Hege Pihlstrøm

Long-term risks for kidney donors

Previous studies have suggested that living kidney donors maintain long-term renal function and experience no increase in cardiovascular or all-cause mortality. However, most analyses have included control groups less healthy than the living donor population and have had relatively short follow-up periods. Here we compared long-term renal function and cardiovascular and all-cause mortality in living kidney donors compared with a control group of individuals who would have been eligible for donation. All-cause mortality, cardiovascular mortality, and end-stage renal disease (ESRD) was identified in 1901 individuals who donated a kidney during 1963 through 2007 with a median follow-up of 15.1 years. A control group of 32,621 potentially eligible kidney donors was selected, with a median follow-up of 24.9 years. Hazard ratio for all-cause death was significantly increased to 1.30 (95% confidence interval 1.11-1.52) for donors compared with controls. There was a significant corresponding increase in cardiovascular death to 1.40 (1.03-1.91), while the risk of ESRD was greatly and significantly increased to 11.38 (4.37-29.6). The overall incidence of ESRD among donors was 302 cases per million and might have been influenced by hereditary factors. Immunological renal disease was the cause of ESRD in the donors. Thus, kidney donors are at increased long-term risk for ESRD, cardiovascular, and all-cause mortality compared with a control group of non-donors who would have been eligible for donation.

Increased risk of all-cause mortality and renal graft loss in stable renal transplant recipients with hyperparathyroidism.

Background Hyperparathyroidism is reported in 10% to 66% of renal transplant recipients (RTR). The influence of persisting hyperparathyroidism on long-term clinical outcomes in RTR has not been examined in a large prospective study. Methods We investigated the association between baseline parathyroid hormone (PTH) levels and major cardiovascular events, renal graft loss, and all-cause mortality by Cox Proportional Hazard survival analyses in 1840 stable RTR derived from the Assessment of LEscol in Renal Transplantation trial. Patients were recruited in a mean of 5.1 years after transplantation, and follow-up time was 6 to 7 years. Results Significant associations between PTH and all 3 outcomes were found in univariate analyses. When adjusting for a range of plausible confounders, including measures of renal function and serum mineral levels, PTH remained significantly associated with all-cause mortality (4% increased risk per 10 units; P = 0.004), and with graft loss (6% increased risk per 10 units; P < 0.001), but not with major cardiovascular events. Parathyroid hormone above the upper limit of normal (65 pg/mL) indicated a 46% (P = 0.006) higher risk of death and an 85% higher risk of graft loss (P < 0.001) compared with low/normal values. Conclusions Hyperparathyroidism is an independent, potentially remediable, risk factor for renal graft loss and all-cause mortality in RTR.

Aortic Stiffness in a Mortality Risk Calculator for Kidney Transplant Recipients.

Background The association between aortic stiffness and all-cause mortality in kidney transplant recipients (KTRs) is uncertain, and aortic stiffness has not yet been incorporated into risk prediction tools. Methods During 2007 to 2012, we measured carotid-femoral pulse wave velocity (PWV; SphygmoCor apparatus) 8 weeks after transplantation. The association between PWV and mortality was assessed in a Cox regression analysis adjusting for seven risk factors from a previously validated model. Internal validation was performed by bootstrap resampling, and discrimination and overfitting evaluated by Harrell’s C and the calibration slope. Results Of 1497 KTRs, 1040 (69%) had a valid PWV measurement. During a median follow-up of 4.2 years, 82 patients died. The association between PWV and mortality showed a ceiling effect, and PWV was truncated at 12 m/sec. Each 1 m/sec increase in PWV, up to 12 m/sec, was associated with mortality, hazard ratio (HR) 1.36 (95% CI, 1.14-1.62; P = 0.001). An interquartile range increase (3.8 m/sec) tripled the hazard of mortality, HR, 3.21 (95% CI, 1.63-6.31), similar to the effect of being approximately 20 years older (interquartile range increase (21.6 years); HR, 3.06 [95% CI, 1.87-5.29]). The PWV improved model discrimination with an increase in Harrell’s C from 0.76 to 0.78; C difference, 0.024 (95% CI, 0.005-0.043; P = 0.01). Overfitting was moderate with a calibration slope of 0.89, and the final model was adjusted accordingly. A spreadsheet version is presented to estimate expected 5-year survival. Conclusions The PWV is a strong risk factor for mortality in KTRs.

Single Nucleotide Polymorphisms and Long-Term Clinical Outcome in Renal Transplant Patients: A Validation Study.

Genome‐wide association studies (GWAS) are designed to investigate single nucleotide polymorphisms (SNPs) and the association with a clinical phenotype. A previous GWAS performed in 300 renal transplant recipients identified two SNPs (rs3811321 and rs6565887) associated with serum creatinine and clinical outcome. We sought to validate these findings. Genotyping of the two SNPs was performed using Taqman assays in 1638 Caucasians participating in the Assessment of LEscol in Renal Transplant (ALERT) study. Primary endpoint was death‐censored graft loss, and secondary endpoint was all‐cause mortality. Applying Cox regression, no crude association to graft loss was found for rs3811321 on chromosome 14 (hazard ratio [HR] 0.87, 95% CI 0.59–1.29, p = 0.50) or rs6565887 on chromosome 18 (HR 0.88, CI 0.62–1.25, p = 0.48). Multivariable adjustments did not change results, nor did evaluation of the number of risk alleles formed by the two SNPs. No association with mortality was detected. In conclusion, an impact of two SNPs on chromosomes 14 and 18 on death‐censored graft survival or all‐cause mortality was not confirmed. Our results emphasize the importance of validating findings from high‐throughput genetics studies and call for large collaborative research initiatives in the field of transplantation outcomes.

Homoarginine and Clinical Outcomes in Renal Transplant Recipients: Results From the Assessment of Lescol in Renal Transplantation Study

Background Despite improvements in kidney transplantation, complications, including cardiovascular morbidity and graft loss, contribute to reduced graft and patient survival. The amino acid homoarginine exerts a variety of beneficial effects that may be relevant for cardiovascular and graft outcomes, which is investigated in the present study. Methods Homoarginine was measured in 829 renal transplant recipients participating in the placebo group of the Assessment of Lescol in Renal Transplantation study. Mean follow-up was 6.7 years. By Cox regression analyses, we determined hazard ratios (HRs) to reach prespecified, adjudicated endpoints according to baseline homoarginine levels: major adverse cardiovascular events (n = 103), cerebrovascular events (n = 53), graft failure or doubling of serum creatinine (n = 140), noncardiovascular mortality (n = 51), and all-cause mortality (n = 107). Results Patients mean age was 50 ± 11 years, homoarginine concentration was 1.96 ± 0.76 &mgr;mol/L, and 65% were men. Patients in the lowest homoarginine quartile (<1.40 &mgr;mol/L) had an adjusted 2.6-fold higher risk of cerebrovascular events compared to those in the highest quartile (>2.34 &mgr;mol/L) (HR, 2.56; 95% confidence interval [95% CI], 1.13–5.82). Similarly, the renal endpoint occurred at a significantly increased rate in the lowest homoarginine quartile (HR, 2.34; 95% CI, 1.36–4.02). For noncardiovascular and all-cause mortality, there was also increased risk associated with the lowest levels of homoarginine, with HRs of 4.34 (95% CI, 1.63–10.69) and 2.50 (95% CI, 1.38–4.55), respectively. Conclusions Low homoarginine is strongly associated with cerebrovascular events, graft loss and progression of kidney failure and mortality in renal transplant recipients. Whether interventions with homoarginine supplementation improve clinical outcomes requires further evaluation.

Association Between Pretransplant Cancer and Survival in Kidney Transplant Recipients

Background Kidney transplantation in recipients with a previous malignancy is often deferred 2 to 5 years after cancer treatment due to fear of cancer recurrence. In Norway, the required waiting period has been 1 year. Methods We compared patient and graft survival of recipients with pretransplant cancer to the outcomes of matched recipients without such cancer (comparators) using Cox regression. Results From 1963 to 2010, 377 (6.4%) of 5867 recipients had a pretransplant cancer. During a median follow-up of 6.8 years, 256 recipients died, 35 (13.7%) from recurrent cancer and 27 (10.5%) from de novo cancer. Uncensored and death-censored graft loss occurred in 263 and 46 recipients, respectively. All-cause mortality was similar as in comparators (hazard ratio [HR], 1.06; 95% confidence interval [CI], 0.93-1.20]; P = 0.40), death-censored graft loss was lower (HR, 0.63; 95% CI, 0.47-0.84; P = 0.002), and uncensored graft loss was similar (HR, 0.99; 95% CI, 0.87-1.12; P = 0.87). Cancer mortality was higher than in comparators (HR, 1.97; 95% CI, 1.51-2.56; P < 0.001), particularly during the first 5 years of follow-up (HR, 3.44; 95% CI, 2.36-5.03; P < 0.01). Waiting period was not associated with recurrent cancer mortality or all-cause mortality (both P > 0.45). Results were similar within cancer subgroups, with most data in patients with a history of kidney cancer, prostate cancer, urothelial cancer, and skin squamous cell carcinoma. Conclusions Kidney transplant recipients with a pretransplant cancer had a similar overall patient and graft survival as recipients without such cancer. Cancer mortality was increased, particularly during the first 5 years after transplantation. A short waiting period was not associated with mortality.

Early introduction of oral paricalcitol in renal transplant recipients. An open-label randomized study

In stable renal transplant recipients with hyperparathyroidism, previous studies have indicated that vitamin D agonist treatment might have anti‐proteinuric effects. Animal studies indicate possible anti‐fibrotic and anti‐inflammatory effects. Early introduction of paricalcitol in de novo renal transplant recipients might reduce proteinuria and prevent progressive allograft fibrosis. We performed a single‐center, prospective, randomized, open‐label trial investigating effects of paricalcitol 2 μg/day added to standard care. Participants were included 8 weeks after engraftment and followed for 44 weeks. Primary end point was change in spot urine albumin/creatinine ratio. Exploratory microarray analyses of kidney biopsies at study end investigated potential effects on gene expression. Secondary end points included change in glomerular filtration rate (GFR), pulse wave velocity (PWV), and endothelial function measured by peripheral arterial tonometry as reactive hyperemia index (RHI). Seventy‐seven de novo transplanted kidney allograft recipients were included, 37 receiving paricalcitol. Paricalcitol treatment lowered PTH levels (P = 0.01) but did not significantly reduce albuminuria (P = 0.76), change vascular parameters (PWV; P = 0.98, RHI; P = 0.33), or influence GFR (P = 0.57). Allograft gene expression was not influenced. To summarize, in newly transplanted renal allograft recipients, paricalcitol reduced PTH and was well tolerated without negatively affecting kidney function. Paricalcitol did not significantly reduce/prevent albuminuria, improve parameters of vascular health, or influence allograft gene expression.

Neopterin is associated with cardiovascular events and all-cause mortality in renal transplant patients

Inflammatory markers show significant associations with cardiovascular events and all‐cause mortality after kidney transplantation. Neopterin, reflecting interferon‐γ‐release, may better reflect the proinflammatory state of recipients than less specific markers.

Symmetric Dimethylarginine as Predictor of Graft loss and All-Cause Mortality in Renal Transplant Recipients

Background Elevated symmetric dimethylarginine (SDMA) has been shown to predict cardiovascular events and all cause mortality in diverse populations. The potential role of SDMA as a risk marker in renal transplant recipients (RTR) has not been investigated. Methods We analyzed SDMA in the placebo arm of the Assessment of Lescol in Renal Transplantation study, a randomized controlled trial of fluvastatin in RTR. Mean follow-up was 5.1 years. Patients were grouped into quartiles based on SDMA levels at study inclusion. Relationships between SDMA and traditional risk factors for graft function and all-cause mortality were analyzed in 925 RTR using univariate and multivariate survival analyses. Results In univariate analysis, SDMA was significantly associated with renal graft loss, all-cause death, and major cardiovascular events. After adjustment for established risk factors including estimated glomerular filtration rate, an elevated SDMA-level (4th quartile, >1.38 &mgr;mol/L) was associated with renal graft loss; hazard ratio (HR), 5.51; 95% confidence interval (CI), 1.95–15.57; P=0.001, compared to the 1st quartile. Similarly, SDMA in the 4th quartile was independently associated with all-cause mortality (HR, 4.56; 95% CI, 2.15–9.71; P<0.001), and there was a strong borderline significant trend for an association with cardiovascular mortality (HR, 2.86; 95% CI, 0.99–8.21; P=0.051). Conclusion In stable RTR, an elevated SDMA level is independently associated with increased risk of all-cause mortality and renal graft loss.

Uric acid and clinical correlates of endothelial function in kidney transplant recipients

Uric acid is associated with increased mortality in kidney transplant recipients (KTRs), but it is uncertain if this involves endothelial dysfunction. We hypothesized, first, that there was an association between uric acid and endothelial function, and second, that there were associations between endothelial function and cardiac and mortality risk scores.