Influence of C-Reactive Protein and Urinary Protein Excretion on Prediction of Graft Failure and Mortality by Serum Albumin in Renal Transplant Recipients

Cytomegalovirus Disease in Renal Transplanted Patients: Prevalence, Determining Factors, and Influence on Graft and Patients Outcomes

The prevalence and the factors related to cytomegalovirus (CMV) disease (CMVd) during the 1st year of renal transplantation (RTx) and the relationship between CMVd and early and long-term graft and RTx-patient (RTx-p) survival were evaluated. In 505 RTx-p, followed up for 8(5-11) years, data were recorded after 1-(T1) and 12-(T12) months of RTx. CMVd was defined either by CMV replication without clinical signs of disease (CMVr, 43%), or CMV replication with signs of disease (CMVs, 57%). During the 1st year of RTx, 45% of RTx-p had CMVd (CMVd+). CMVd+ patients were older than CMVd- patients. Female gender and Donor CMV-IgG+ (CMV IgG-D+)/recipient IgG- (CMV IgG-R-) status were more prevalent in CMVd+. At T1, CMVd+ had lower albumin, haemoglobin, and higher uric-acid and reactive C-protein than CMVd- and, at T1 and T12, received more steroids. Albumin-T1 was the unique factor in determining CMVd+, maintaining its significance also after the inclusion of IgG-D+/IgG-R- status to the model. CMVs had higher prevalence of CMV IgG-D+/IgG-R- than CMVr. CMVd, CMVr, and CMVs had no impact on graft loss (11% of RTx-p) and RTx-p death (8% of RTx-p). CMVd is highly prevalent during the 1st year of RTx. Albumin-T1 influences CMVd insurgence. CMVd did not impact on RTx and RTx-p loss.

Trans-fatty Acids and Survival in Renal Transplantation

OBJECTIVE

High consumption of trans-fatty acids (TFAs) is associated with increased mortality.

DESIGN AND METHODS

Observational cohort study of 1.988 Norwegian renal transplant recipients with a median follow-up time of 9.6 years. We assessed multivariable adjusted associations between plasma levels of industrial and ruminant TFAs with patient and graft survival. Plasma phospholipid fatty acid levels were determined by gas chromatography at 10 weeks after transplantation.

RESULTS

During follow-up, there were 595 deaths, and 805 grafts were lost. Plasma industrial TFA levels dropped from 0.3 wt% in years 1999-2004 to reach a plateau of 0.2 wt% from year 2005 and beyond, whereas plasma levels of ruminant TFAs remained stable throughout the study period. In the former era (years 1999 to 2004, n = 902), we found multivariable adjusted associations between plasma industrial TFA levels and mortality (hazard ratio 4.44, P = .02) and graft loss (hazard ratio 4.22, P = .01). In the latter era (years 2005 to 2011, n = 1,086), there were no associations between plasma industrial TFA levels and patient or graft survival. Plasma ruminant TFAs were not associated with mortality or graft loss in either eras.

CONCLUSION

In this Norwegian transplant cohort, plasma industrial TFA levels dropped from around 0.3 wt% in the former era to 0.2 wt% in the latter era. While plasma industrial TFA was significantly associated with survival in the former era, no associations were found with survival in the latter era. This finding suggests that lowering industrial TFA consumption from modest to low levels could possibly influence health beneficially after renal transplantation.

Association of Brain-Dead Donors' Terminal Inflammation With Delayed Graft Function in Kidney Transplant Recipients

BACKGROUND

Systemic inflammation affects kidney function in a wide range of diseases. Even in kidney transplant recipients, higher levels of C-reactive protein (CRP) are invariably associated with both worse short- and long-term graft outcomes. However, little is known about systemic inflammation in kidney donors and, notably, brain death causes a strong systemic inflammatory response.

OBJECTIVE

To analyze the role of systemic inflammation of brain-dead donors on short-term kidney graft outcomes (ie, delayed graft function [DGF], defined as the need of dialysis during the first week after transplantation).

MATERIALS AND METHODS

Retrospective analysis of clinical and biochemical characteristics of all brain-dead kidney donors generated in the Hospital Clínic of Barcelona in the 2006 to 2015 period (n = 194). Donors who were tested for CRP in the 24 hours before BD declaration were included (n = 97, 50% of initial population). Clinical and biochemical features of their respective recipients (n = 165) were analyzed, comparing recipients who developed DGF (n = 30) with recipients who did not (n = 135).

RESULTS

Donors whose recipients later developed DGF had much higher CRP values (10.58 [5.1-18.21] vs 4.81 [1.42-12.2] mg/dL, P = .025). Other characteristics associated with the development of DGF were renal biopsy score and recipient dialysis vintage (P = .025 and P = .002, respectively). In logistic regression analysis, PCR maintained significance in the non-expanded criteria donor (ECD) group (odds ratio [OR], 1.102; P = .027), but it lost significance in the ECD group (P = .67).

CONCLUSIONS

Terminal donor CRP was associated with DGF in kidney transplant recipients and proved to be mostly significant in younger donors.

The tryptophan/kynurenine pathway, systemic inflammation, and long-term outcome after kidney transplantation

Tryptophan is metabolized along the kynurenine pathway, initially to kynurenine, and subsequently to cytotoxic 3-hydroxykynurenine. There is increasing interest in this pathway because of its proinflammatory nature, and drugs interfering in it have received increasing attention. We aimed to investigate whether serum and urinary parameters of the tryptophan/kynurenine pathway, and particularly cytotoxic 3-hydroxykynurenine, are associated with systemic inflammation and long-term outcome in renal transplant recipients (RTR). Data were collected in outpatient RTR with a functioning graft for >1 yr. Tryptophan, kynurenine, and 3-hydroxykynurenine in serum and urine were measured using LC-MS/MS. A total of 561 RTR (age: 51 ± 12 yr; 56% male) were included at a median of 6.0 (2.6-11.6) yr posttransplantation. Baseline median serum tryptophan was 40.0 (34.5-46.0) µmol/l, serum kynurenine was 1.8 (1.4-2.2) µmol/l, and serum 3-hydroxykynurenine was 42.2 (31.0-61.7) nmol/l. Serum kynurenine and 3-hydroxykynurenine were strongly associated with parameters of systemic inflammation. During follow-up for 7.0 (6.2-7.5) yr, 51 RTR (9%) developed graft failure and 120 RTR (21%) died. Both serum kynurenine and 3-hydroxykynurenine were independently associated with graft failure [HR 1.72 (1.23-2.41), P = 0.002; and HR 2.03 (1.42-2.90), P < 0.001]. Serum 3-hydroxykynurenine was also independently associated with mortality [HR 1.37 (1.08-1.73), P = 0.01], whereas serum kynurenine was not. Urinary tryptophan/kynurenine pathway parameters were not associated with outcome. Of tryptophan metabolites, serum 3-hydroxykynurenine is cross-sectionally most strongly and consistently associated with systemic inflammation and prospectively with adverse long-term outcome after kidney transplantation. Serum 3-hydroxykynurenine may be an interesting biomarker and target for the evaluation of drugs interfering in the tryptophan/kynurenine pathway.

Creatinine-Based and Cystatin C-Based GFR Estimating Equations and Their Non-GFR Determinants in Kidney Transplant Recipients

BACKGROUND AND OBJECTIVES

eGFR equations have been evaluated in kidney transplant recipients with variable performance. We assessed the performance of the Modification of Diet in Renal Disease equation and the Chronic Kidney Disease Epidemiology Collaboration equations on the basis of creatinine, cystatin C, and both (eGFR creatinine-cystatin C) compared with measured GFR by iothalamate clearance and evaluated their non-GFR determinants and associations across 15 cardiovascular risk factors.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

A cross-sectional cohort of 1139 kidney transplant recipients >1 year after transplant was analyzed. eGFR bias, precision, and accuracy (percentage of estimates within 30% of measured GFR) were assessed. Interaction of each cardiovascular risk factor with eGFR relative to measured GFR was determined.

RESULTS

Median measured GFR was 55.0 ml/min per 1.73 m(2). eGFR creatinine overestimated measured GFR by 3.1% (percentage of estimates within 30% of measured GFR of 80.4%), and eGFR Modification of Diet in Renal Disease underestimated measured GFR by 2.2% (percentage of estimates within 30% of measured GFR of 80.4%). eGFR cystatin C underestimated measured GFR by -13.7% (percentage of estimates within 30% of measured GFR of 77.1%), and eGFR creatinine-cystatin C underestimated measured GFR by -8.1% (percentage of estimates within 30% of measured GFR of 86.5%). Lower measured GFR associated with older age, women, obesity, longer time after transplant, lower HDL, lower hemoglobin, lower albumin, higher triglycerides, higher proteinuria, and an elevated cardiac troponin T level but did not associate with diabetes, smoking, cardiovascular events, pretransplant dialysis, or hemoglobin A1c. These risk factor associations differed for five risk factors with eGFR creatinine, six risk factors for eGFR Modification of Diet in Renal Disease, ten risk factors for eGFR cystatin C, and four risk factors for eGFR creatinine-cystatin C.

CONCLUSIONS

Thus, eGFR creatinine and eGFR creatinine-cystatin C are preferred over eGFR cystatin C in kidney transplant recipients because they are less biased, more accurate, and more consistently reflect the same risk factor associations seen with measured GFR.

Vitamin K status and mortality after kidney transplantation: a cohort study

BACKGROUND

Vitamin K modulates calcification by activating calcification inhibitors such as matrix Gla protein (MGP). In kidney transplant recipients, vitamin K insufficiency is common, but implications for long-term outcomes are unclear.

STUDY DESIGN

Single-center observational study with a longitudinal design.

SETTING & PARTICIPANTS

518 stable kidney transplant recipients; 56% men; mean age, 51±12 (SD) years; and a median of 6 (IQR, 3-12) years after kidney transplantation.

FACTOR

Plasma desphosphorylated-uncarboxylated MGP (dp-ucMGP) levels, reflecting vitamin K status.

OUTCOMES

All-cause mortality and transplant failure.

RESULTS

At inclusion, median dp-ucMGP level was 1,038 (IQR, 733-1,536) pmol/L, with 473 (91%) patients having vitamin K insufficiency (defined as dp-ucMGP>500pmol/L). During a median follow-up of 9.8 (IQR, 8.5-10.2) years, 152 (29%) patients died and 54 (10%) developed transplant failure. Patients in the highest quartile of dp-ucMGP were at considerably higher mortality risk compared with patients in the lowest quartile (HR, 3.10; 95% CI, 1.87-5.12; P for trend<0.001; P for quartile 1 [Q1] vs Q4<0.001). After adjustment for potential confounders, including kidney function and exclusion of patients treated with a vitamin K antagonist, this association remained significant. Patients in the highest quartile also were at higher risk of developing transplant failure (HR, 2.61; 95% CI, 1.22-5.57; P for trend=0.004; P for Q1 vs Q4=0.01), but this association was lost after adjustment for baseline kidney function (HR, 1.20; 95% CI, 0.52-2.75; P for trend=0.6; P for Q1 vs Q4=0.7).

LIMITATIONS

Although MGP exists as various species, only dp-ucMGP was measured. No data were available for vascular calcification as an intermediate end point.

CONCLUSIONS

Vitamin K insufficiency, that is, a high circulating level of dp-ucMGP, is highly prevalent in stable kidney transplant recipients and is associated independently with increased risk of mortality. Future studies should address whether vitamin K supplementation may lead to improved outcomes after kidney transplantation.

The impact of pretransplantation serum albumin levels on long-term renal graft outcomes

BACKGROUND

The association between pretransplantation serum albumin concentrations and renal graft outcomes is unclear. Hypoalbuminemia is a strong predictor of cardiovascular and all-cause mortality in chronic renal disease. Protein-energy wasting in dialysis patients is associated with irreversible damage and an increased risk of adverse outcomes. In this retrospective study, we investigated the association between preoperative albumin levels and short-term as well as long-term renal graft outcomes.

MATERIALS AND METHODS

We included 375 renal transplant recipients in our center between 1991 to 2011, who were grouped according to their preoperative serum albumin levels: group I (<3.5 g/dL), group II (3.5-3.9 g/dL), group III (4.0-4.4 g/dL), and group IV (≥ 4.5 g/dL). We measured the frequencies of delayed graft function (DGF), acute rejection episodes, and viral infections as well as the long-term graft outcomes.

RESULT

DGF affected 12.8%, 6.8%, 7.7%, and 9.3% of patients in groups I-IV, respectively. Acute rejection occurred in 27.7%, 27.2%, 31.6%, and 24.1%, while cytomegalovirus (CMV) and fungal infection occurred in 12.8% (6.4%), 23.3% (5.8%), 16.2% (2.6%), and 11.1% (5.6%) of patients, respectively. Serum creatinine levels at 12 months were not significantly different among the groups. Long-term graft survival was poorest in group I and best in group IV (P = .039). A Cox proportional hazards model showed group IV compared with group displayed the lowest relative risk of graft failure (hazard ratio [HR] = .536; P = .029).

CONCLUSIONS

Low pretransplantation serum albumin levels were associated with poor long-term graft outcomes and with more post-transplantation complications. It may be necessary to focus on improving patients' nutritional status prior to transplantation to ensure long-term renal graft survival.

Pretransplantation erythropoiesis-stimulating agent hyporesponsiveness is associated with increased kidney allograft failure and mortality

BACKGROUND

Poor response to erythropoiesis-stimulating agents (ESA) is associated with morbidity and mortality among dialysis patients. It is unclear whether the risk associated with poor ESA response during dialysis extends beyond kidney transplantation. We examined pretransplantation ESA response and its effect on allograft failure and mortality.

METHODS

The cohort included all adult Medicare recipients from the U.S. Renal Data System who had received a kidney transplant during years 2000 to 2007 and had at least 6 months of hemodialysis immediately before transplantation. ESA hyporesponsiveness was primarily defined as a monthly ESA dose of 75,000 units or higher and hematocrit 33% or less for at least 3 consecutive months in the pretransplantation period. Crude and adjusted Cox proportional hazards models and Kaplan-Meier methods were used to estimate the effect of ESA hyporesponsiveness on allograft failure and all-cause mortality.

RESULTS

The study group consisted of 36,450 patients; 1004 exhibited hyporesponsiveness. The adjusted hazard ratios (95% confidence interval) for allograft failure and mortality after transplantation were 1.23 (1.10-1.42) and 1.61 (1.43-1.81), respectively, supporting that poor ESA response during hemodialysis is associated with adverse posttransplantation outcomes.

CONCLUSIONS

ESA hyporesponsiveness may be useful in identifying potential allograft recipients who are at high risk for subsequent morbidity and mortality and may benefit from more intensive pretransplantation and posttransplantation monitoring.

Associations of pretransplant serum albumin with post-transplant outcomes in kidney transplant recipients

The association between pretransplant serum albumin concentration and post-transplant outcomes in kidney transplant recipients is unclear. We hypothesized that in transplant-waitlisted hemodialysis patients, lower serum albumin concentrations are associated with worse post-transplant outcomes. Linking the 5-year patient data of a large dialysis organization (DaVita) to the Scientific Registry of Transplant Recipients, we identified 8961 hemodialysis patients who underwent first kidney transplantation. Mortality or graft failure and delayed graft function (DGF) risks were estimated by Cox regression (hazard ratio [HR]) and logistic regression (Odds ratio [OR]), respectively. Patients were 48 ± 13 years old and included 37% women and 27% diabetics. The higher pretransplant serum albumin was associated with lower mortality, graft failure and DGF risk even after multivariate adjustment for case-mix, malnutrition-inflammation complex and transplant related variable. Every 0.2 g/dL higher pretransplant serum albumin concentration was associated with 13% lower all-cause mortality (HR = 0.87 [95% confidence interval: 0.82-0.93]), 17% lower cardiovascular mortality (HR = 0.83[0.74-0.93]), 7% lower combined risk of death or graft failure (HR = 0.93[0.89-0.97]) and 4% lower DGF risk (OR = 0.96[0.93-0.99]). Hence, lower pretransplant serum albumin level is associated with worse post-transplant outcomes. Clinical trials to examine interventions to improve nutritional status in transplant-waitlisted hemodialysis patients and their impacts on post-transplant outcomes are indicated.