIONS

High natural killer cell reconstitution is associated with reduced relapse and death without an increased incidence of graft-versus-host-disease after reduced intensity conditioning allogeneic hematopoietic stem cell transplantation. Measuring reconstituted natural killer cells expressing CD56(+)/CD16(+) post-transplant may have novel prognostic and therapeutic implications.

Design and analysis of clinical trials in transplantation: principles and pitfalls

The contributions of prospective randomized controlled trials (RCTs) to the advancement of solid organ transplantation are well appreciated. However, some misconception exists that results deriving from RCTs uniformly provide clinically relevant, definitive and generalized evidence. While there is little doubt that RCTs are the gold standard to test cause-and-effect relationships, the quality and subsequent utility of trials carried out in this field vary substantially. As with all other disciplines, our ability to interpret and implement the findings of RCTs into practice is strongly dependent on the study design and statistical rigor of the analysis. Failure to conduct trials with appropriate standards or interpret trials with the appropriate limitations may place patients at risk or waste valuable healthcare resources. The purpose of this review is to delineate important principles of study design and analysis of RCTs that are commonly overlooked. This review will discuss possible limitations of trials with specific applications in the field of transplantation. Progress in the field of transplantation is highly dependent on critical examination of existing clinical trials and vigilance regarding the optimal development of future trials.

Evaluation criteria for report cards of healthcare providers

Report cards, performance evaluations, and quality assessments continue to penetrate the lexicon of the healthcare sector. The value of report cards is typically couched as enhancing consumerism among patients, increasing accountability among healthcare providers, and more broadly increasing the transparency of healthcare information. This paper discusses the potential benefits and pitfalls of these performance assessments. This paper briefly reviews empirical evidence regarding the impact of report cards for healthcare providers and synthesizes the role and limitations of these performance measures into distinct evaluation criteria. The rapid proliferation of report cards for healthcare providers suggests a growing need to develop mechanisms and tools to evaluate their impact. The risks associated with utilizing report cards for provider oversight include the deleterious impact on vulnerable populations and a failure to accurately measure quality of care. The capacity to create report cards should not be the sole criterion to develop and utilize report cards to evaluate healthcare providers. Rather, careful consideration of the benefits and risks should accompany the implementation and utilization of report cards into regulatory processes. This report proposes an evaluation checklist by which to assess the role of report cards in a given healthcare context.

The overlapping risk profile between dialysis patients listed and not listed for renal transplantation

The survival advantage of kidney transplantation extends to many high-risk ESRD patients; however, numerous factors ultimately determine which patients are evaluated and listed for the procedure. Broad goals of patient evaluation comprise identifying patients who will benefit from transplantation and excluding patients who might be placed at risk. There is limited data detailing whether current access limitations and screening strategies have achieved the goal of listing the most appropriate patients. The study estimated the life expectancy of adult patients in the United States prior to transplantation with ESRD onset from 1995 to 2003. Factors associated with transplant listing were examined based on patient prognosis after ESRD. Approximately one-third of patients listed for transplantation within 1 year of ESRD had </=5-year life expectancy on dialysis. In contrast, one-third of patients not listed had >5-year life expectancy. The number of patients not listed with 'good' prognosis was significantly higher than those listed with 'poor' prognosis (134 382 vs. 16 807, respectively). Age, race, gender, insurance coverage and body mass index (BMI) were associated with likelihood for listing with 'poor' prognosis and not listing with 'good' prognosis. Over the past decade, many ESRD patients viable for transplantation have not listed for transplantation while higher-risk patients have listed rapidly.

Value of posttransplant antibody tests in the evaluation of patients with renal graft dysfunction

Posttransplant HLA antibodies correlate with C4d positive rejection and decreased graft survival. However, the diagnostic value of various antibody tests in the management of patients presenting with graft dysfunction is uncertain. Whether all or some patients should be tested, how often, what antibodies to test for and how to interpret results in presensitized or transfused patients, are issues still unresolved. We tested for HLA and non-HLA antibodies by flow cytometry assays in 103 consecutive patients with graft dysfunction. The results show that: (1) C4d positive rejection was diagnosed in 75% of patients who developed posttransplant HLA antibodies, but only in 2% in antibody negative patients. (2) The correlation existed for donor specific IgG antibodies but not for IgM or nondonor specific IgG antibodies. (3) Weak antibody reactivity required confirmation by alternative testing as there were false positive results. (4) Posttransplant transfusions did not induce de novo HLA antibodies. (5) Negative antibody results were unlikely to turn positive after several months of follow-up. (6) Antibodies to the angiotensin II type 1 receptor, HLA-DP and MICA did not correlate with C4d+ rejection. We conclude that testing for posttransplant HLA antibodies is critical in narrowing the diagnostic alternatives in patients with graft dysfunction.