Performance of estimated glomerular filtration rate equations in Black living kidney donor candidates

INTRODUCTION

New estimated glomerular filtration rate (eGFR) equations using serum creatinine and/or cystatin C have been derived to eliminate adjustment by perceived Black ancestry. We sought to analyze the performance of newer eGFR equations among Black living kidney donor candidates.

METHODS

Black candidates (n = 64) who had measured iothalamate GFR between January 2015 and October 2021 were included, and eGFR was calculated using race adjusted (eGFRcr2009 and eGFRcr-cys2012) and race unadjusted (eGFRcys2012, eGFRcr2021, and eGFRcr-cys2021) CKD-EPI equations. Bias and accuracy were calculated.

RESULTS

The eGFRcr2021 equation had a negative bias of 9 mL/min/1.73 m2 , while other equations showed a modest positive bias. Accuracy within 10% and 30% was greatest using the eGFRcr-cys2021 equation. With the eGFRcr2021 equation, 9.4% of donors with an mGFR > 80 mL/min/1.73 m2 were misclassified as having an eGFR < 80 mL/min/1.73 m2 . eGFR was also compared among 18 kidney donors at 6-24 months post-donation. Post-donation, the percentage of donors with an eGFR < 60 mL/min/1.73 m2 was 44% using the eGFRcr2021 equation compared to 11% using the eGFRcr-cys2021 equation.

CONCLUSION

The CKD-EPICr2021 equation appears to underestimate true GFR in Black living donor candidates. Alternatively, compared to CKD-EPICr2021, the CKD-EPICr-CysC2021 equation appears to perform with less bias and improved accuracy.

The Number and Size of Individual Kidney Medullary Pyramids is Associated with Clinical Characteristics, Kidney Biopsy Findings, and CKD Outcomes among Kidney Donors

SIGNIFICANCE STATEMENT

Segmentation of multiple structures in cross-sectional imaging is time-consuming and impractical to perform manually, especially if the end goal is clinical implementation. In this study, we developed, validated, and demonstrated the capability of a deep learning algorithm to segment individual medullary pyramids in a rapid, accurate, and reproducible manner. The results demonstrate that cortex volume, medullary volume, number of pyramids, and mean pyramid volume is associated with patient clinical characteristics and microstructural findings and provide insights into the mechanisms that may lead to CKD.

BACKGROUND

The kidney is a lobulated organ, but little is known regarding the clinical importance of the number and size of individual kidney lobes.

METHODS

After applying a previously validated algorithm to segment the cortex and medulla, a deep-learning algorithm was developed and validated to segment and count individual medullary pyramids on contrast-enhanced computed tomography images of living kidney donors before donation. The association of cortex volume, medullary volume, number of pyramids, and mean pyramid volume with concurrent clinical characteristics (kidney function and CKD risk factors), kidney biopsy morphology (nephron number, glomerular volume, and nephrosclerosis), and short- and long-term GFR <60 or <45 ml/min per 1.73 m 2 was assessed.

RESULTS

Among 2876 living kidney donors, 1132 had short-term follow-up at a median of 3.8 months and 638 had long-term follow-up at a median of 10.0 years. Larger cortex volume was associated with younger age, male sex, larger body size, higher GFR, albuminuria, more nephrons, larger glomeruli, less nephrosclerosis, and lower risk of low GFR at follow-up. Larger pyramids were associated with older age, female sex, larger body size, higher GFR, more nephrons, larger glomerular volume, more nephrosclerosis, and higher risk of low GFR at follow-up. More pyramids were associated with younger age, male sex, greater height, no hypertension, higher GFR, lower uric acid, more nephrons, less nephrosclerosis, and a lower risk of low GFR at follow-up.

CONCLUSIONS

Cortex volume and medullary pyramid volume and count reflect underlying variation in nephron number and nephron size as well as merging of pyramids because of age-related nephrosclerosis, with loss of detectable cortical columns separating pyramids.

Self-reported marijuana use and its effects on overall approval in potential living kidney donors

BACKGROUND

Past and present substance use is an important part of the psychosocial evaluation of potential living kidney donors (LKDs). Increasing state legalizations and social acceptance of marijuana (MJ) use can create challenges for transplant centers.

METHODS

We investigated the frequency of reporting MJ use, and its effect on the LKD evaluation. A retrospective chart review was performed on all living donor candidates from December 2016 to December 2019 for reports of MJ use, both on an electronic intake form and during clinic evaluation with a licensed social worker (SW).Active MJ use was defined as current use or use within one year of evaluation. Baseline characteristics between MJ users and non-users were compared at each step of donor evaluation. We explored variables associated with MJ use including additional consults and testing during the donor evaluation. Overall approval and donation rates for living donors with active MJ use were compared to non-users. Additionally, 1-year donor follow up was compared between the two groups. Results Of 1,818 living donor candidates who completed the intake form, 132 admitted to active MJ use. Compared to non-users, MJ users were more likely to be younger, male, single, renting a home, and with a lower level of education. 33 of 338 candidates who completed a social work evaluation reported MJ use. Compared to non-users, MJ users were more frequently classified as moderate or high risk on SW evaluation, and often required a toxicology screen or psychiatry visit for clearance to donate. 24.2% of MJ users vs 9.5% of non-users discontinued their evaluation (P<0.01). 42.4% of MJ users vs 56.1% of non-users donated their kidney (P = 0.13). For those who donated, MJ users were less likely than non-users to follow up at 1 year (57.1% vs 83.0, p-value 0.02).

CONCLUSION

MJ users were often asked to complete additional steps in their evaluation before an approval decision was made, which may have led to the higher rate of donor drop out observed in this group. Further research is needed to assess the effects of MJ use on living donor candidacy, as well as any effects of MJ use on long-term donor outcomes. This article is protected by copyright. All rights reserved.

Donor-Derived Renal Cell Carcinoma in a Kidney Allograft: A Case Report

Renal cell carcinoma (RCC) in the kidney allograft is a relatively rare complication most commonly seen approximately a decade or more after transplant. We report a case of diffuse multifocal RCC within 6 months of transplant. The initial signal leading to an abnormality in the graft was an elevated routine cell-free DNA. Initial imaging findings appeared consistent with post-transplant lymphoproliferative disorder; however, biopsy would ultimately yield RCC. The patient's diffuse disease necessitated radical nephrectomy. Tumor DNA fingerprinting was employed in this case to show the tumor originated from donor tissue rather than host, indicating primary rather than metastatic disease. Early RCC is a rare complication. Most cases are detected at an early stage, likely as a result of increased surveillance with ultrasound imaging. A donor's social history including significant tobacco use should be considered when evaluating the risk of malignancy transmission in the allograft. Clinicians should be aware of multifocal RCC as a potential differential diagnosis for diffuse nodular infiltrates in the allograft.

Beyond the Biopsy: Monitoring Immune Status in Kidney Recipients

Improved long-term kidney allograft survival is largely related to better outcomes at 12 months, in association with declining acute rejection rates and more efficacious immunosuppression. Finding the right balance between under- and overimmunosuppression or rejection versus immunosuppression toxicity remains one of transplant's holy grails. In the absence of precise measures of immunosuppression burden, transplant clinicians rely on nonspecific, noninvasive tests and kidney allograft biopsy generally performed for cause. This review appraises recent advances of conventional monitoring strategies and critically examines the plethora of emerging tests utilizing tissue, urine, and blood samples to improve upon the diagnostic precision of allograft surveillance.

Long-term kidney transplant graft survival-Making progress when most needed

Current short-term kidney post-transplant survival rates are excellent, but longer-term outcomes have historically been unchanged. This study used data from the national Scientific Registry of Transplant Recipients (SRTR) and evaluated 1-year and 5-year graft survival and half-lives for kidney transplant recipients in the US. All adult (≥18 years) solitary kidney transplants (n = 331,216) from 1995 to 2017 were included in the analysis. Mean age was 49.4 years (SD +/-13.7), 60% male, and 25% Black. The overall (deceased and living donor) adjusted hazard of graft failure steadily decreased from 0.89 (95%CI: 0.88, 0.91) in era 2000-2004 to 0.46 (95%CI: 0.45, 0.47) for era 2014-2017 (1995-1999 as reference). Improvements in adjusted hazards of graft failure were more favorable for Blacks, diabetics and older recipients. Median survival for deceased donor transplants increased from 8.2 years in era 1995-1999 to an estimated 11.7 years in the most recent era. Living kidney donor transplant median survival increased from 12.1 years in 1995-1999 to an estimated 19.2 years for transplants in 2014-2017. In conclusion, these data show continuous improvement in long-term outcomes with more notable improvement among higher-risk subgroups, suggesting a narrowing in the gap for those disadvantaged after transplantation.

Failure to Advance Access to Kidney Transplantation over Two Decades in the United States

BACKGROUND

Extensive research and policies have been developed to improve access to kidney transplantation among patients with ESKD. Despite this, wide variation in transplant referral rates exists between dialysis facilities.

METHODS

To evaluate the longitudinal pattern of access to kidney transplantation over the past two decades, we conducted a retrospective cohort study of adult patients with ESKD initiating ESKD or placed on a transplant waiting list from 1997 to 2016 in the United States Renal Data System. We used cumulative incidence models accounting for competing risks and multivariable Cox models to evaluate time to waiting list placement or transplantation (WLT) from ESKD onset.

RESULTS

Among the study population of 1,309,998 adult patients, cumulative 4-year WLT was 29.7%, which was unchanged over five eras. Preemptive WLT (prior to dialysis) increased by era (5.2% in 1997-2000 to 9.8% in 2013-2016), as did 4-year WLT incidence among patients aged 60-70 (13.4% in 1997-2000 to 19.8% in 2013-2016). Four-year WLT incidence diminished among patients aged 18-39 (55.8%-48.8%). Incidence of WLT was substantially lower among patients in lower-income communities, with no improvement over time. Likelihood of WLT after dialysis significantly declined over time (adjusted hazard ratio, 0.80; 95% confidence interval, 0.79 to 0.82) in 2013-2016 relative to 1997-2000.

CONCLUSIONS

Despite wide recognition, policy reforms, and extensive research, rates of WLT following ESKD onset did not seem to improve in more than two decades and were consistently reduced among vulnerable populations. Improving access to transplantation may require more substantial interventions.

Effects of body mass index on kidney transplant outcomes are significantly modified by patient characteristics

Body mass index (BMI) is a known risk factor associated with kidney transplant outcomes and is incorporated for determining transplant candidate eligibility. However, BMI is a coarse health measure and risks associated with BMI may vary by patient characteristics. We evaluated 296 807 adult (age > 17) solitary kidney transplant recipients from the Scientific Registry of Transplant Recipients (2000-2019). We examined effects of BMI using survival models and tested interactions with recipient characteristics. Overall, BMI demonstrated a "J-Shaped" risk profile with elevated risks for overall graft loss with low BMI and obesity. However, multivariable models indicated interactions between BMI with recipient age, diagnosis, gender, and race/ethnicity. Low BMI was relatively higher risk for older recipients (>60 years), people with type I diabetes, and males and demonstrated no additional risk among younger (18-39) and Hispanic recipients. High BMI was associated with elevated risk for Caucasians and attenuated risk among African Americans and people with type II diabetes. Effects of BMI had variable risks for mortality vs graft loss by recipient characteristics in competing risks models. The association of BMI with posttransplant outcomes is highly variable among kidney transplant recipients. Results are important considerations for personalized care and risk stratification. Findings suggest that transplant contraindications should not be based on absolute BMI thresholds but modified based on patient characteristics.

Comparison of high glomerular filtration rate thresholds for identifying hyperfiltration

BACKGROUND

High glomerular filtration rate (GFR) is often used as a surrogate for single-nephron hyperfiltration. Our objective was to determine the definition for high GFR that best reflects clinical and structural characteristics of hyperfiltration.

METHODS

We studied living kidney donors at the Mayo Clinic and Cleveland Clinic. Potential donors underwent evaluations that included measured GFR (mGFR) by iothalamate clearance and estimated GFR (eGFR) by the serum creatinine-based Chronic Kidney Disease-Epidemiology collaboration (CKD-EPI) equation. High GFR was defined by the 95th percentile for each method (mGFR or eGFR) using either overall or age-specific thresholds. High mGFR was defined as both corrected and uncorrected for body surface area. The association of high GFR by each definition with clinical characteristics and radiologic findings (kidney volume) was assessed. In the subset that donated, the association of high GFR with kidney biopsy findings (nephron number and glomerular volume) and single-nephron GFR was assessed.

RESULTS

We studied 3317 potential donors, including 2125 actual donors. The overall 95th percentile for corrected mGFR was 134 mL/min/1.73 m2 and for eGFR was 118 mL/min/1.73 m2. The age-based threshold for uncorrected mGFR was 198 mL/min - 0.943×Age, for corrected mGFR it was 164 mL/min/1.73 m2 - 0.730×Age and for eGFR it was 146 mL/min/1.73 m2 - 0.813×Age. High age-based uncorrected mGFR had the strongest associations with higher single-nephron GFR, larger glomerular volume, larger kidney volume, male gender, higher body mass index and higher 24-h urine albumin, but also had the strongest association with high nephron number. A high age-height-gender-based uncorrected mGFR definition performed almost as well but had a weaker association with nephron number and did not associate with male gender.

CONCLUSIONS

High age-based uncorrected mGFR showed the most consistent associations reflective of hyperfiltration. However, high age-based uncorrected mGFR has limited clinical utility because it does not distinguish between hyperfiltration and high nephron number.

Modest rates and wide variation in timely access to repeat kidney transplantation in the United States

Success of transplantation is not limited to initial receipt of a donor organ. Many kidney transplant recipients experience graft loss following initial transplantation and the benefits of expedited placement on the waiting list and retransplantation extend to this population. Factors associated with access to repeat transplantation may be unique given experience with the transplant process and prior viability as a candidate. We examined the incidence, risk factors, secular changes, and center-level variation of preemptive relisting or transplantation (PRLT) for kidney transplant recipients in the United States with graft failure (not due to death) using Scientific Registry of Transplant Recipients data from 2007 to 2018 (n = 39 557). Overall incidence of PRLT was 15% and rates of relisting declined over time. Significantly lower PRLT was evident among patients who were African American and Hispanic, males, older, obese, publicly insured, had lower educational attainment, were diabetic, had longer dialysis time prior to initial transplant, shorter graft survival, longer distance to transplant center, and resided in distressed communities. There was significant variation in PRLT by center, median = 13%, 10th percentile = 6%, 90th percentile = 24%. Cumulatively, results indicate that despite prior access to transplantation, incidence of PRLT is modest with pronounced clinical, social, and center-level sources of variation suggesting opportunities to improve preemptive care among patients with failing grafts.

Kidney Structural Features from Living Donors Predict Graft Failure in the Recipient

BACKGROUND

Nephrosclerosis, nephron size, and nephron number vary among kidneys transplanted from living donors. However, whether these structural features predict kidney transplant recipient outcomes is unclear.

METHODS

Our study used computed tomography (CT) and implantation biopsy to investigate donated kidney features as predictors of death-censored graft failure at three transplant centers participating in the Aging Kidney Anatomy study. We used global glomerulosclerosis, interstitial fibrosis/tubular atrophy, artery luminal stenosis, and arteriolar hyalinosis to measure nephrosclerosis; mean glomerular volume, cortex volume per glomerulus, and mean cross-sectional tubular area to measure nephron size; and calculations from CT cortical volume and glomerular density on biopsy to assess nephron number. We also determined the death-censored risk of graft failure with each structural feature after adjusting for the predictive clinical characteristics of donor and recipient.

RESULTS

The analysis involved 2293 donor-recipient pairs. Mean recipient follow-up was 6.3 years, during which 287 death-censored graft failures and 424 deaths occurred. Factors that predicted death-censored graft failure independent of both donor and recipient clinical characteristics included interstitial fibrosis/tubular atrophy, larger cortical nephron size (but not nephron number), and smaller medullary volume. In a subset with 12 biopsy section slides, arteriolar hyalinosis also predicted death-censored graft failure.

CONCLUSIONS

Subclinical nephrosclerosis, larger cortical nephron size, and smaller medullary volume in healthy donors modestly predict death-censored graft failure in the recipient, independent of donor or recipient clinical characteristics. These findings provide insights into a graft's "intrinsic quality" at the time of donation, and further support the use of intraoperative biopsies to identify kidney grafts that are at higher risk for failure.

Diagnostic Performance of Blood Pressure Measurement Modalities in Living Kidney Donor Candidates

BACKGROUND AND OBJECTIVES

Precise BP measurement to exclude hypertension is critical in evaluating potential living kidney donors. Ambulatory BP monitoring is considered the gold standard method for diagnosing hypertension, but it is cumbersome to perform. We sought to determine whether lower BP cutoffs using office and automated BP would reduce the rate of missed hypertension in potential living donors.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

We measured BP in 578 prospective donors using three modalities: (1) single office BP, (2) office automated BP (average of five consecutive automated readings separated by 1 minute), and (3) ambulatory BP. Daytime ambulatory BP was considered the gold standard for diagnosing hypertension. We assessed both the Seventh Report of the Joint National Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure (JNC-7) and the American College of Cardiology/American Heart Association (ACC/AHA) definitions of hypertension in the cohort. Empirical thresholds of office BP and automated BP for the detection of ambulatory BP-diagnosed hypertension were derived using Youden index, which maximizes the sum of sensitivity and specificity and gives equal weight to false positive and false negative values.

RESULTS

Hypertension was diagnosed in 90 (16%) prospective donors by JNC-7 criteria and 198 (34%) prospective donors by ACC/AHA criteria. Masked hypertension was found in 3% of the total cohort by JNC-7 using the combination of office or automated BP, and it was seen in 24% by ACC/AHA guidelines. Using Youden index, cutoffs were derived for both office and automated BP using JNC-7 (<123/82 and <120/78 mm Hg) and ACC/AHA (<119/79 and <116/76 mm Hg) definitions. Using these lower cutoffs, the sensitivity for detecting hypertension improved from 79% to 87% for JNC-7 and from 32% to 87% by ACC/AHA definition, with negative predictive values of 95% and 87%, respectively. Missed (masked) hypertension was reduced to 2% and 4% of the entire cohort by JNC-7and ACC/AHA, respectively.

CONCLUSIONS

The prevalence of hypertension was higher in living donor candidates using ACC/AHA compared JNC-7 definitions. Lower BP cutoffs in the clinic improved sensitivity and led to a low overall prevalence of missed hypertension in prospective living kidney donors.

Dramatic secular changes in prognosis for kidney transplant candidates in the United States

Over recent decades, numerous clinical advances and policy changes have affected outcomes for candidates of kidney transplantation in the United States. We examined the national Scientific Registry for Transplant Recipients for adult (18+) solitary kidney transplant candidates placed on the waiting list for primary listing from 2001 to 2015. We evaluated rates of mortality, transplantation, and waitlist removal. Among 340 115 candidates there were significant declines in mortality (52 deaths/1000 patient years in 2001-04 vs 38 deaths/1000 patient years in 2012-15) and transplant rates (304 transplants/1000 patient years in 2001-04 vs 212 transplants/1000 patient years in 2012-15) and increases in waitlist removals (15 removals/1000 patient years in 2001-04 vs 25/1000 patient years in 2012-15) within the first year after listing. At 5 years an estimated 37% of candidates listed in 2012-15 were alive without transplant as compared to 22% in 2001-04. Declines in mortality over time were significantly more pronounced among African Americans, candidates with longer dialysis duration, and those with diabetes (P < .001). Cumulatively, results indicate dramatic changes in prognoses for adult kidney transplant candidates, likely impacted by selection criteria, donor availability, regulatory oversight, and clinical care. These trends are important considerations for prospective policy development and research, clinical and patient decision-making, and evaluating the impact on access to care.

Significantly Lower Rates of Kidney Transplantation among Candidates Listed with the Veterans Administration: A National and Local Comparison

BACKGROUND

The process for evaluating kidney transplant candidates and applicable centers is distinct for patients with Veterans Administration (VA) coverage. We compared transplant rates between candidates on the kidney waiting list with VA coverage and those with other primary insurance.

METHODS

Using the Scientific Registry of Transplant Recipients database, we obtained data for all adult patients in the United States listed for a primary solitary kidney transplant between January 2004 and August 2016. Of 302,457 patients analyzed, 3663 had VA primary insurance coverage.

RESULTS

VA patients had a much greater median distance to their transplant center than those with other insurance had (282 versus 22 miles). In an adjusted Cox model, compared with private pay and Medicare patients, VA patients had a hazard ratio (95% confidence interval) for time to transplant of 0.72 (0.68 to 0.76) and 0.85 (0.81 to 0.90), respectively, and lower rates for living and deceased donor transplants. In a model comparing VA transplant rates with rates from four local non-VA competing centers in the same donor service areas, lower transplant rates for VA patients than for privately insured patients persisted (hazard ratio, 0.72; 95% confidence interval, 0.65 to 0.79) despite similar adjusted mortality rates. Transplant rates for VA patients were similar to those of Medicare patients locally, although Medicare patients were more likely to die or be delisted after waitlist placement.

CONCLUSIONS

After successful listing, VA kidney transplant candidates appear to have persistent barriers to transplant. Further contemporary analyses are needed to account for variables that contribute to such differential transplant rates.

Racial disparity in kidney transplant survival relates to late rejection and is independent of steroid withdrawal

Black kidney transplant recipients have more acute rejection (AR) and inferior graft survival. We sought to determine whether early steroid withdrawal (ESW) had an impact on AR and death-censored graft loss (DCGL) in blacks. From 2006 to 2012, AR and graft survival were analyzed in 483 kidney recipients (208 black and 275 non-black). Rates of ESW were similar between blacks (65%) and non-blacks (67%). AR was defined as early (≤3 months) or late (>3 months). The impact of black race, early AR, and late AR on death-censored graft failure was analyzed using univariate and multivariate Cox models. Blacks had greater dialysis vintage, more deceased donor transplants, and less HLA matching, yet rates of early AR were comparable between blacks and non-blacks. However, black race was a risk factor for late AR (HR: 3.48 (95% CI: 1.87-6.47)) Blacks had a greater rate of DCGL, partially driven by late AR (HR with late AR: 5.6; 95% CI: 3.3-9.3). ESW had no significant interaction with black race for risk of early AR, late AR, or DCGL. Independent of ESW, black kidney recipients had a higher rate of late AR after kidney transplantation. Late AR was highly predictive of DCGL and contributed to inferior graft survival in blacks.

Clinical and Pathology Findings Associate Consistently with Larger Glomerular Volume

Background Glomerular volume increases when demand exceeds nephron supply, which may lead to glomerulosclerosis. It is unclear if determinants of glomerular volume are consistent between populations that differ by severity of comorbidities.Methods We studied kidney biopsy specimens from living kidney donors (n=2453) and patients who underwent radical nephrectomy for a renal tumor (n=780). We scanned specimen sections into high-resolution digital images, manually traced glomerular profiles, and calculated mean glomerular volumes using the Weibel-Gomez stereologic formula (separately for nonsclerosed glomeruli and globally sclerosed glomeruli). We then assessed the relationship of glomerular volume with age, clinical characteristics, and nephrosclerosis on biopsy specimen.Results Compared with kidney donors, patients with tumors were older and more frequently men, obese, diabetic, or hypertensive, had more glomerulosclerosis and interstitial fibrosis on biopsy specimen, and had 12% larger nonsclerosed glomeruli (P<0.001). In both populations, male sex, taller height, obesity, hypertension, and proteinuria associated with larger nonsclerosed glomeruli to a similar extent. In patients with tumors, diabetes, glomerulosclerosis >25%, and interstitial fibrosis >25% also associated with larger nonsclerosed glomeruli. Independent clinical predictors of larger nonsclerotic glomeruli were family history of ESRD, male sex, taller height, obesity, diabetes, and proteinuria. After adjustment for these characteristics, nonsclerotic glomerular volume did not differ between populations and was stable up to age 75 years, after which it decreased with age. Many of these findings were also evident with globally sclerotic glomerular volume.Conclusions Characteristics associated with glomerular volume are consistent between patient populations with low and high levels of comorbidity.

Residential Area Life Expectancy: Association With Outcomes and Processes of Care for Patients With ESRD in the United States

BACKGROUND

The effects of underlying noncodified risks are unclear on the prognosis of patients with end-stage renal disease (ESRD). We aimed to evaluate the association of residential area life expectancy with outcomes and processes of care for patients with ESRD in the United States.

STUDY DESIGN

Retrospective cohort study.

SETTING & PARTICIPANTS

Adult patients with incident ESRD between 2006 and 2013 recorded in the US Renal Data System (n=606,046).

PREDICTOR

The primary exposure was life expectancy in the patient's residential county estimated by the Institute for Health Metrics and Evaluation.

OUTCOMES

Death, placement on the kidney transplant wait list, living and deceased donor kidney transplantation, and posttransplantation graft loss.

RESULTS

Median life expectancies of patients' residences were 75.6 (males) and 80.4 years (females). Compared to the highest life expectancy quintile and adjusted for demographic factors, disease cause, and multiple comorbid conditions, the lowest quintile had adjusted HRs for mortality of 1.20 (95% CI, 1.18-1.22); placement onto the waiting list, 0.68 (95% CI, 0.67-0.70); living donor transplantation, 0.53 (95% CI, 0.51-0.56); posttransplantation graft loss, 1.35 (95% CI, 1.27-1.43); and posttransplantation mortality, 1.29 (95% CI, 1.19-1.39). Patients living in areas with lower life expectancy were less likely to be informed about transplantation, be under the care of a nephrologist, or receive an arteriovenous fistula as the initial dialysis access. Results remained consistent with additional adjustment for zip code-level median income, population size, and urban-rural locality.

LIMITATIONS

Potential residual confounding and attribution of effects to individuals based on residential area-level data.

CONCLUSIONS

Residential area life expectancy, a proxy for socioeconomic, environmental, genetic, and behavioral factors, was independently associated with mortality and process-of-care measures for patients with ESRD. These results emphasize the underlying effect on health outcomes of the environment in which patients live, independent of patient-level factors. These findings may have implications for provider assessments.

Risk Factors for Abnormal Cervical Cytology in Women Undergoing Kidney Transplant Evaluation

OBJECTIVES

Cervical cytology screening has been successful in reducing deaths from cervical cancer. We sought to determine risk factors for abnormal Pap test results in women undergoing kidney transplant evaluation.

MATERILAS AND METHODS

We retrospectively examined women undergoing kidney transplant evaluations from 2008 to 2011. Patients were stratified based on normal cytology and atypical/malignant cytology.

RESULTS

Of 404 patients, 293 patients (72.5%) had normal cytologic findings, whereas 111 (27.5%) had abnormal findings. On univariate logistic regression analyses, patients who had chronic kidney disease with an autoimmune cause (odds ratio = 2.71 [95% confidence interval, 1.41-5.19]; P = .003), previous renal transplants (odds ratio = 2.64 [95% confidence interval, 1.20-5.82], P = .016), or age ≤ 50 years (odds ratio = 1.68 [95% confidence interval, 1.08-2.61], P = .022) were more likely to have abnormal findings. Patients with normal and abnormal findings had similar rates of dialysis use. On multivariate logistic regression, patients who had chronic kidney disease with autoimmune causes (odds ratio = 2.48 [95% confidence interval, 1.26-4.88]; P = .008) and who had previous renal transplants (odds ratio = 2.67 [95% confidence interval, 1.20-5.95]; P = .017) were more likely to have abnormal findings.

CONCLUSIONS

Previous kidney transplant, autoimmune disease, and age ≤ 50 years were associated with abnormalities on cervical cancer screening in our female group of patients. Patients with these characteristics may benefit more from routine cervical cancer screening than other patients evaluated for kidney transplant.

The Utility of Screening Colonoscopy During Kidney Transplant Evaluation

OBJECTIVES

Transplant centers often recommend, but not necessarily require, screening colonoscopies for people over 50 years of age in accordance with the US Preventative Services Task Force guidelines for the general population. We sought to identify risk factors affecting colonoscopy results in renal failure patients undergoing kidney transplant evaluation.

MATERIALS AND METHODS

We retrospectively examined patients undergoing kidney transplant evaluation from 2009 to 2012 (n = 469 patients). Comparisons were made between colonoscopy reports categorized as normal (no finding or hyperplastic polyp) or abnormal (adenomatous polyp or carcinoma).

RESULTS

Of 469 patients who met the study criteria, 303 (64.6%) had normal colonoscopies and 166 (35.4%) had abnormal colonoscopies. Logistic regression analysis showed that male sex (odds ratio = 2.09; 95% confidence interval, 1.37-3.20; P = .001) and increasing age (odds ratio = 1.04; 95% confidence interval, 1.01-1.08; P = .019) were more likely to correspond to abnormal findings. Those with dialysis vintage (length of time on dialysis) up to 3 years (odds ratio = 2.10; 95% confidence interval, 1.09-4.06; P = .027) and hypertension as the cause of renal failure (odds ratio = 1.79; 95% confidence interval, 1.05-2.87; P = .002) had more abnormal findings. No differences in length of evaluation, rate of being listed for transplant, and rate of transplant were shown.

CONCLUSIONS

The overall rate of adenomatous findings on colonoscopy was higher among patients with pretransplant end-stage renal disease than in the general population, as shown in other studies. Age, sex, dialysis vintage up to 3 years, and hypertensive renal failure were associated with adenomatous polyps of the colon in this study population. Because adenomatous polyp rates are high in patients with chronic kidney disease who are undergoing transplant evaluation and colonoscopic findings do not appear to delay transplant evaluations or listing rates, screening colonoscopies should be encouraged.

Fulminant endocarditis and disseminated infection caused by carbapenem-resistant Acinetobacter baumannii in a renal-pancreas transplant recipient

Acinetobacter baumannii is an important cause of healthcare-associated infections, and is particularly problematic among patients who undergo organ transplantation. We describe a case of fulminant sepsis caused by carbapenem-resistant A. baumannii harboring the blaOXA-23 carbapenemase gene and belonging to international clone II. This isolate led to the death of a patient 6 days after simultaneous kidney-pancreas transplantation. Autopsy findings revealed acute mitral valve endocarditis, myocarditis, splenic and renal emboli, peritonitis, and pneumonia. This case highlights the severe nature of certain A. baumannii infections and the vulnerability of transplanted patients to the increasingly intractable "high-risk" clones of multidrug-resistant organisms.

T-cell immune monitoring by the ELISPOT assay for interferon gamma

The enzyme-linked immunosorbent spot (ELISPOT) assay for interferon gamma has been available for more than twenty years and has been used for a number of applications, including the monitoring of T cell immunity in solid organ transplant recipients. Studies from single centers indicate that heightened T cell alloreactivity measured with this assay correlates with acute and chronic rejection and with poor long-term allograft function. The assay has been used not only to assess T cell reactivity after transplantation, but also as a tool for assessing immune risk prior to transplantation. Additional work is needed to validate the assay in larger multicenter clinical trials.

Donor phosphorus levels and recipient outcomes in living-donor kidney transplantation

BACKGROUND AND OBJECTIVES

In living-donor kidney transplantation, various donor factors, including gender, age, and baseline kidney function, predict allograft function and recipient outcomes after transplantation. Because higher phosphorus is predictive of vascular injury in healthy adults, the effect of donor phosphorus levels on recipient renal function after transplantation was investigated.

DESIGN, SETTING, PARTICIPANTS, AND MEASUREMENTS

Phosphorus levels in 241 living donors were analyzed from a 7-year period, and recipient renal function and acute rejection at 1 year posttransplantation were examined controlling for other influencing factors, including multiple donor variables, HLA matching, and acute rejection.

RESULTS

Female and African-American donors had significantly higher phosphorus levels predonation. By multivariable analysis, higher donor phosphorus correlated with higher recipient serum creatinine (slope=0.087, 95% confidence interval [CI]: 0.004 to 0.169, P=0.041) and lower recipient estimated GFR (slope=-4.321, 95% CI: -8.165 to -0.476, P=0.028) at 12 months. Higher donor phosphorus also displayed an independent correlation with biopsy-proven acute rejection and delayed or slow graft function after transplantation.

CONCLUSIONS

In a cohort of living kidney donors, higher donor phosphorus correlated with female gender and African-American ethnicity and was an independent risk factor for early allograft dysfunction after living-donor kidney transplantation.

Influence of African-American ethnicity on acute rejection after early steroid withdrawal in primary kidney transplant recipients

BACKGROUND AND PURPOSE

The influence of African-American ethnicity on outcomes of kidney transplant recipients subjected to early steroid withdrawal remains controversial. Recent studies that suggest no higher risk among African Americans may be biased by recruitment of relatively small number of African Americans or by patient selection. We compared outcomes of African Americans to non-African Americans in a center in which early steroid withdrawal has become the standard of practice.

METHODS

This was a single-center prospective study of 133 consecutive patients receiving primary kidney transplants between January 2006 and December 2008, followed for >or=3 months, and managed with a similar immunosuppression regimen that included induction antibody therapy, tacrolimus, mycophenolate mofetil, and withdrawal of steroids on postoperative day 5. Acute rejection and other outcomes were compared in African-American patients (n = 55) and compared with those of non-African-American patients (n = 78).

RESULTS

During the first 12 months after early steroid withdrawal, African-American patients experienced a significantly higher cumulative incidence of acute rejection than non-African Americans (23.6% vs 7.7%; P = .020). Using multivariate logistic regression, ethnicity (odds ratio 3.33; P = .047) and HLA mismatch (odds ratio 1.44; P = .041) were significantly correlated with acute rejection independent of recipient age, gender, historical peak panel reactive antibody level (PRA) or PRA at time of transplant, time on dialysis, or donor source.

CONCLUSIONS

African Americans are at increased risk of acute rejection after early steroid withdrawal, particularly when they receive kidneys from poorly matched donors.

Clinical predictors of proteinuria after conversion to sirolimus in kidney transplant recipients

Proteinuria is an increasingly recognized effect of sirolimus (SRL) therapy in kidney transplant recipients. Predictors of proteinuria after conversion to SRL are not well described, and in particular the risk in African-American (AA) kidney recipients is unknown. We sought to analyze risk factors for proteinuria with SRL therapy in a cohort of 39 patients (44% AA) converted from tacrolimus to SRL at a mean time of 4 months posttransplantation. Patients were maintained on therapy with mycophenolate mofetil while most patients underwent early steroid withdrawal. Urinary protein to creatinine ratio (Up/cr) at a mean of 14 months postconversion increased to > or =500 mg/g in 65% of AAs versus 14% of non-AAs (p = 0.001). Mean arterial blood pressure at the time of conversion and pretransplant proteinuric kidney disease were also predictors of proteinuria after SRL conversion. In conclusion, AAs appear to be at high risk for proteinuria and should be monitored closely after conversion to SRL in calcineurin inhibitor sparing protocols.

Pretransplant cellular alloimmunity as assessed by a panel of reactive T cells assay correlates with acute renal graft rejection

BACKGROUND

The panel reactive antibody test (PRA) is an established method for assessing posttransplant risk of immune-mediated graft injury. The panel of reactive T cell assay (PRT) in which transplant candidates' peripheral blood mononuclear cells are tested for reactivity to a panel of allogenic stimulator cells by the IFN-gamma enzyme-linked immunosorbent spot assay analogously assesses the strength of the pretransplant effector-memory alloreactive T cell repertoire.

METHODS

PRT assays were performed in 30 kidney transplant candidates and results were correlated with acute rejection (AR). A positive PRT assay was defined as a response to at least 75% of the stimulators tested.

RESULTS

A positive pretransplant PRT test was observed in 11 of 30 (37%) patients, and AR within 1 year posttransplantation was seen in 7 of 30 (23%) subjects. Six of the seven (86%) patients with AR were PRT-positive (P=0.01) whereas only one of seven (14%) patients with a PRA greater than 15% had AR. The mean pretransplant PRT percentage was 40% for patients with no AR versus 81% for patients with AR (P=0.01). Estimated glomerular filtration rate (mL/min/1.73 m2) showed a trend towards a lower value in PRT-positive (48+/-15) versus PRT-negative (55+/-13) individuals.

CONCLUSIONS

The data suggest that pretransplant PRT screening can identify patients at risk for posttransplant cellular immune mediated graft injury despite the absence of humoral allosensitization. Once confirmed by larger prospective trials, PRT screening could be used to guide clinical decision-making with regard to choosing donor organs and individualizing immunosuppression regimens.

Use of sirolimus in solid organ transplantation

Sirolimus is a mammalian target of rapamycin (mTOR) inhibitor that inhibits cell cycle progression and has proven to be a potent immunosuppressive agent for use in solid organ transplant recipients. The drug was initially studied as an adjunct to ciclosporin (cyclosporine) to prevent acute rejection in kidney transplant recipients. Subsequent studies have shown efficacy when combined with a variety of other immunosuppressive agents. The most common adverse effects of sirolimus are hyperlipidaemia and myelosuppression. The drug has unique antiatherogenic and antineoplastic properties, and may promote immunological tolerance and reduce the incidence of chronic allograft nephropathy. Although sirolimus is relatively non-nephrotoxic when administered as monotherapy, it pharmacodynamically enhances the toxicity of calcineurin inhibitors. Ironically, the drug has been used to facilitate calcineurin inhibitor-free protocols designed to preserve renal function after solid organ transplantation. Whether sirolimus can be used safely over the long term with low doses of calcineurin inhibitors requires further study. The use of sirolimus as a corticosteroid-sparing agent also remains to be proven in controlled trials. Postmarketing studies have revealed a number of unforeseen adverse effects including impaired wound healing and possibly proteinuria, oedema, pneumonitis and thrombotic microangiopathy. Overall, sirolimus is a powerful agent when used judiciously with other available immunosuppressants. As is true for all immunosuppressive drugs available for treatment of solid organ transplant recipients, the efficacy of the drug must be balanced against its considerable adverse effects.

Hemodialysis vintage, black ethnicity, and pretransplantation antidonor cellular immunity in kidney transplant recipients

Prolonged exposure to dialysis before transplantation and black ethnicity are known risk factors for acute rejection and graft loss in kidney transplant recipients. Because the strength of the primed antidonor T cell repertoire before transplantation also is associated with rejection and graft dysfunction, this study sought to determine whether hemodialysis (HD) vintage and/or black ethnicity affected donor-directed T cell immunity. An enzyme-linked immunosorbent spot (ELISPOT) assay was used to measure the frequency of peripheral T cells that expressed IFN-gamma in response to donor stimulator cells before transplantation in 100 kidney recipients. Acute rejection occurred in 38% of ELISPOT (+) patients versus 14% of ELISPOT (-) patients (P = 0.008). The median (HD) vintage was 46 mo (0 to 125 mo) in ELISPOT (+) patients versus 24 mo (0 to 276 mo) in ELISPOT (-) patients (P = 0.009). Black recipients had a greater median HD vintage (55 versus 14 mo in nonblack recipients; P < 0.001). Black recipients with less HD exposure had a low incidence of an ELISPOT (+) test, similar to nonblack recipients. Among variables examined, only HD vintage remained a significant positive correlate with an ELISPOT (+) result (odds ratio per year of HD 1.3; P = 0.003). These data suggest that the risk for developing cross-reactive antidonor T cell immunity increases with longer HD vintage, providing an explanation for the previously observed relationship between increased dialysis exposure and worse posttransplantation outcome. Longer HD vintage may also explain the increased T cell alloreactivity that previously was observed in black kidney recipients.

Long-term graft outcomes after steroid withdrawal in African American kidney transplant recipients receiving sirolimus and tacrolimus

BACKGROUND

We previously reported excellent short-term outcomes in African American kidney transplant patients receiving tacrolimus/sirolimus and withdrawn from corticosteroid therapy three months after transplantation. We now report the long-term outcomes of patients subjected to this protocol.

METHODS

In all, 47 African American kidney transplant recipients were enrolled in an uncontrolled trial in which they were initially treated with sirolimus, tacrolimus, and corticosteroids, without antibody induction therapy. Eligible patients were withdrawn from prednisone between three and five months posttransplant, and followed for acute rejection and changes in renal function. Outcomes (group 1, n=32) were compared to those of patients deemed not to be candidates for steroid withdrawal (group 2, n=15).

RESULTS

After a mean follow-up of 48.5 months, 13 of 32 patients (41%) in group 1 developed acute rejection; only 13 patients (41%) remain steroid-free. Nine of 13 rejection episodes were associated with noncompliance. Graft loss occurred in 8 of 32 patients (25%) in group 1 and in 5 of 15 patients (33%) in group 2 (P=NS). Serum creatinine rose from 1.4+/-0.41 to 2.45+/-1.7 mg/dL in group 1 (P=0.004) and from 2.1+/-0.45 to 2.62+/-1.2 mg/dL (P=NS) in group 2. Among 13 patients in group 1 who remain steroid-free, creatinine concentration has risen from 1.28+/-.0.37 prior to steroid withdrawal to 1.64+0.54 at last follow-up (P=0.027).

CONCLUSIONS

Late noncompliance and/or rejection in African Americans withdrawn from steroids have a negative impact on long-term graft function and survival. Steroid withdrawal may be associated with long-term deterioration of renal function, even in the absence of overt acute rejection.

Differences in proteinuria and graft function in de novo sirolimus-based vs. calcineurin inhibitor-based immunosuppression in live donor kidney transplantation

BACKGROUND

Calcineurin inhibitor(CNI)-free protocols using sirolimus (SRL) in kidney transplantation have proven effective, although reports have linked SRL to proteinuria. We sought to investigate this link and its impact on graft function.

METHODS

We retrospectively analyzed 184 live donor kidney transplant recipients who exclusively received de novo CNI-based (n = 106) or SRL-based (n = 78) regimens. Estimated glomerular filtration rate (GFR) and semi-quantitative dipstick proteinuria measurements were obtained at one, six, 12, and 24 months and six and 12 months, respectively.

RESULTS

SRL-treated patients had higher frequencies of proteinuria (> or =1+) at 6 months (40.8% vs. 21.4%, P = 0.006) and 12 months (37.8% vs. 18.4%, P = 0.004) than those treated with CNI. Independent predictors of proteinuria at 12 months were GFR at one month (OR 0.62 per 10 ml/min/1.73 m, P<0.001), delayed graft function (OR 11.5, P = 0.02), and a SRL-based regimen (OR 4.18, P=0.002). By univariable analysis, SRL vs. CNI patients had higher GFR at each point. SRL-treated patients without proteinuria had higher GFR at 12 months compared to CNI-treated patients with and without proteinuria (66 vs. 50 or 56 ml/min/1.73 m, P < 0.05). No difference in GFR was seen between SRL-treated patients with proteinuria vs. CNI-treated patients without proteinuria (57 vs. 56 ml/min/1.73 m, P > 0.05). Absence of proteinuria and a SRL-based regimen remained independently associated FS with higher GFR at 12 months by multivariable analyses.

CONCLUSIONS

De novo SRL-based immunosuppression is associated with a higher frequency of semi-quantitative proteinuria, however, estimated graft function at 1 year posttransplant remains superior to that of CNI-treated patients. Nevertheless, the long-term implications of these findings need to be determined.

Steroid Sparing in Kidney Transplantation: Changing Paradigms, Improving Outcomes, and Remaining Questions

The widely known adverse effects of long-term therapy with corticosteroids have motivated increasing interest in steroid-free immunosuppression for kidney transplant recipients. Results from recent trials that used newer immunosuppressants to facilitate elimination of steroids suggest better short-term results than were achieved in an earlier era. However, the best results have been reported in uncontrolled trials of low-risk patients or in randomized trials with relatively short periods of follow-up. Increasingly, the therapeutic paradigm has shifted from late withdrawal of steroids to very early withdrawal after transplantation or even complete avoidance. Induction antibody therapy has been used routinely in the most successful trials that involved early steroid withdrawal or avoidance. Although the outcomes of kidney transplant recipients who are treated with steroid-free immunosuppression are improving steadily, there still is room for concern in recommending this strategy as a standard of practice.

Improved Renal Function after Conversion from Tacrolimus/Sirolimus to Tacrolimus/Mycophenolate Mofetil in Kidney Transplant Recipients

BACKGROUND

There is limited data on the potential nephrotoxicity of sirolimus (SRL) and tacrolimus (TAC) in combination.

METHODS

We reviewed the course of 97 kidney transplant patients treated with SRL and reduced-dose TAC. Conversion from SRL to mycophenolate mofetil (MMF) was prescribed in a minority (n = 19) for various nonrenal side effects. We compared outcomes of converted patients to those remaining on TAC/SRL (n = 78).

RESULTS

TAC levels were increased in converters (P = 0.009). Rejection rates were similar between groups over 18 months (21% vs. 16%, p = ns). Serum creatinine (Cr) and MDRD glomerular filtration rate (GFR) were similar between groups at nadir and six-months, but at 18 months the percent change from six-month Cr was +17% in non-converters vs. -10% in converters (P = 0.004 for the difference). The difference in GFR between groups at 18 months was also significant (P = 0.01). By multivariate analysis, only conversion to MMF was associated with a greater percent change in Cr from 6 to 18 months (P = 0.015). Conversion to MMF also correlated with higher GFR at 18 months independent of rejection, delayed graft function, and ethnicity.

CONCLUSIONS

Conversion from TAC/SRL to TAC/MMF led to improved renal function despite increased TAC exposure after conversion.

Pre-transplant IFN-gamma ELISPOTs are associated with post-transplant renal function in African American renal transplant recipients

Final crossmatch testing is routinely used to assess the risk of antibody-mediated graft injury/rejection post-transplant. Analogously, we postulated that quantitative measurements of anti-donor effector/memory T cells pre-transplant would independently assess post-transplant risk. To address this hypothesis, we determined the frequencies of pre-transplant, donor-specific interferon-gamma (IFN-gamma) enzyme-linked immunosorbent spots (ELISPOTs) and correlated the results with post-transplant outcomes in 37 African American recipients of deceased donor kidney transplants treated with tacrolimus- and sirolimus-based immunosuppression. A positive ELISPOT test (>25 spots/300,000 cells) was detected in 14 (38%) of 37 patients. The incidence of biopsy-proven acute rejection was 50% (7/14) in ELISPOT-positive versus 17% (4/23) in ELISPOT-negative patients (p=0.036). Calculated glomerular filtration rate (MDRD) at 12 months was 37+/-16 mL/min in ELISPOT-positive versus 55+/-20 mL/min in ELISPOT-negative patients (p=0.01). ELISPOT status remained a correlate of allograft function at 12 months by linear regression analysis (p=0.001), independent of rejection and other contributing variables. Pre-transplant donor-directed IFN-gamma ELISPOT assessment of anti-donor cellular immunity may function as a 'cellular crossmatch' and independently correlates with renal allograft function in African Americans receiving tacrolimus- and sirolimus-based immunosuppression.

Comparative effects of sirolimus and mycophenolate mofetil on erythropoiesis in kidney transplant patients

Anemia and erythrocytosis (PTE) are common after kidney transplantation. We sought to determine the influence of sirolimus compared to mycophenolate mofetil (MMF) on post-transplant erythropoiesis. A total of 214 patients with recent kidney or kidney-pancreas transplants were treated with either sirolimus-based (n = 87) or MMF-based (n = 127) therapy. At 12 months, the prevalence of anemia was 31% with MMF and 57% with sirolimus (p < 0.001). Linear regression was used to examine the independent influence of sirolimus on hemoglobin at 12 months, controlling for multiple factors including gender and renal function. Sirolimus remained a significant correlate of lower hemoglobin in all patients (slope =-1.060, 95% CI: -1.76 to -0.362, p = 0.003), and in patients without PTE (slope =-0.671, 95% CI: -1.32 to -0.028, p = 0.041). PTE, defined as a persistent hematocrit above 51%, occurred in 19% with MMF and 7% with sirolimus (p = 0.013). PTE was examined using logistic regression analysis. Sirolimus use correlated negatively with PTE (odds ratio with sirolimus = 0.33, 95% CI: 0.12 to 0.89, p = 0.028). Our results indicate that, compared to treatment with MMF, treatment of kidney or kidney-pancreas recipients with sirolimus is associated with a higher prevalence of anemia, lower hemoglobin levels and lower incidence of PTE.

A randomized controlled trial comparing intermittent with continuous dialysis in patients with ARF

BACKGROUND

Despite the widespread use of continuous renal replacement therapy in critically ill patients with acute renal failure (ARF), there are few data supporting its benefits over conventional intermittent hemodialysis (IHD). We sought to analyze differences in survival between modalities in a study that compared continuous venovenous hemodialysis (CVVHD) with IHD.

METHODS

Eighty critically ill patients with ARF requiring dialysis were randomized after stratification by severity of illness to treatment with CVVHD or IHD.

RESULTS

There were no differences in survival or renal recovery between groups. In patients who died, mean survival time was 10.7 +/- 11.2 days for the IHD group versus 14.3 +/- 16.1 days for the CVVHD group (P = not significant). There was greater net volume removal in the CVVHD group during 72 hours. Declines in urine output during 72 hours were similar between groups. Mean arterial pressure off and on dialysis therapy was analyzed retrospectively. There was a significant decrease in mean arterial pressure for patients on IHD therapy not seen in those on CVVHD therapy, but this did not lead to a survival advantage.

CONCLUSION

Despite greater volume control, CVVHD did not lead to an improvement in survival, preservation of urine output, or renal recovery compared with IHD in patients with ARF.