Marked variation in the definition and diagnosis of delayed graft function: a systematic review

BACKGROUND

The term delayed graft function (DGF) is commonly used to describe the need for dialysis after receiving a kidney transplant. DGF increases morbidity after transplantation, prolongs hospitalization and may lead to premature graft failure. Various definitions of DGF are used in the literature without a uniformly accepted technique to identify DGF.

METHODS

We performed a systematic review of the literature to identify all of the different definitions and diagnostic techniques to identify DGF.

RESULTS

We identified 18 unique definitions for DGF and 10 diagnostic techniques to identify DGF.

CONCLUSIONS

The utilization of heterogeneous clinical criteria to define DGF has certain limitations. It will lead to delayed and sometimes inaccurate diagnosis of DGF. Hence a diagnostic test that identifies DGF reliably and early is necessary. Heterogeneity, in the definitions used for DGF, hinders the evolution of a diagnostic technique to identify DGF, which requires a gold standard definition. We are in need of a new definition that is uniformly accepted across the kidney transplant community. The new definition will be helpful in promoting better communication among transplant professionals and aids in comparing clinical studies of diagnostic techniques to identify DGF and thus may facilitate clinical trials of interventions for the treatment of DGF.

Single-Nephron Glomerular Filtration Rate in Healthy Adults

BACKGROUND

The glomerular filtration rate (GFR) assesses the function of all nephrons, and the single-nephron GFR assesses the function of individual nephrons. How the single-nephron GFR relates to demographic and clinical characteristics and kidney-biopsy findings in humans is unknown.

METHODS

We identified 1388 living kidney donors at the Mayo Clinic and the Cleveland Clinic who underwent a computed tomographic (CT) scan of the kidney with the use of contrast material and an iothalamate-based measurement of the GFR during donor evaluation and who underwent a kidney biopsy at donation. The mean single-nephron GFR was calculated as the GFR divided by the number of nephrons (calculated as the cortical volume of both kidneys as assessed on CT times the biopsy-determined glomerular density). Demographic and clinical characteristics and biopsy findings were correlated with the single-nephron GFR.

RESULTS

A total of 58% of the donors were women, and the mean (±SD) age of the donors was 44±12 years. The mean GFR was 115±24 ml per minute, the mean number of nephrons was 860,000±370,000 per kidney, and the mean single-nephron GFR was 80±40 nl per minute. The single-nephron GFR did not vary significantly according to age (among donors <70 years of age), sex, or height (among donors ≤190 cm tall). A higher single-nephron GFR was independently associated with larger nephrons on biopsy and more glomerulosclerosis and arteriosclerosis than would be expected for age. A higher single-nephron GFR was associated with a height of more than 190 cm, obesity, and a family history of end-stage renal disease.

CONCLUSIONS

Among healthy adult kidney donors, the single-nephron GFR was fairly constant with regard to age, sex, and height (if ≤190 cm). A higher single-nephron GFR was associated with certain risk factors for chronic kidney disease and certain kidney-biopsy findings. (Funded by the National Institute of Diabetes and Digestive and Kidney Diseases.).

Development and validation of GFR-estimating equations using diabetes, transplant and weight

BACKGROUND

We have reported a new equation (CKD-EPI equation) that reduces bias and improves accuracy for GFR estimation compared to the MDRD study equation while using the same four basic predictor variables: creatinine, age, sex and race. Here, we describe the development and validation of this equation as well as other equations that incorporate diabetes, transplant and weight as additional predictor variables.

METHODS

Linear regression was used to relate log-measured GFR (mGFR) to sex, race, diabetes, transplant, weight, various transformations of creatinine and age with and without interactions. Equations were developed in a pooled database of 10 studies [2/3 (N = 5504) for development and 1/3 (N = 2750) for internal validation], and final model selection occurred in 16 additional studies [external validation (N = 3896)].

RESULTS

The mean mGFR was 68, 67 and 68 ml/min/ 1.73 m(2) in the development, internal validation and external validation datasets, respectively. In external validation, an equation that included a linear age term and spline terms in creatinine to account for a reduction in the magnitude of the slope at low serum creatinine values exhibited the best performance (bias = 2.5, RMSE = 0.250) among models using the four basic predictor variables. Addition of terms for diabetes and transplant did not improve performance. Equations with weight showed a small improvement in the subgroup with BMI <20 kg/m(2).

CONCLUSIONS

The CKD-EPI equation, based on creatinine, age, sex and race, has been validated and is more accurate than the MDRD study equation. The addition of weight, diabetes and transplant does not significantly improve equation performance.

Recipient outcomes for expanded criteria living kidney donors: the disconnect between current evidence and practice

Older individuals or those with medical complexities are undergoing living donor nephrectomy more than ever before. Transplant outcomes for recipients of kidneys from these living expanded criteria donors are largely uncertain. We systematically reviewed studies from 1980 to June 2008 that described transplant outcomes for recipients of kidneys from expanded criteria living donors. Results were organized by the following criteria: older age, obesity, hypertension, reduced glomerular filtration rate (GFR), proteinuria and hematuria. Pairs of reviewers independently evaluated each citation and abstracted data on study and donor characteristics, recipient survival, graft survival, serum creatinine and GFR. Transplant outcomes for recipients of kidneys from older donors (> or =60 years) were described in 31 studies. Recipients of kidneys from older donors had poorer 5-year patient and graft survival than recipients of kidneys from younger donors [meta-analysis of 12 studies, 72% vs. 80%, unadjusted relative risk (RR) of survival 0.89, 95% confidence interval (CI) 0.83-0.95]. In meta-regression, this association diminished over time (1980s RR 0.79, 95% CI 0.65-0.96 vs. 1990s RR 0.91, 95% CI 0.85-0.99). Few transplant outcomes were described for other expanded criteria. This disconnect between donor selection and a lack of knowledge of recipient outcomes should give transplant decision-makers pause and sets an agenda for future research.

Transient versus persistent BK viremia and long-term outcomes after kidney and kidney-pancreas transplantation

BACKGROUND AND OBJECTIVES

The objective was to study the long-term impact of transient versus persistent BK viremia on kidney transplant outcomes.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

In total, 609 recipients who underwent kidney transplant from 2007 to 2011 were screened at months 1-12 for the occurrence of polyomavirus BK viremia; 130 patients (21.7%) developed BK viremia during the first year post-transplant. BK viremia patients were classified according to duration of infection (more or less than 3 months), and BK viral loads (more or less than 10,000 copies/ml) were classified as transient low viremia (n=42), transient high viremia (n=18), persistent low viremia (n=23), and persistent high viremia (n=47). All patients were followed a median of 36 (3-66) months. The rates of BK polyomavirus-associated nephropathy, acute rejection, and 1-year graft function were compared with the polyomavirus BK-negative control group.

RESULTS

Patient and graft survival were not significantly different among the groups. Graft function (creatinine; milligrams per deciliter) at 1 year was significantly worse in the persistent high viremia (1.75±0.6) and transient high viremia (1.85±0.7) groups compared with aviremic controls (1.47±0.4; P=0.01 and P=0.01, respectively). The incidence of BK polyomavirus-associated nephropathy was limited to the persistent high viremia group (1.3%, P<0.001). The transient high viremia (50%) and persistent high viremia (34%) groups showed significantly (P=0.01) increased incidence of acute rejection versus aviremic controls (21.5%), transient low viremia (19%), or persistent low viremia (17.3%) groups.

CONCLUSION

Low viral load BK viremia, either transient or persistent, was not associated with long-term transplant outcomes. Persistent high viremia was associated with a greater risk for BK polyomavirus-associated nephropathy and subsequent graft dysfunction. Although transient high viremia was not associated with BK polyomavirus-associated nephropathy, it was associated with worse graft function. These data support the role of surveillance for BK viremia after transplant.

The impact of surveillance and rapid reduction in immunosuppression to control BK virus-related graft injury in kidney transplantation

We prospectively screened 609 consecutive kidney (538) and kidney-pancreas (71) transplant recipients for BK viremia over a 4-year interval using polymerase chain reaction viral load detection and protocol kidney biopsies. We found that BK viremia is common at our center: total cases 26.7%, cases during first year 21.3% (mean 4 months), and recipients with ≥ 10 000 copies/ml 12.3%. We found few predictive clinical or demographic risk factors for any BK viremia or viral loads ≥ 10,000 copies/ml, other than prior treatment of biopsy confirmed acute rejection and/or higher immunosuppressive blood levels of tacrolimus (P = 0.001) or mycophenolate mofetil (P = 0.007). Viral loads at diagnosis (<10 000 copies/ml) demonstrated little impact on graft function or survival. However, rising copy numbers demand early reductions in immunosuppressive drug doses of at least 30-50%. Viral loads >185 000 copies/ml at diagnosis were predictive of BK virus-associated nephropathy (BKVAN; OR: 113.25, 95% CI: 17.22-744.6, P < 0.001). Surveillance for BK viremia and rapid reduction of immunosuppression limited the incidence of BKVAN to 1.3%. The addition of leflunomide or ciprofloxacin to immunosuppressive dose reduction did not result in greater rates of viral clearance. These data support the role of early surveillance for BK viremia to limit the impact on transplant outcome, although the most effective schedule for screening awaits further investigation.

B Cell Receptor Genes Associated With Tolerance Identify a Cohort of Immunosuppressed Patients With Improved Renal Allograft Graft Function

We previously reported that two B cell receptor genes, IGKV1D-13 and IGKV4-1, were associated with tolerance following kidney transplantation. To assess the potential utility of this "signature," we conducted a prospective, multicenter study to determine the frequency of patients predicted tolerant within a cohort of patients deemed to be candidates for immunosuppressive minimization. At any single time point, 25-30% of patients were predicted to be tolerant, while 13.7% consistently displayed the tolerance "signature" over the 2-year study. We also examined the relationship of the presence of the tolerance "signature" on drug use and graft function. Contrary to expectations, the frequency of predicted tolerance was increased in patients receiving tacrolimus and reduced in those receiving corticosteroids, mycophenolate mofetil, or Thymoglobulin as induction. Surprisingly, patients consistently predicted to be tolerant displayed a statistically and clinically significant improvement in estimated glomerular filtration rate that increased over time following transplantation. These findings indicate that the frequency of patients consistently predicted to be tolerant is sufficiently high to be clinically relevant and confirm recent findings by others that immunosuppressive agents impact putative biomarkers of tolerance. The association of a B cell-based "signature" with graft function suggests that B cells may contribute to the function/survival of transplanted kidneys.

Prevalence and clinical course of BK virus nephropathy in pancreas after kidney transplant patients

The influence of BK virus nephropathy (BKVN) in pancreas after kidney (PAK) transplantation is unclear. A retrospective analysis of PAK transplants performed at our center was conducted to determine the impact of BKVN. Among 40 PAK transplants performed using sequential immunosuppression, four patients developed BKVN, as defined by a >20% rise in serum creatinine and BK viremia (BK plasma load >4 log copies/mL), at a median of 19 months following PAK. In all four patients, treatment of BKVN consisted of reduction in tacrolimus, cessation of mycophenolate mofetil, and introduction of leflunomide. With this approach, two patients experienced improvement or stabilization of renal function. The remaining two patients progressed to dialysis dependence despite treatment. Plasma BK load < or =5 log copies/mL was associated with graft preservation. Gender, age, delay between transplants, cumulative Thymoglobulin dose, and type of kidney donor were not associated with BK virus infection. Pancreas graft rejection or dysfunction was not observed with the above immunosuppression modification. Mean amylase and lipase > or =6 months following BKVN treatment remained normal. BKVN is an important cause of kidney allograft loss in PAK patients. Screening and early treatment of BKVN may enable preservation of kidney and pancreas grafts.

Preemptive renal transplant candidate survival, access to care, and renal function at listing

BACKGROUND

Preemptive transplantation is associated with better survival and transplant outcomes than transplantation after dialysis has been started. The purpose of this study is to examine associations between candidate characteristics, likelihood of preemptive transplant, candidate survival and renal function (RF) at the time of listing.

METHODS

We looked at 57 677 solitary renal transplant candidates from the Scientific Registry of Transplant Recipients database listed prior to dialysis from 2000 to 2009. Using multivariable models, we measured associations between candidate characteristics, likelihood of preemptive transplantation, candidate survival and RF at listing.

RESULTS

Candidates with higher RF at listing were more likely to be male, Caucasian, diabetic, be a prior transplant recipient and have more education. Higher RF at listing was strongly associated with greater likelihood of receipt of preemptive transplant [adjusted odds ratio = 1.45, 95% confidence interval (CI) 1.38-1.51] and conferred a significant survival advantage [adjusted hazards ratio = 0.84, 95% CI 0.79-0.89, per 5 mL/min/1.73 m(2)].

CONCLUSIONS

Patient characteristics associated with higher RF at listing suggest differences in access to care. Given that higher RF at the time of listing was also significantly associated with greater likelihood of preemptive transplantation and better survival prior to transplantation, our results suggest that listing at higher levels of RF may improve transplant candidate outcomes.

An opt-out model for kidney transplant referral: The time has come

Disparities that affect equity in access to kidney transplantation for patients with kidney failure have been well described. Many robust clinical trials have tested the effectiveness of interventions to reduce disparities and equilibrate access to kidney transplantation. Moreover, policy changes have been enacted to achieve the same aims. Despite these efforts, rates of kidney transplant waitlisting within the first year of end-stage kidney disease have remained unchanged over the past 2 decades, while incident rates of end-stage kidney disease have climbed. Because prior interventions have not durably increased transplant access, disruptive change is clearly needed. The Advancing American Kidney Health Executive Order sets bold goals to transform kidney care for patients and caregivers. In this spirit, we discuss an Opt-Out for Transplant Referral Model as a compelling solution to improve equity in access to kidney transplantation.

Contrasting patterns of viral load response in transplant recipients with BK polyomavirus DNAemia on leflunomide therapy

BACKGROUND

Reduction in immunosuppression is considered the therapy of proven benefit for BKV infection in renal transplantation, but the use of leflunomide has also been reported. It was observed at this center that the patterns of viral load response while on leflunomide appear to fall into two distinct types.

METHODS

Medical records of 22 kidney and kidney-pancreas recipients at a single center who received leflunomide therapy for BKV DNAemia were reviewed. Information was collected on demographics, BKV viral loads, other antiviral therapy, immunosuppressive drug levels and doses, adverse effects, and graft and patient outcomes.

RESULTS

Eighteen of 22 cleared BKV viremia, and 12 of 22 had preserved allograft function; only two graft losses occurred in the screening era among leflunomide-treated patients. Two patterns of viral load reduction were observed, termed the "smooth" and the "zigzag" pattern, which differed in mean time to clear of BKV DNA (2.9 vs. 19.5 months, p = 0.0073). Graft preservation was correlated with lower serum creatinine (SCr) at the start of leflunomide therapy.

CONCLUSIONS

Long courses and "zigzag" fluctuations in viral load can occur in patients who eventually clear BKV on leflunomide with preserved allograft function. Intermittent increases in viral load do not necessarily portend therapeutic failure. Although the utility of leflunomide is still debated in the transplant community, this information may be useful to clinicians who choose to use it in selected patients.

Natural killer-mediated cytotoxicity in patients with laryngeal carcinoma

Natural killer (NK)-mediated cytotoxicity against the K562 cell line was evaluated in normal subjects and in patients with laryngeal cancer. Results showed reduced lymphocyte cytotoxicity in patients with neoplastic disease and further reduction in NK activity following postoperative radiation therapy. The authors discuss the possibility of using this test in the immunological monitoring of patients with laryngeal carcinoma.

Waldenström-like immunocytic lymphoma with IgG serum M component

A case of immunoproliferative disorder with clinical features of Waldenström's disease but with an IgG-k instead of IgM serum M component is described. The lymphocyte population in the bone marrow, blood and lymph nodes was studied by rosette test, culture with PHA and immunofluorescence staining. Most of the bone marrow lymphocytes had membrane IgG. This case represents an intermediate form between myeloma and Waldenström's disease, thus supporting the unitarian concept of all the immunoproliferative disorders.

Production of Leukocyte Migration Inhibition Factor by Lymphocytes of Larynx Cancer Patients Stimulated by Laryngeal Carcinoma Solubilized Membrane Antigens

The production of leukocyte migration inhibition factor (LIF) from lymphocytes after stimulation with 3 M KCl soluble tumor and normal mucosa extracts was investigated in 30 patients with laryngeal carcinoma at different development stages and in 30 normal donors. The experiments were performed in heterologous and autologous systems. In heterologous systems 3 M KCl tumor extracts induced LIF production by heterologous lymphocytes from patients in 91 % of the cases, and normal mucosa extracts induced LIF production by heterologous lymphocytes from patients in 73 % of the cases and from normal donors in 90 % of the cases. In autologous systems 3 M KCl tumor extracts induced LIF production by autologous lymphocytes from the same patients in 65 % of the cases, whereas the normal laryngeal mucosa extracts induced LIF production by the same autologous lymphocytes in the 6 % of the cases. The high positivity percentage of the test in heterologous systems could be related to differences in the major histocompatibility complex. The 65 % test positivity in autologous systems using tumor extracts could be related to the presence of tumor associated antigens.

Primary gastric lymphoid proliferations: immunological criteria to distinguish gastric lymphoma from reactive hyperplasia

A group of six patients with a marked gastric lymphoid "hyperplasia", two of these with generalised lymphoma and the others suspected for primary gastric lymphoma, were investigated to discriminate between simple reactive hyperplasias and lymphomatous proliferations. Microscopical and ultrastructural examinations were not useful for this purpose but immunological data can give evidence of a two-fold nature of gastric lymphoid hyperplasia. Some cases are without immunological disorders, others are met with peripheral blood signs of immunological alterations similar to those observed in malignant lymphomas and in chronic lymphocytic leukemia. Only these latter cases should, in our opinion, be regarded as primitive gastric lymphomas.

Association between dd-cfDNA levels, de novo donor specific antibodies, and eGFR decline: An analysis of the DART cohort

BACKGROUND

Donor-derived cell-free DNA (dd-cfDNA) is a marker of allograft injury in transplant recipients; however, the relationship between dd-cfDNA and other clinical parameters associated with adverse allograft outcomes is not well-characterized.

METHODS

We performed a retrospective analysis of kidney transplant recipients from the DART cohort (ClinicalTrials.gov Identifier: NCT02424227) to evaluate the associations between eGFR decline, de novo donor-specific antibodies (dnDSA), and dd-cfDNA.

RESULTS

Both elevated dd-cfDNA (≥1%) and dd-cfDNA variability (≥.34%) in the first post-transplant year were associated with decline in eGFR ≥25% in the second year (21.4% vs. 4.1%, P = .005; 25% vs. 3.6%, P = .002, respectively). Compared to samples from DSA negative patients, samples from patients with concurrent de novo HLA DSAs had higher dd-cfDNA levels (P < .0001).

DISCUSSION

Abnormalities in dd-cfDNA levels are associated with clinical parameters commonly used as surrogate endpoints for adverse allograft outcomes, raising the possibility that molecular injury as characterized by dd-cfDNA could help identify patients at risk of these outcomes.

Evaluation of blocking mechanisms against immunological responses in patients with laryngeal carcinoma

The specific tumor-induced leukocyte inhibition factor (LIF) production in laryngeal cancer patients has been investigated before and after the removal of adherent cells in order to evaluate the existence of a suppressor activity; 20 patients served as subject. The LIF production, after challenging the lymphocytes with 3MKC1 autologous tumor extracts, was significant in 12 patients and showed a further significant increase after the removal of adherent cells. In 3 patients with no previous significant LIF production, there was a conversion to significance when the adherent cells were removed. The other patients did not show any significant variation. These data seem to suggest the existence of a suppressor activity exerted by adherent cells in laryngeal cancer patients on LIF production.

Specific Lif Production in Laryngeal Cancer Patients: Evidence of Suppressor Activity Exerted by Adherent Cells

The specific tumor-induced LIF production in 30 laryngeal cancer patients has been investigated before and after the removal of adherent cells to evaluate the existence of a suppressor activity. LIF production, after challenging lymphocytes with 3 M KCl autologous tumor extracts, was significant in 16 patients and showed a further significant increase after removal of adherent cells. A conversion to significance when the adherent cells were removed was shown in 6 patients, with no previous significant LIF production. These data suggest the existence of a suppressor activity exerted by adherent cells on LIF production in laryngeal cancer patients.

Transient versus persistent BK viremia and long-term outcomes after kidney and kidney-pancreas transplantation

BACKGROUND AND OBJECTIVES

The objective was to study the long-term impact of transient versus persistent BK viremia on kidney transplant outcomes.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

In total, 609 recipients who underwent kidney transplant from 2007 to 2011 were screened at months 1-12 for the occurrence of polyomavirus BK viremia; 130 patients (21.7%) developed BK viremia during the first year post-transplant. BK viremia patients were classified according to duration of infection (more or less than 3 months), and BK viral loads (more or less than 10,000 copies/ml) were classified as transient low viremia (n=42), transient high viremia (n=18), persistent low viremia (n=23), and persistent high viremia (n=47). All patients were followed a median of 36 (3-66) months. The rates of BK polyomavirus-associated nephropathy, acute rejection, and 1-year graft function were compared with the polyomavirus BK-negative control group.

RESULTS

Patient and graft survival were not significantly different among the groups. Graft function (creatinine; milligrams per deciliter) at 1 year was significantly worse in the persistent high viremia (1.75±0.6) and transient high viremia (1.85±0.7) groups compared with aviremic controls (1.47±0.4; P=0.01 and P=0.01, respectively). The incidence of BK polyomavirus-associated nephropathy was limited to the persistent high viremia group (1.3%, P<0.001). The transient high viremia (50%) and persistent high viremia (34%) groups showed significantly (P=0.01) increased incidence of acute rejection versus aviremic controls (21.5%), transient low viremia (19%), or persistent low viremia (17.3%) groups.

CONCLUSION

Low viral load BK viremia, either transient or persistent, was not associated with long-term transplant outcomes. Persistent high viremia was associated with a greater risk for BK polyomavirus-associated nephropathy and subsequent graft dysfunction. Although transient high viremia was not associated with BK polyomavirus-associated nephropathy, it was associated with worse graft function. These data support the role of surveillance for BK viremia after transplant.

T cells reconstituting the periphery in thymoglobulin treated kidney transplant recipients are preferentially donor-senescent when compared to basiliximab treated patients (141.25)

Induction with anti-thymocyte globulin (ATG) results in better 1 yr renal transplant outcomes than basiliximab in immunologically sensitized transplant patients. This observation contrasts with the potential homeostatic proliferation of surviving donor-reactive T cells in the post-ATG lymphopenic environment. Donor-specific reactivity was measured longitudinally in 8 (n=4 for basiliximab, n=4 for ATG) kidney transplant recipients who completed a 6 mo follow-up. Peripheral blood cells at pretransplant and monthly posttransplant were tested for donor-reactivity by IFN-γ ELISPOT assays. Patients induced with ATG or basiliximab had similar decreases in their absolute lymphocyte counts (and total T cells) at 1 wk post-tx. While these counts returned to near baseline by 3 mo in basiliximab treated patients, counts in ATG-treated patients were 61% of baseline at 6 mo. Mean post-tx donor-specific alloreactive T cell frequencies at 6 mo follow-up were similar to pretransplant levels for basiliximab patients but were &lt;20% of pretransplant levels for ATG-treated patients. Furthermore, peripheral T cells in ATG-treated patients are not preferentially reconstituted with RO+ memory cells as might be expected in an environment promoting homeostatic proliferation. These data suggest that reconstitution of the periphery in ATG-treated patients is not preferentially donor-reactive.