Association of chronic kidney graft failure with recipient blood pressure. Collaborative Transplant Study

Office or home versus 24-h blood pressure measurement in stable kidney transplant recipients

BACKGROUND

The aim of this study was to quantify hypertension control and evaluate concordance between all commonly available blood pressure (BP) modalities in kidney transplant recipients (KTRs).

METHODS

For this prospective cross-sectional study, 89 stable KTRs were recruited at the Charité Transplant Outpatient Clinic. For each study participant office [manual office BP (MOBP) and automated office BP (AOBP)], 7-day home (HBPM) and 24-hour ambulatory BP (24h-ABPM) measurements were performed.

RESULTS

80 of the 89 patients recruited had sufficient BP recordings. The mean BP for MOBP, AOBP, HBPM and 24h-ABPM was 129/73, 126/71, 131/85 and 130/81 mmHg, respectively. Uncontrolled hypertension, as defined by 24h-ABPM (mean ≥130/80 mmHg), was present in 53 (66%) patients. MOBP, AOBP and HBPM classified 19 (24%), 22 (28%) and 41 (51%) patients, respectively, as 'uncontrolled hypertensive'. The Bland-Altman plot showed good agreement between systolic MOBP, AOBP, HBPM and daytime-ABPM (mean bias: -1 ± 13 mmHg, -4 ± 13 mmHg, 1 ± 10 mmHg, respectively). Uncontrolled night-time hypertension was present in 74 (93%) KTRs, with 71 (89%) patients showing a non-physiological dipping pattern. Moderate positive correlation between daytime-ABPM/HBPM and night-time-ABPM (Pearson correlation coefficients: 0.62-0.73), followed by MOBP/AOBP (Pearson correlation coefficients: 0.49-0.59) was noted. Estimated eGFR and proteinuria displayed weak correlation with 24h-, daytime- and night-time-ABPM (absolute values of Pearson correlation coefficients: 0.04-0.41). No robust association with either 24h-, daytime- or night-time-ABPM was observed for volume status exams.

CONCLUSIONS

Masked hypertension is highly prevalent in KTRs, especially due to high rates of uncontrolled night-time hypertension. HBPM shows the narrowest limits of agreement with daytime-ABPM. Daytime-ABPM and HBPM show the highest, albeit clinically insufficient, correlation with night-time-ABPM. Systematic integration of 24h-ABPM into clinical practice, as proposed by the 2023 ESH guidelines for the management of arterial hypertension, should not be withheld for the KTR population. Clinical trials evaluating the treatment of hypertension in KTRs are urgently needed.

Bridging the Gap Between CKD Management Paradigms in Transplant and Nontransplant Settings: Published Evidence, Challenges, and Perspectives

Kidney transplantation (KT) is the best treatment for patients with kidney failure, associated with improved survival and quality of life compared with maintenance dialysis. However, despite constant improvements in the assessment and management of the alloimmune response, KT patients frequently demonstrate a reduced estimated glomerular filtration rate. Therefore, the usual complications of chronic kidney disease (CKD), such as anemia, hypertension, metabolic acidosis, hyperkalemia, or persistent secondary hyperparathyroidism, are highly prevalent after KT. However, their underlying mechanisms are different in the transplant setting (compared with the nontransplanted CKD population), and management recommendations are based on relatively poor-quality data. In recent years, new therapies have emerged, significantly improving kidney and cardiovascular outcomes of non-KT patients with CKD. Whether those new drugs could improve the outcomes of KT patients has largely been under investigated so far. In this review, we will address the challenges of the management of a KT patient with a reduced estimated glomerular filtration rate, cover the published evidence, and highlight the critical knowledge gaps.

Impact of Blood Pressure on Allograft Function and Survival in Kidney Transplant Recipients

The optimal target blood pressure for kidney transplant (KT) patients remains unclear. We included 808 KT patients from the KNOW-KT as a discovery set, and 1,294 KT patients from the KOTRY as a validation set. The main exposures were baseline systolic blood pressure (SBP) at 1 year after KT and time-varying SBP. Patients were classified into five groups: SBP <110; 110-119; 120-129; 130-139; and ≥140 mmHg. SBP trajectories were classified into decreasing, stable, and increasing groups. Primary outcome was composite kidney outcome of ≥50% decrease in eGFR or death-censored graft loss. Compared with the 110-119 mmHg group, both the lowest (adjusted hazard ratio [aHR], 2.43) and the highest SBP (aHR, 2.25) were associated with a higher risk of composite kidney outcome. In time-varying model, also the lowest (aHR, 3.02) and the highest SBP (aHR, 3.60) were associated with a higher risk. In the trajectory model, an increasing SBP trajectory was associated with a higher risk than a stable SBP trajectory (aHR, 2.26). This associations were consistent in the validation set. In conclusion, SBP ≥140 mmHg and an increasing SBP trajectory were associated with a higher risk of allograft dysfunction and failure in KT patients.

Predicting kidney allograft survival with explainable machine learning

INTRODUCTION

Despite significant progress over the last decades in the survival of kidney allografts, several risk factors remain contributing to worsening kidney function or even loss of transplants. We aimed to evaluate a new machine learning method to identify these variables which may predict the early graft loss in kidney transplant patients and to assess their usefulness for improving clinical decisions.

MATERIAL AND METHODS

A retrospective cohort study was carried out with 627 kidney transplant patients followed at least three months. All these data were pre-processed, and their selected features were used to develop an automatically working a machine learning algorithm; this algorithm was then applied for training and parameterization of the model; and finally, the tested model was then used for the analysis of patients' features that were the most impactful for the prediction of clinical outcomes. Our models were evaluated using the Area Under the Curve (AUC), and the SHapley Additive exPlanations (SHAP) algorithm was used to interpret its predictions.

RESULTS

The final selected model achieved a precision of 0.81, a sensitivity of 0.61, a specificity of 0.89, and an AUC value of 0.84. In our model, serum creatinine levels of kidney transplant patients, evaluated at the hospital discharge, proved to be the most important factor in the decision-making for the allograft loss. Patients with a weight equivalent to a BMI closer to the normal range prior to a kidney transplant are less likely to experience graft loss compared to patients with a BMI below the normal range. The age of patients at transplantation and Polyomavirus (BKPyV) infection had significant impact on clinical outcomes in our model.

CONCLUSIONS

Our algorithm suggests that the main characteristics that impacted early allograft loss were serum creatinine levels at the hospital discharge, as well as the pre-transplant values such as body weight, age of patients, and their BKPyV infection. We propose that machine learning tools can be developed to effectively assist medical decision-making in kidney transplantation.

Current Evidence on Dietary Factors and Kidney Allograft Function in Kidney Transplant Recipients: A Systematic Review

BACKGROUND

Currently, there is no accounted-for consensus and practical standard when counseling diet modification for kidney transplant recipients (KTRs). There are many differences between transplant centers regarding what KTRs are needed to follow a diet, what dietary factors and supplements are allowed, and how long KTRs should follow a modified diet. Relatively few scatter data are available for dietary factors in KTRs. Thus, we aimed to systematically review the literature on the purported dietary factors for kidney function.

METHODS

A systematic literature search was performed between February and March 2022 and updated in February 2023 using PubMed, Scopus, Web of Science, and Google Scholar. We included human observational and interventional studies that evaluated a dietary factor on kidney function and graft survival in KTRs. Data were extracted, and the risk of bias was assessed using established tools relevant to the study design.

RESULTS

Of the 5341 citations retrieved, seven prospective cohorts, five cross-sectional, seventeen randomized, and ten non-randomized clinical trials were included that evaluated seven purported dietary factors. Almost half of the studies (n = 22; 56%) were classified as having a low degree of bias and sufficient support. Twenty-one studies (54%) reported a positive effect on KTRs. DASH and Mediterranean diets decreased graft failure, low-sodium diet reduced blood pressure, and antioxidants improved creatinine, GFR, and graft function. Of these, only twelve studies (31%) were at low risk of bias.

CONCLUSION

Some dietary factors, including DASH, Mediterranean, moderate protein, and low-- sodium diet, as well as antioxidants, may be associated with improved survival and kidney function in KTRs. However, more research is needed.

The impact of diabetes and hypertension on renal allograft survival- A single center study

Background

To determine the impact of pre-transplant diabetes mellitus (DM) and post-transplant hypertension (HT) at 1 year on renal allograft survival in all adult first kidney-only (FKO) transplant recipients at a single transplant center in Johannesburg, South Africa.

Materials and methods

A retrospective review was conducted of all adult FKO transplant procedures at the Charlotte Maxeke Johannesburg Academic Hospital transplant unit between 1966 and 2013.

Results

During the stipulated timeframe, 1685 adult FKO transplant procedures were performed. Of these, 84.1% were from deceased donors (n = 1413/1685). The prevalence of pre-transplant DM transplant recipients with no missing or incomplete records was 6.5% (n = 107/1625). Of the total cohort of 1685 adult FKO transplant recipients, 63.6% of those with no missing data survived to 1 year (n = 1072/1685). The prevalence of HT at 1-year post-transplant was 53.6% (n = 503/1072). HT at 1-year post-transplant, even after adjusted survival analysis, proved a significant risk factor for renal allograft loss (hazard ratio, 1.63; 95% confidence interval, 1.37-1.94) (p < 0.0001). Similarly, after adjusted survival analysis, the risk of renal allograft loss within the pre-transplant DM group was significantly higher (p = 0.043; hazard ratio, 1.26; 95% confidence interval, 1.01-1.58).

Conclusions

This study identified pre-transplantation diabetes mellitus and post-transplantation HT as significant risk factors for graft loss within the population assessed in this region of the world. These factors could potentially be used as independent predictors of renal graft survival.

The Blocking of Drug Resistance Channels by Selected Hydrophobic Statins in Chemoresistance Human Melanoma

Despite the development of modern drugs, drug resistance in oncology remains the main factor limiting the curability of patients. This paper shows the use of a group of hydrophobic statins to inhibit drug resistance (Pgp protein). In a chemoresistance melanoma cell model, viability, necroptosis with DNA damage, the absorption of the applied pharmaceuticals, and the functional activity of the ABCB1 drug transporter after administration of docetaxel or docetaxel with a selected hydrophobic statin were studied. Taxol-resistant human melanoma cells from three stages of development were used as a model: both A375P and WM239A metastatic lines and radial growth phase WM35 cells. An animal model (Mus musculus SCID) was developed for the A375P cell line. The results show that hydrophobic statins administered with docetaxel increase the accumulation of the drug in the tumor cell a.o. by blocking the ABCB1 channel. They reduce taxol-induced drug resistance. The tumor size reduction was observed after the drug combination was administrated. It was shown that the structural similarity of statins is of secondary importance, e.g., pravastatin and simvastatin. Using cytostatics in the presence of hydrophobic statins increases their effectiveness while reducing their overall toxicity.

Amiloride evokes significant natriuresis and weight loss in kidney transplant recipients with and without albuminuria

Albuminuria in kidney transplant recipients (KTRs) is associated with hypertension and aberrant glomerular filtration of serine proteases that may proteolytically activate the epithelial Na+ channel (ENaC). The present nonrandomized, pharmacodynamic intervention study aimed to investigate if inhibition of ENaC increases Na+ excretion and reduces extracellular volume in KTRs dependent on the presence of albuminuria. KTRs with and without albuminuria (albumin-to-creatinine ratio > 300 mg/g, n = 7, and <30 mg/g, n = 7, respectively) were included and ingested a diet with fixed Na+ content (150 mmol/day) for 5 days. On the last day, amiloride at 10 mg was administered twice. Body weight, 24-h urine electrolyte excretion, body water content, and ambulatory blood pressure as well as plasma renin, angiotensin II, and aldosterone concentrations were determined before and after amiloride. Amiloride led to a significant decrease in body weight, increase in 24-h urinary Na+ excretion, and decrease in 24-h urinary K+ excretion in both groups. Urine output increased in the nonalbuminuric group only. There was no change in plasma renin, aldosterone, and angiotensin II concentrations after amiloride, whereas a significant decrease in nocturnal systolic blood pressure and increase in 24-h urine aldosterone excretion was observed in albuminuric KTRs only. There was a significant correlation between 24-h urinary albumin excretion and amiloride-induced 24-h urinary Na+ excretion. In conclusion, ENaC activity contributes to Na+ and water retention in KTRs with and without albuminuria. ENaC is a relevant pharmacological target in KTRs; however, larger and long-term studies are needed to evaluate whether the magnitude of this effect depends on the presence of albuminuria.NEW & NOTEWORTHY Amiloride has a significant natriuretic effect in kidney transplant recipients (KTRs) that relates to urinary albumin excretion. The epithelial Na+ channel may be a relevant direct pharmacological target to counter Na+ retention and hypertension in KTRs. Epithelial Na+ channel blockers should be further investigated as a mean to mitigate Na+ and water retention and to potentially obtain optimal blood pressure control in KTRs.

Uncontrolled hypertension is associated with increased risk of graft failure in kidney transplant recipients: a nationwide population-based study

Backgroud

Hypertension is highly prevalent in patients with kidney transplantation caused by transplantation-related immunologic or non-immunologic risk factors. However, whether a strict definition of hypertension (≥130/80 mmHg) and subdivided blood pressure (BP) groups are associated with an increased risk of graft failure after kidney transplantation using a nationwide large cohort study are still unknown.

Methods

Using Korean National Health Insurance Service data, we included 14,249 patients who underwent kidney transplantation from 2002 to 2016. Patients were categorized into five BP groups according to the 2021 Kidney Disease: Improving Global Outcomes practice guidelines for BP management: normal BP (<120/80 mmHg), elevated BP (120-129/ < 80 mmHg), incident hypertension (≥130/80 mmHg), and controlled or uncontrolled hypertension with anti-hypertensive medications.

Results

The primary outcome was graft failure, which occurred in 1934 (13.6%) participants during the 6-year follow-up. After adjusting for covariates, hypertension was associated with a higher risk of graft failure [Adjusted hazard ratio (AHR), 1.70; 95% confidence interval (CI), 1.48-1.96)] than no-hypertension. The AHR for graft failure was the highest in patients with uncontrolled hypertension (AHR, 2.13; 95% CI, 1.80-2.52). The risk of graft failure had a linear relationship with systolic and diastolic BP, and pulse pressure.

Conclusions

In this nationwide population-based study, hypertension ≥130/80 mmHg based on the 2021 KDIGO BP guidelines in kidney transplantion recipients, and elevated systolic and diastolic BP, and pulse pressure were associated with the risk of developing graft failure in kidney transplant recipients.

Incidence and Factors Associated with Uncontrolled Hypertension at 12 months after Kidney Transplantation in Saudi Arabia

INTRODUCTION

Uncontrolled blood pressure (uBP) after kidney transplantation (KTx) is very common and is associated with significant morbidity. However, studies that assess its incidence and risk factors are limited and outdated in the Middle East.

METHODS

This is a single-center retrospective study of KTx recipients (KTRs) in our center between January 2017 and May 2020 with a 12-month follow-up period. The target of hypertension treatment during the time of this study was <140/90 mm Hg, according to the published guidelines. We divided patients according to their blood pressure (BP) control at 1 year into two groups: controlled BP (cBP) (<140/90) and uBP (≥140/90). We studied the association between uBP and patients' demographics, baseline cardiovascular risk factors, and changes in their metabolic and cardiovascular profile during the first 12 months post-KTx.

RESULTS

A total of 254 KTRs were included. 79.2% developed post-KTx hypertension, 74% were ≥30 years, 58% were men, and 80% were living donor KTRs. The renal replacement modality among our patients pre-KTx was hemodialysis in 78.4%, peritoneal dialysis in 11.5%, and 10.1% underwent preemptive transplantation. At 1 year, 76 (29.9%) KTRs did not attain the target BP goal. Systolic BP (SBP) decreased from baseline to 12 months by 13 ± 24 mm Hg in the cBP group and increased by 8.7 ± 21 mm Hg in the uBP group (p < 0.001). Additionally, diastolic BP (DBP) decreased by 8.5 ± 16.9 mm Hg in the cBP group and increased by 2.3 ± 18.8 mm Hg in the uBP group (p < 0.001). Factors associated with uBP included age (47 vs. 41 years, p = 0.008) and diabetes mellitus (p = 0.012). Contrarily, gender, dialysis vintage, preemptive transplantation, type of dialysis (hemodialysis vs. peritoneal dialysis), type of transplant (living donor KTx vs. deceased donor KTx), and smoking were not different among the two groups. There were no significant differences between the two groups in regard to changes in creatinine, weight, A1c, low-density lipoprotein, and parathyroid hormone levels. Additionally, rate of rejection, new onset diabetes post-transplant, and persistent hyperthyroidism were not different between the groups. However, higher body mass index at 12 months was associated with a higher incidence of uBP (27.2 ± 5.9 vs. 29.2 ± 5.4, p = 0.013). Using multivariate analysis, we found that serum creatinine at 12 months was the only predictor of uBP (OR = 1.005 [1-1.011], p = 0.036).

CONCLUSION

At 1-year post-renal transplantation, about one-third of KTRs had uBP despite multiple antihypertensive medications. SBP and DBP significantly trended upward after transplantation in uBP patients, whereas SBP and DBP significantly trended downward after transplantation in cBP patients. Serum creatinine at 12 months was the only factor independently associated with uBP.

Usefulness of Dietary Salt Restriction in Kidney Transplant Recipients: Analysis of Blood Pressure Levels Depending on the Differences in the Levels of Salt Intake

BACKGROUND

Sodium retention causes post-transplant hypertension, and sodium restriction is recommended in kidney transplantation recipients. We investigated the changes in salt intake and age-specific differences in salt intake over the post-transplant periods and considered what guidance is important for salt reduction tailored to individual recipients.

METHODS

We calculated salt intake for 38 recipients who underwent kidney transplantation from August 2013 to August 2018 using Tanaka's equation and extracted their blood pressure (BP) levels.

RESULTS

The rate of achieving the desired level of salt intake (<6 g/d) was 7.9%. The average salt intake was 7.8 ± 1.4 g. Average BP by salt intake was as follows: <6 g/d, 109/71 mm Hg; 6 to <7 g/d, 127/84 mm Hg; 7 to <8 g/d, 124/79 mm Hg, 8 to <9 g/d, 130/73 mm Hg; 9 to <10 g/d, 133/83 mm Hg; and >10g/d, 137/81 mm Hg.

DISCUSSION

Awareness of the need for salt restriction diminishes as time passes after transplantations, leading to increased salt uptake; therefore, regular guidance for keeping salt intake low is necessary for patients to maintain the awareness of salt restriction. The recipients with higher salt intake had higher blood pressure, suggesting the need for managing salt reduction.

CONCLUSIONS

Dietary counseling showed a short-term efficacy for reducing sodium intake and clinically relevant BP improvement in renal allograft recipients.

Deep venous thrombosis in a kidney transplant recipient with COVID-19: a case report

The outcomes of COVID-19 in kidney transplant recipients have shown high mortality. In addition to their immunocompromised states, kidney transplant recipients frequently have certain exacerbation risk comorbidities of COVID-19, such as diabetes mellitus, hypertension, and chronic kidney disease. Several concomitant diseases develop during the course of COVID-19, one of which is thromboembolism, which can potentially lead to a critical condition. However, thromboembolic complications in kidney transplant recipients with COVID-19 have not been fully addressed in previous studies. A 62-year-old man, who underwent kidney transplantation 17 years ago, was diagnosed with COVID-19 and was admitted to our hospital. Although the patient was in remission at the start of the hospitalization, his condition became severe on day 7 after admission, with fever, elevated white blood cell counts (10,000/μL) and a high C-reactive protein level (6.9 mg/dL). Although the patient was not under forced bed rest, an ultrasound study on day 10 detected deep venous thrombosis (DVT), with an elevated D-dimer level (6.2 µg/dL). We withdrew the mycophenolate mofetyl and the tacrolimus dosage but did not administer any specific treatment for COVID-19. The patient achieved successful clearance of SARS-CoV-2 on day 16. The DVT disappeared after systematic heparin treatment and oral rivaroxaban for 2 months. DVT occurred in a kidney transplant recipient with COVID-19 who was not bedridden and might manifest when the clinical status was exacerbated during hospitalization.

Hypertension in kidney transplant recipients

Kidney transplantation is considered the treatment of choice for end-stage kidney disease patients. However, the residual cardiovascular risk remains significantly higher in kidney transplant recipients (KTRs) than in the general population. Hypertension is highly prevalent in KTRs and represents a major modifiable risk factor associated with adverse cardiovascular outcomes and reduced patient and graft survival. Proper definition of hypertension and recognition of special phenotypes and abnormal diurnal blood pressure (BP) patterns is crucial for adequate BP control. Misclassification by office BP is commonly encountered in these patients, and a high proportion of masked and uncontrolled hypertension, as well as of white-coat hypertension, has been revealed in these patients with the use of ambulatory BP monitoring. The pathophysiology of hypertension in KTRs is multifactorial, involving traditional risk factors, factors related to chronic kidney disease and factors related to the transplantation procedure. In the absence of evidence from large-scale randomized controlled trials in this population, BP targets for hypertension management in KTR have been extrapolated from chronic kidney disease populations. The most recent Kidney Disease Improving Global Outcomes 2021 guidelines recommend lowering BP to less than 130/80 mmHg using standardized BP office measurements. Dihydropyridine calcium channel blockers and angiotensin-converting enzyme inhibitors/angiotensin-II receptor blockers have been established as the preferred first-line agents, on the basis of emphasis placed on their favorable outcomes on graft survival. The aim of this review is to provide previous and recent evidence on prevalence, accurate diagnosis, pathophysiology and treatment of hypertension in KTRs.

Morning blood pressure surge in renal transplant recipients: Its relation to graft function and arterial stiffness

BACKGROUND

When the blood pressure rises before awakening in the morning, it is called as morning blood pressure pulse (MBPS). MBPS is considered to be an independent risk factor for cardiovascular disease. The aim of this study was to investigate the associations between MBPS, graft function, arterial stiffness and echocardiographic indicies in renal transpant recipients.

METHODS

Among 600 renal transplant recipients, 122 patients who had a history of hypertension and were taking at least one antihypertensive medication were enrolled in the study. Arterial stiffness was measured by carotid-femoral pulse wave velocity (PWv), and echocardiographic indicies were assessed. 24 hour ambulatory blood pressure was monitored for all patients. MBPS was calculated by substracting morning systolic blood pressure from minimal asleep systolic blood pressure.

RESULTS

Mean morning, day time and asleep systolic blood pressure values were 171.2± 23.9, 137.9± 18.1, and 131.7 ± 18.9 respectively. Non-dipper hypertention status was observed in 93 patients. Mean MBPS was 35.6 ± 19.5 mm Hg, mean PWv was 6.5 ± 2.0 m/sec. Patients with MBPS ≥ 35 mm Hg, had significantly lower eGFR and higher proteinuria, PWv. higher left atrium volume and LVMI. In regression analysis, day time systolic blood pressure, asleep systolic blood pressure, morning blood pressure surge, non-dipper status and left ventricular mass index were detected as the predictors of graft function.

CONCLUSIONS

Increased morning blood pressure surge is associated with graft dysfunction, increased arterial stiffness and LVMI that contributes to cardiovascular mortality and morbidity in renal transplant recipients. This article is protected by copyright. All rights reserved.

New onset hypertension after transplantation

It has been reported that up to 90% of organ transplant recipients have suboptimal blood pressure control. Uncontrolled hypertension is a well-known culprit of cardiovascular and overall morbidity and mortality. In addition, rigorous control of hypertension after organ transplantation is a crucial factor in prolonging graft survival. Nevertheless, hypertension after organ transplantation encompasses a broader range of causes than those identified in non-organ transplant patients. Hence, specific management awareness of those factors is mandated. An in-depth understanding of hypertension after organ transplantation remains a debatable issue that necessitates further clarification. This article provides a comprehensive review of the prevalence, risk factors, etiology, complications, prevention, and management of hypertension after organ transplantation.

Isolated nocturnal hypertension in pediatric kidney transplant recipients

BACKGROUND

Isolated nocturnal hypertension (INH) is defined as nighttime hypertension in the setting of normal daytime blood pressure (BP), diagnosed by ambulatory BP monitoring (ABPM).

METHODS AND RESULTS

Hypertension affects 60%-80% of pediatric kidney transplant recipients, and INH is the most common type of ambulatory hypertension. INH is associated with an increased prevalence of hypertension-mediated target organ damage such as left ventricular hypertrophy in adults and in pediatric kidney transplant recipients.

CONCLUSION

Ambulatory BP monitoring should be performed annually in all pediatric kidney transplant recipients to diagnose hypertension phenotypes that are not detectable by office BP such as masked hypertension, white-coat hypertension, or INH. Isolated nocturnal hypertension in pediatric transplant patients requires study as a treatment target.

KDOQI US Commentary on the 2021 KDIGO Clinical Practice Guideline for the Management of Blood Pressure in CKD

The Kidney Disease Outcomes Quality Initiative (KDOQI) convened a work group to review the 2021 KDIGO (Kidney Disease: Improving Global Outcomes) guideline for the management of blood pressure in chronic kidney disease (CKD). This commentary is the product of that work group and presents the recommendations and practice points from the KDIGO guideline in the context of US clinical practice. A critical addition to the KDIGO guideline is the recommendation for accurate assessment of blood pressure using standardized office blood pressure measurement. In the general adult population with CKD, KDIGO recommends a goal systolic blood pressure less than 120 mm Hg on the basis of results from the Systolic Blood Pressure Intervention Trial (SPRINT) and secondary analyses of the Action to Control Cardiovascular Risk in Diabetes-Blood Pressure (ACCORD-BP) trial. The KDOQI work group agreed with most of the recommendations while highlighting the weak evidence base especially for patients with diabetes and advanced CKD.

Sodium-glucose cotransporter-2 inhibitors (SGLT2i) in kidney transplant recipients: what is the evidence?

Several recent randomized controlled trials (RCTs) have demonstrated the wide clinical application of sodium-glucose cotransporter-2 inhibitors (SGLT2i) in improving kidney and cardiovascular outcomes in patients with native kidney disease. In April 2021, Dapagliflozin became the first SGLT2 inhibitor to be approved by the Food and Drug Administration (FDA) for the treatment of chronic kidney disease (CKD) regardless of diabetic status. However, while these agents have drawn much acclaim for their cardiovascular and nephroprotective effects among patients with native kidney disease, little is known about the safety and efficacy of SGLT2i in the kidney transplant setting. Many of the mechanisms by which SGLT2i exert their benefit stand to prove equally as efficacious or more so among kidney transplant recipients as they have in patients with CKD. However, safety concerns have excluded transplant recipients from all large RCTs, and clinicians and patients alike are left to wonder if the benefits of these amazing drugs outweigh the risks. In this review, we will discuss the known mechanisms SGLT2i exploit to provide their beneficial effects, the potential benefits, and risks of these agents in the context of kidney transplantation, and finally, we will discuss current findings of the published literature for SGLT2i use in kidney transplant recipients and propose potential directions for future research.

What is the goal blood pressure in kidney transplant recipients?

Arterial hypertension is a frequent condition after kidney transplantation and its treatment is a common agenda of the follow- up care. Retrospective data show that treatment of arterial hypertension decreases the risk of kidney graft loss. While randomized controlled trials for target blood pressures in kidney transplant recipients are not available, < 130/80 mm Hg is the most frequently mentioned value. Generally, all classes of antihypertensive drugs can be used, but it is important to consider timing after transplantation and possible interactions with immunosuppressive drugs.

Cardiovascular Effects of Autologous Bone Marrow-Derived Mesenchymal Stromal Cell Therapy With Early Tacrolimus Withdrawal in Renal Transplant Recipients: An Analysis of the Randomized TRITON Study

Background After renal transplantation, there is a need of immunosuppressive regimens that effectively prevent allograft rejection while minimizing cardiovascular complications. This substudy of the TRITON trial evaluated the cardiovascular effects of autologous bone marrow-derived mesenchymal stromal cells (MSCs) in renal transplant recipients. Methods and Results Renal transplant recipients were randomized to MSC therapy, infused at weeks 6 and 7 after transplantation, with withdrawal at week 8 of tacrolimus or standard tacrolimus dose. Fifty-four patients (MSC group=27; control group=27) underwent transthoracic echocardiography at weeks 4 and 24 after transplantation and were included in this substudy. Changes in clinical and echocardiographic variables were compared. The MSC group showed a benefit in blood pressure control, assessed by a significant interaction between changes in diastolic blood pressure and the treatment group (P=0.005), and a higher proportion of patients achieving the predefined blood pressure target of <140/90 mm Hg compared with the control group (59.3% versus 29.6%, P=0.03). A significant reduction in left ventricular mass index was observed in the MSC group, whereas there were no changes in the control group (P=0.002). The proportion of patients with left ventricular hypertrophy decreased at 24 weeks in the MSC group (33.3% versus 70.4%, P=0.006), whereas no changes were noted in the control group (63.0% versus 48.1%, P=0.29). Additionally, MSC therapy prevented progressive left ventricular diastolic dysfunction, as demonstrated by changes in mitral deceleration time and tricuspid regurgitant jet velocity. Conclusions MSC strategy is associated with improved blood pressure control, regression of left ventricular hypertrophy, and prevention of progressive diastolic dysfunction at 24 weeks after transplantation. Registration URL: https://www.clinicaltrials.gov; Unique identifier: NCT03398681.

Role of hypertension in kidney transplant recipients

Cardiovascular events are one of the leading causes of mortality in kidney transplant recipients. Hypertension is the most common comorbidity accompanying chronic kidney disease, with prevalence remaining as high as 90% even after kidney transplantation. It is often poorly controlled. Abnormal blood pressure profiles, such as masked or white-coat hypertension, are also extremely common in these patients. The pathophysiology of blood pressure elevation in kidney transplant recipients is complex and includes transplantation-specific risk factors, which are added to the traditional or chronic kidney disease-related factors. Despite these observations, hypertension management has been an under-researched area in kidney transplantation. Thus, relevant evidence derives either from studies in the general population or from small trials in kidney transplant recipients. Based on the relevant guidelines in the general population, lifestyle modifications should probably be applied as the first step of hypertension management in kidney transplant recipients. The optimal pharmacological management of hypertension in kidney transplant recipients is also not clear. Dihydropyridine calcium channel blockers are commonly used as first line agents because of their lack of adverse effects on the kidney, while other antihypertensive drug classes are under-utilised due to fear of the possible haemodynamic consequences on renal function. This review summarizes the existing data on the pathophysiology, diagnosis, prognostic significance and management of hypertension in kidney transplantation.

Relationship between renal function and blood pressure dipping status in renal transplant recipients: a longitudinal study

Background

Hypertension (HT) is associated with adverse outcomes in kidney transplant (KTX) recipients. Blunting of physiological decrease in nighttime compared to daytime blood pressure (non-dipping status) is frequent in this setting. However, weather non-dipping is independently associated with renal function decline in KTX patients is unknown.

Methods

We retrospectively screened KTX outpatients attending for a routine ambulatory blood pressure monitoring (ABPM) (T1) at a single tertiary hospital. Patients had two successive follow-up visits, 1 (T2) and 2 (T3) years later respectively. Routine clinical and laboratory data were collected at each visit. Mixed linear regression models were used with estimated glomerular filtration rate (eGFR) as the dependent variable.

Results

A total of 123 patients were included with a mean follow-up of 2.12 ± 0.45 years after ABPM. Mean age and eGFR at T1 were 56.0 ± 15.1 and 54.9 ± 20.0 mL/min/1.73m² respectively. 61 patients (50.4%) had sustained HT and 81 (65.8%) were non-dippers. In multivariate analysis, systolic dipping status was positively associated with eGFR (p = 0.009) and compared to non-dippers, dippers had a 10.4 mL/min/1.73m² higher eGFR. HT was negatively associated with eGFR (p = 0.003).

Conclusions

We confirm a high prevalence of non-dippers in KTX recipients. We suggest that preserved systolic dipping is associated with improved renal function in this setting independently of potential confounders, including HT and proteinuria. Whether modification of dipping status by chronotherapy would preserve renal function remains to be tested in clinical trials.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12882-021-02523-7.

Association between early post-transplant hypertension or related antihypertensive use and prognosis of kidney transplant recipients: a nationwide observational study

BACKGROUND

Additional research is warranted for the clinical significance of post-transplant hypertension and related antihypertensive medication use in kidney transplant (KT) recipients.

METHODS

This observational study included nationwide KT recipients who maintained a functioning graft for at least 1 year after KT in South Korea, observed between 2008 and 2017. The use of antihypertensive medications lasting between 6 months and 1 year was the main exposure, and those who had inconsistent/transient use of antihypertensive drugs were excluded. The prognostic outcome included death-censored graft failure (DCGF), death-with functioning graft (DWFG), and major adverse cerebrocardiovascular events (MACCEs).

RESULTS

We included 8,014 patients without post-transplant hypertension and 6,114 recipients who received treatment for hypertension in the post-transplant period. Those with post-transplant hypertension had a significantly higher risk of DCGF than those without [adjusted hazard ratio (HR) 1.27 (1.09-1.48)]. Post-transplant hypertension patients who required multiple drugs showed a significantly higher risk of DWFG [HR 1.57 (1.17-2.10)] and MACCE [HR 1.35 (1.01-1.81)] than the controls. Among the single-agent users, those who received beta-blockers showed a significantly higher risk of DCGF, although the risks of DWFG or MACCE were similar between the types of antihypertensive agents. Among the multiple agent users, the prognosis was similar, regardless of the prescribed types of antihypertensive agents.

CONCLUSION

Post-transplant hypertension was associated with poor post-transplant prognosis, particularly when multiple types of medications were required for treatment. During initial prescription of antihypertensive medication, clinicians may consider that beta-blockers were associated with a higher risk of DCGF in the single-agent users.

Hypertension in kidney transplantation: a consensus statement of the 'hypertension and the kidney' working group of the European Society of Hypertension

Hypertension is common in kidney transplantation recipients and may be difficult to treat. Factors present before kidney transplantation, related to the transplantation procedure itself and factors developing after transplantation may contribute to blood pressure (BP) elevation in kidney transplant recipients. The present consensus is based on the results of three recent systematic reviews, the latest guidelines and the current literature. The current transplant guidelines, which recommend only office BP assessments for risk stratification in kidney transplant patients should be reconsidered, given the presence of white-coat hypertension and masked hypertension in this population and the better prediction of adverse outcomes by 24-h ambulatory BP monitoring as indicated in recent systematic reviews. Hypertension is associated with adverse kidney and cardiovascular outcomes and decreased survival in kidney transplant recipients. Current evidence suggests calcium channel blockers could be the preferred first-step antihypertensive agents in kidney transplant patients, as they improve graft function and reduce graft loss, whereas no clear benefit is documented for renin-angiotensin system inhibitor use over conventional treatment in the current literature. Randomized control trials demonstrating the clinical benefits of BP lowering on kidney and major cardiovascular events and recording patient-related outcomes are still needed. These trials should define optimal BP targets for kidney transplant recipients. In the absence of kidney transplant-specific evidence, BP targets in kidney transplant recipients should be similar to those in the wider chronic kidney disease population.

Hypertension in Kidney Transplant Recipients: Where Are We Today?

PURPOSE OF REVIEW

Cardiovascular disease is the leading cause of death and allograft loss among kidney transplant recipients, and hypertension is an independent risk factor for cardiovascular morbidity of this patient population. The etiology of hypertension is multifactorial, including pre-transplant volume overload, post-transplant recipient and donor-associated variables, and transplant-specific causes (immunosuppressive medications, allograft dysfunction and surgical complications such as transplant artery stenosis).

RECENT FINDINGS

No randomized controlled trials have assessed the optimal blood pressure targets and explored the best antihypertensive regimen for kidney transplant recipients. According to the large observational studies, it is reasonable to achieve a blood pressure goal of equal to or less than 130/80 mmHg in the long-term follow-up for minimizing the cardiovascular morbidity. The selection of antihypertensive agents should be based on the patient's co-morbidities; however, the initial choice could be calcium channel blockers especially in the first few months of transplantation. In patients with cardiovascular indications of renin-angiotensin-aldosterone system inhibition, given the well-described benefits in diabetic and proteinuric patients, it is reasonable to consider the use of renin-angiotensin-aldosterone system inhibitors. There is a need for future prospective trials in the transplant population to define optimal blood pressure goals and therapies.

Blood Pressure Treatment in Kidney Transplant Recipients-Can We Improve?

Hypertension in kidney transplant (KTx) recipients is common, affecting both patient and graft survival. Annual data from the Norwegian Renal Registry reveal that <50% of adult (>18 y) KTx recipients reach target blood pressure (BP) ≤130/80 mm Hg. The aim of this study was to identify the determinants of failure to achieve BP control.

Should ACE inhibitors or calcium channel blockers be used for post-transplant hypertension?

Arterial hypertension in renal transplant recipients warrants antihypertensive treatment. The preferable choice of antihypertensives that should be used in patients after kidney transplantation remains a matter of debate; however, calcium channel blockers (CCB) and angiotensin-converting enzyme inhibitors (ACEI) are currently the most commonly used antihypertensives. This educational review summarizes the current evidence about the effects of these two classes of medications in transplant recipients. Several studies have demonstrated that both classes of drugs can reduce blood pressure (BP) to similar extents. Meta-analyses of adult randomized controlled trials have shown that graft survival is improved in patients treated with ACEIs and CCBs, and that CCBs increase, yet ACEIs decrease, graft function. Proteinuria is usually decreased by ACEIs but remains unchanged with CCBs. In children, no randomized controlled study has ever been performed to compare BP or graft survival between CCBs and ACEIs. Post-transplant proteinuria could be reduced in children along with BP by ACEIs. The results of the most current meta-analyses recommend that due to their positive effects on graft function and survival, along with their lack of negative effects on serum potassium, CCBs could be the preferred first-line antihypertensive agent in renal transplant recipients. However, antihypertensive therapy should be individually tailored based on other factors, such as time after transplantation, presence of proteinuria/albuminuria, or hyperkalemia. Furthermore, due to the difficulty in controlling hypertension, combination therapy containing both CCBs and ACEIs could be a reasonable first-step therapy in treating children with severe post-transplantation hypertension.

Antihypertensive Treatment in Kidney Transplant Recipients-A Current Single Center Experience

Arterial hypertension affects the survival of the kidney graft and the cardiovascular morbidity and mortality of the recipient after kidney transplantation (KTx). Thus, antihypertensive treatment is necessary for a vast majority of these patients. Long-term data on antihypertensive drugs and their effects on allograft function after KTx is still limited, and further investigation is required. We retrospectively analyzed a cohort of 854 recipients who received a kidney transplant at our transplant center between 2007 and 2015 with regard to antihypertensive treatment and its influence on graft function and survival. 1-y after KTx, 95.3% patients were treated with antihypertensive therapy. Of these, 38.6% received mono- or dual-drug therapy, 38.0% received three to four drugs and 8.1% were on a regimen of ≥5 drugs. Beta-blockers were the most frequently used antihypertensive agents (68.1%). Neither the use of angiotensin-converting enzyme inhibitor/angiotensin receptor blockers (51.9%) and calcium channel blockers (51.5%), nor the use the use of loop diuretics (38.7%) affected allograft survival. Arterial hypertension and the number of antihypertensive agents were associated with unfavorable allograft outcomes (each p < 0.001). In addition to the well-known risk factors of cold ischemic time and acute rejection episodes, the number of antihypertensive drugs after one year, which reflects the severity of hypertension, is a strong predictor of unfavorable allograft survival.

Role of Prior Split Renal Function for Living Kidney Transplantation in Recipients and Donors

PURPOSE

The purpose of this study was to determine the relationship between pre-operative donor split renal function (SRF) and the renal function outcome of donors and recipients after kidney transplantation (KT).

METHODS

A total of 217 living KT cases were investigated. The estimated glomerular filtration rate (eGFR) change of recipients and donors, as well as graft survival, were analyzed based on the donor SRF. The difference in SRF (dSRF) in a donor was defined as follows: the SRF of the donated kidney minus the SRF of the remaining kidney determined by pre-operative ^99mTc-diethylenetriaminepentaacetic acid in the donors. The dSRF was categorized into tertiles.

RESULTS

The dSRF was not associated with the eGFR in recipients in any tertile at 6 or 12 months post-KT. The overall graft and patient survival did not differ significantly among tertiles. Donors in the high tertile, who donated kidneys with a higher SRF, showed a greater reduction in eGFR than did donors in the low and middle tertile after adjustment for function of the not-donated kidney (-34 ± 1.9 vs -28 ± 2.2, and -27 ± 1.3 mL/min/1.73 m², P < .05).

CONCLUSIONS

The dSRF did not affect the post-KT renal function or graft survival in recipients. However, the donors who donated the better functioning kidney had a poorer renal function after donation.

Approach and Management of Hypertension After Kidney Transplantation

Hypertension is one of the most common cardiovascular co-morbidities after successful kidney transplantation. It commonly occurs in patients with other metabolic diseases, such as diabetes mellitus, hyperlipidemia, and obesity. The pathogenesis of post-transplant hypertension is complex and is a result of the interplay between immunological and non-immunological factors. Post-transplant hypertension can be divided into immediate, early, and late post-transplant periods. This classification can help clinicians determine the etiology and provide the appropriate management for these complex patients. Volume overload from intravenous fluid administration is common during the immediate post-transplant period and commonly contributes to hypertension seen early after transplantation. Immunosuppressive medications and donor kidneys are associated with post-transplant hypertension occurring at any time point after transplantation. Transplant renal artery stenosis (TRAS) and obstructive sleep apnea (OSA) are recognized but common and treatable causes of resistant hypertension post-transplantation. During late post-transplant period, chronic renal allograft dysfunction becomes an additional cause of hypertension. As these patients develop more substantial chronic kidney disease affecting their allografts, fibroblast growth factor 23 (FGF23) increases and is associated with increased cardiovascular and all-cause mortality in kidney transplant recipients. The exact relationship between increased FGF23 and post-transplant hypertension remains poorly understood. Blood pressure (BP) targets and management involve both non-pharmacologic and pharmacologic treatment and should be individualized. Until strong evidence in the kidney transplant population exists, a BP of <130/80 mmHg is a reasonable target. Similar to complete renal denervation in non-transplant patients, bilateral native nephrectomy is another treatment option for resistant post-transplant hypertension. Native renal denervation offers promising outcomes for controlling resistant hypertension with no significant procedure-related complications. This review addresses the epidemiology, pathogenesis, and specific etiologies of post-transplant hypertension including TRAS, calcineurin inhibitor effects, OSA, and failed native kidney. The cardiovascular and survival outcomes related to post-transplant hypertension and the utility of 24-h blood pressure monitoring will be briefly discussed. Antihypertensive medications and their mechanism of actions relevant to kidney transplantation will be highlighted. A summary of guidelines from different professional societies for BP targets and antihypertensive medications as well as non-pharmacological interventions, including bilateral native nephrectomy and native renal denervation, will be reviewed.

Changes in Office Blood Pressure Control, Augmentation Index, and Liver Steatosis in Kidney Transplant Patients after Successful Hepatitis C Infection Treatment with Direct Antiviral Agents

Hepatitis C virus (HCV) infection in kidney transplant recipients (KTRs) can be successfully treated with direct antiviral agents (DAA). The aim of our study was to analyze different measures of vascular function during and after the DAA treatment. As we have observed the improvement of blood pressure (BP) control in some individuals, we have conducted an analysis of potential explanatory mechanisms behind this finding. Twenty-eight adult KTRs were prospectively evaluated before and 15 months after start of DAA therapy. Attended office BP (OBP), augmentation index (AIx), pulse wave velocity (PWV), flow-mediated dilation (FMD), liver stiffness measurement (LSM), and liver steatosis assessment (controlled attenuation parameter (CAP)) were measured. In half of the patients, improvement of OBP control (decline of systolic BP by at least 20 mmHg or reduction of the number of antihypertensive drugs used) and parallel central aortic pressure parameters, including AIx, was observed. There was a significant decrease in CAP mean values (241 ± 54 vs. 209 ± 30 dB/m, p < 0.05) only in patients with OBP control improvement. Half of our KTRs cohort after successful HCV eradication noted clinically important improvement of both OBP control and central aortic pressure parameters, including AIx. The concomitant decrease of liver steatosis was observed only in the subgroup of patients with improvement of blood pressure control.

Urinary sulfate excretion and risk of late graft failure in renal transplant recipients - a prospective cohort study

Hydrogen sulfide (H₂S), produced from metabolism of dietary sulfur‐containing amino acids, is allegedly a renoprotective compound. Twenty‐four‐hour urinary sulfate excretion (USE) may reflect H₂S bioavailability. We aimed to investigate the association of USE with graft failure in a large prospective cohort of renal transplant recipients (RTR). We included 704 stable RTR, recruited at least 1 year after transplantation. We applied log‐rank testing and Cox regression analyses to study association of USE, measured from baseline 24 h urine samples, with graft failure. Median age was 55 [45–63] years (57% male, eGFR was 45 ± 19 ml/min/1.73 m²). Median USE was 17.1 [13.1–21.1] mmol/24 h. Over median follow‐up of 5.3 [4.5–6.0] years, 84 RTR experienced graft failure. RTR in the lowest sex‐specific tertile of USE experienced a higher rate of graft failure during follow‐up than RTR in the middle and highest sex‐specific tertiles (18%, 13%, and 5%, respectively, log‐rank P < 0.001). In Cox regression analyses, USE was inversely associated with graft failure [HR per 10 mmol/24 h: 0.37 (0.24–0.55), P < 0.001]. The association remained independent of adjustment for potential confounders, including age, sex, eGFR, proteinuria, time between transplantation and baseline, BMI, smoking, and high sensitivity C‐reactive protein [HR per 10 mmol/24 h: 0.51 (0.31–0.82), P = 0.01]. In conclusion, this study demonstrates a significant inverse association of USE with graft failure in RTR, suggesting high H₂S bioavailability as a novel, potentially modifiable factor for prevention of graft failure in RTR.

Late Renal Transplant Failure: An Adverse Prognostic Factor at Initiation of Peritoneal Dialysis

Background

Early renal transplant failure necessitating a return to dialysis has been shown to be a poor prognostic factor for survival. Little is known about the outcome of patients with late transplant failure returning to dialysis. It was our clinical impression that late transplant failure (>2 months) carries an increased morbidity and mortality risk in patients returning to dialysis.

Objective

To determine whether patients with a failed renal transplant have an outcome different to those on dialysis who have never received a kidney transplant.

Setting

Peritoneal dialysis (PD) unit in a teaching hospital.

Patients and Design

All failed renal transplant patients (fTx) in the Toronto Hospital Peritoneal Dialysis program between 1989 and 1996 were identified. This cohort of 42 fTx patients was compared with a cohort of randomly selected never-transplanted PD patients (non-Tx). The PD program was selected because of the availability of well-documented patient archival material. The non-Tx group was matched for age and presence of diabetes. Data were collected until retransplantation, change of dialysis modality or center, death, or until June 1998.

Results

There was no difference at initiation of PD between groups in serum albumin, residual renal function, or mean serum parathyroid hormone level. The mean low-density lipoprotein level was significantly higher in the fTx cohort. The duration of dialysis before Tx in fTx patients accounted for the increased total length of dialysis in fTx (mean 15 months). However, post-Tx the duration of PD was similar for both groups (30.7 months for fTx vs 31.6 months for non-Tx). The fTx group had a considerably worse outcome than the non-Tx group. The time to first peritonitis, subsequent episodes of peritonitis, catheter change, or transfer to hemodialysis occurred at a much faster rate in fTx patients. The most dramatic difference was in survival. There were 3 deaths in the non-Tx group and 12 in the fTx group ( p < 0.01). The mean age at time of death in the fTx group was 47.5 years. Deaths were due mainly to gram-negative peritonitis and cardiovascular disease.

Conclusions

W e conclude that late failed renal transplant patients starting dialysis are at increased risk of complications and have strikingly higher mortality rates than non-Tx patients. A previously failed kidney transplant can be considered an adverse prognostic factor for patients commencing PD; these patients need to be closely monitored. Although this study was limited to PD patients, the same principles likely apply to fTx patients returning to any form of renal replacement therapy.

Blood Pressure, Chronic Kidney Disease Progression, and Kidney Allograft Failure in Kidney Transplant Recipients: A Secondary Analysis of the FAVORIT Trial

BACKGROUND

In chronic kidney disease, intensive systolic blood pressure (SBP) control reduces mortality at a cost of greater acute kidney injury risk. Kidney transplantation involves implantation of denervated kidneys and immunosuppressive medications that increase acute kidney injury risk. The optimal blood pressure (BP) target in kidney transplant recipients (KTRs) is uncertain. Prior observational studies from the Folic Acid for Vascular Outcome Reduction in Transplantation (FAVORIT) trial demonstrate associations of lower SBP levels and reduced mortality risk, but the relationship of BP with kidney allograft function remains unknown. Thus, in FAVORIT, we investigated the relationship of SBP and diastolic blood pressure (DBP) with risk of kidney allograft failure and estimated glomerular filtration rate (eGFR) slope among stable KTRs.

METHODS

Cox proportional hazards and multivariable linear regression models adjusted for demographics, transplant characteristics, comorbidities, baseline eGFR, and urine albumin-to-creatinine ratio were used to determine associations of SBP and DBP with time to a composite kidney outcome of ≥50% eGFR decline or dialysis dependence, and with annualized eGFR change, respectively. Multivariable restricted cubic spline plots were developed to evaluate the functional form of the relationships.

RESULTS

Among 3,598 KTRs, mean age was 52 ± 9 years, SBP was 136 ± 20 mm Hg, DBP was 79 ± 12 mm Hg, and eGFR was 49 ± 18 ml/minute/1.73 m2. There were 369 events of ≥50% eGFR decline or dialysis dependence during a mean follow-up of 4.0 ± 1.5 years. There was no association of either SBP (compared with SBP 120 to <130 mm Hg, hazard ratio (HR) for the SBP < 110 was 1.01 (95% confidence interval (CI) 0.60 to 1.70) and 130 to <140 was 0.89 (0.64 to 1.24)) or DBP (compared with DBP 70 to <80 mm Hg, HR for the DBP 60 to <70 was 1.00 (95% CI 0.74 to 1.34) and 80 to <90 was 0.90 (0.68 to 1.18)) with the kidney failure outcome or annualized eGFR slope, and, when examined using restricted cubic splines, there was no evidence of "J"- or "U"-shaped relationships.

CONCLUSIONS

In a large sample of stable KTRs, we found no evidence of thresholds at which lower BPs were related to higher risk of allograft failure or eGFR decline. In light of prior findings of mortality benefit at low SBP, these observational findings suggest lower BP may be beneficial in KTRs. This important question requires confirmation in future randomized trials in KTRs.

Masked Hypertension and Obesity in Renal Transplant Recipients

The diagnosis of arterial hypertension has traditionally been based on measurements of blood pressure (BP) in the clinic. However, home or ambulatory BP monitoring (ABPM) is reported to correlate better with target organ damage than clinic BP readings. The other potential advantage of out-of-clinic BP measurement is the detection of both white-coat hypertension (WCHT) and masked hypertension (MHT). Studies have suggested that MHT have an increased risk of cardiovascular disease (CVD). We aimed to investigate the prevalence of MHT and to evaluate risk factors by ABPM in our renal transplant recipients. One hundred twenty-ninety patients who were followed up in our nephrology clinic were included in the study. The prevalence of MHT was 17%. In logistic regression analysis, we investigated factors associated with MHT. In a model with age, sex, smoking, presence of Diabetes mellitus (DM) and blood glucose, estimated glomerular filtration rate (eGFR), donor type, body mass index, waist circumference (WC), waist-to-hip ratio (WHR), and waist-to-height ratio (WHtR), we found that WHR (r: 18.61, P: .007) and smoking (r: 2.79, P: .011) were related with MHT. MHT was related to target organ damage and cardiovascular disease. The diagnosis and treatment of MHT are important. These findings suggesting that patients with high WC and smokers should be investigated with ABPM to diagnose masked hypertension. This approach may reduce adverse cardiovascular outcomes after transplantation.

Ambulatory monitoring unmasks hypertension among kidney transplant patients: single center experience and review of the literature

Background

Disagreements between clinic and ambulatory blood pressure (BP) measurements are well-described in the general population. Though hypertension is frequent in renal transplant recipients, only a few studies address the clinic-ambulatory discordance in this population. We aimed to describe the difference between clinic and ambulatory BP in kidney transplant patients at our institution.

Methods

We compared the clinic and ambulatory BP of 76 adult recipients of a kidney allograft followed at our transplant center and investigated the difference between these methods, considering confounding by demographic and clinical variables.

Results

Clinic systolic BP (SBP) and diastolic BP (DBP) were 128 ± 13/79 ± 9 mmHg. Awake SBP and DBP were 147 ± 18/85 ± 10 mmHg. The clinic-minus-awake SBP and DBP differences were − 18 and − 6 mmHg, respectively. The negative clinic-awake ΔSBP was more pronounced at age > 60 years (p = 0.026) and with tacrolimus use compared to cyclosporine (p = 0.046). Sleep SBP and DBP were 139 ± 21/78 ± 11 mmHg. A non-dipping sleep BP pattern was noted in 73% of patients and was associated with tacrolimus use (p = 0.020).

Conclusions

Our findings suggest pervasive underestimation of BP when measured in the kidney transplant clinic, emphasizes the high frequency of a non-dipping pattern in this population and calls for liberal use of ambulatory BP monitoring to detect and manage hypertension.

Electronic supplementary material

The online version of this article (10.1186/s12882-019-1442-7) contains supplementary material, which is available to authorized users.

Cardiovascular risk in renal transplant recipients

Successful kidney transplantation offers patients with end-stage renal disease the greatest likelihood of survival. However, cardiovascular disease poses a major threat to both graft and patient survival in this cohort. Transplant recipients are unique in their accumulation of a wide range of traditional and non-traditional cardiovascular risk factors. Hypertension, diabetes, dyslipidaemia and obesity are highly prevalent in patients with end-stage renal disease. These risk factors persist following transplantation and are often exacerbated by the drugs used for immunosuppression in organ transplantation. Additional transplant-specific factors such as poor graft function and proteinuria are also associated with increased cardiovascular risk. However, these transplant-related factors remain unaccounted for in current cardiovascular risk prediction models, making it challenging to identify transplant recipients with highest risk. With few interventional trials in this area specific to transplant recipients, strategies to reduce cardiovascular risk are largely extrapolated from other populations. Aggressive management of traditional cardiovascular risk factors remains the cornerstone of prevention, though there is also a potential role for selecting immunosuppression regimens to minimise additional cardiovascular injury.

Hypertension after Kidney Transplantation: Clinical Significance and Therapeutical Aspects

Most of the kidney transplanted patients develop arterial hypertension after renal transplantation. Together with very well-known and usual risk factors, post-transplant hypertension contributes to the whole cardiovascular morbidity and mortality in the kidney transplant population. The reasons of post-transplant hypertension are factors related to donors and recipients, immunosuppressive therapy like Calcineurin Inhibitors (CNI) and surgery procedures (stenosis and kinking of the renal artery and ureteral obstruction). According to Eighth National Committee (JNC 8) recommendations, blood pressure > 140/90 mmHg is considered as hypertension. The usual antihypertensive drugs used for the control of hypertension are Calcium channel blockers (CCB), Angiotensin-converting enzyme (ACE) inhibitors, Angiotensin -II receptor blockers (ARB), B- blockers and diuretics. Follow the KDIGO guidelines the target blood pressure < 140/90 mmHg for patients without proteinuria and < 125/75 mmHg in patients with proteinuria is recommended. Better control of post-transplant hypertension improves the long-term graft and patient's survival.

Ambulatory Blood Pressure Monitoring: Profiles in Chronic Kidney Disease Patients and Utility in Management

Optimal control of blood pressure (BP) may reduce the risk of progression of CKD. Misclassification of hypertension (HTN) and status of control may result in suboptimal management. Clinic or home BP may overestimate or underestimate status of control compared with ambulatory BP monitoring (ABPM), which is considered the gold standard. The latter relates not only to the superiority of ABPM concerning outcome prognosis but also to its ability to accurately diagnose white coat and masked HTN, which is critical in assuring adequate BP control. However, ABPM has not gained widespread use in practice because of limited third-party reimbursement and a paucity of high quality randomized controlled intervention studies evaluating its use. Herein, we review HTN phenotypes that have been identified in patients with CKD, and the potential value of ABPM in this high-risk population.

Effects of the strict control of blood pressure in pediatric renal transplant recipients-ESCORT trial

OBJECTIVES

Strict BP control can retard progression of CKD in children. This prospective 3-year randomized controlled trial is aimed to investigate whether strict BP control can retard progression of chronic allograft dysfunction.

METHODS

Twenty-three pediatric patients were randomly selected to the standard BP group (STAND, target 24-hour MAP 50-95th percentile, n = 11) or the intensified BP group (INTENS, target 24-hour MAP <50th percentile, n = 12). The primary endpoint was an annual reduction in eGFR (Schwartz formula, mL/min/1.73 m² /y), secondary graft survival, BP, proteinuria, and safety.

RESULTS

A total of 21 children (age at entry 11.2 (range 6.2-16.8) years) completed the study, with 73% of children in INTENS and 70% of children in STAND group reached their goal BP. Ambulatory indexed 24-hour MAP decreased significantly in INTENS group (from 0.94 (range 0.86-1.17) to 0.85 (range 0.79-1.01, P < 0.01)) but not in STAND group (from 0.93 (range 0.85-1.07) to 0.90 (range 0.84-1.01)). Proteinuria did not change significantly in either group (22.1 mg/mmol creatinine to 15.3 in STAND group vs 25.7 to 11.8 in INTENS group). The annual reduction in eGFR did not differ between the INTENS and STAND groups (-1.9 mL/min/1.73 m² /y (range +6.4 to -14.3) vs -0.9 (range +4.0 to -8.5)).

CONCLUSION

This first randomized controlled trial on strict BP control has demonstrated that strict BP control is feasible in 73% of children but the strict BP control does not lead to retardation of graft function decline in comparison with standard BP control. However, the results need to be interpreted with caution keeping the major limitation of the study, that is, small sample size in mind.

The impact of blood pressure variability and pulse pressure on graft survival and mortality after kidney transplantation

BACKGROUND

Blood pressure variability and pulse pressure are strong and independent predictors of cardiovascular morbidity and mortality in the general population. So far, there are no data on the impact of blood pressure variability on mortality and graft survival after renal transplantation.

METHODS

We performed a retrospective analysis of 877 patients who underwent kidney transplantation between 1997 and 2011 in two transplant centers in Germany (Berlin and Bochum) with a follow-up of 12-266 months. Visit-to-visit blood pressure variability over the first 12 months after transplantation (3 visits) and during the first 120 months after transplantation (7 visits) was calculated as the coefficient of variation (CV = standard deviation (SD)/mean blood pressure). Patient and graft survival was defined as composite endpoint.

RESULTS

Cumulative survival was significantly higher for those patients with lower systolic blood pressure and pulse pressure within both the first 12 months and the 120 months posttransplant. After adjustment of data for gender, age, body mass index, and coronary artery disease, the cumulative incidence of the combined endpoint did not significantly differ between patients with lower vs higher CV (12 months CV hazard ratio (HR) (95% CI) = 0.90 (0.66-1.23), P = 0.51; 120 months CV HR (95% CI) = 0.92 (0.67-1.26), P = 0.60). A lower systolic blood pressure remained highly predictive for better survival in adjusted analyses.

CONCLUSION

Visit-to-visit blood pressure variability is not associated with mortality or graft loss after kidney transplantation in this retrospective analysis. In analogy to the general population, however, there is an inverse relationship of survival and pulse pressure as a marker of arterial stiffness.

Dietary Approach to Stop Hypertension (DASH) diet and risk of renal function decline and all-cause mortality in renal transplant recipients

Renal transplant recipients (RTR) are at risk of decline of graft function and premature mortality, with high blood pressure as an important risk factor for both. To study the association of the Dietary Approach to Stop Hypertension (DASH) diet with these adverse events, we conducted a prospective cohort study of adult RTR. Dietary data were collected using a validated 177-item food frequency questionnaire and an overall DASH-score was obtained. We included 632 stable RTR (mean ± standard deviation age 53.0 ± 12.7 years, 57% men). Mean DASH score was 23.8 ± 4.7. During median follow-up of 5.3 (interquartile range, 4.1-6.0) years, 119 (18.8%) RTR had renal function decline, defined as a combined endpoint of doubling of serum creatinine and death-censored graft failure, and 128 (20.3%) died. In Cox-regression analyses, RTR in the highest tertile of the DASH score had lower risk of both renal function decline (hazard ratio [HR] = 0.57; 95% confidence interval [CI], 0.33-0.96, P = .03) and all-cause mortality (HR = 0.52; 95%CI, 0.32-0.83, P = .006) compared to the lowest tertile, independent of potential confounders. Adherence to a DASH-style diet is associated with lower risk of both renal function decline and all-cause mortality. These results suggest that a healthful diet might benefit long-term outcome in RTR.

Pulse Pressure and Outcome in Kidney Transplantation: Results From the Collaborative Transplant Study

BACKGROUND

Systolic blood pressure (SBP) and diastolic blood pressure (DBP) are important predictors of graft and patient survival in renal transplantation. Pulse pressure (PP), the difference between systolic and diastolic pressure, has been associated with cardiovascular and renal morbidity in nontransplant epidemiological studies and clinical trials.

METHODS

In this large retrospective analysis of prospectively collected data, transplant recipients from 1995 to 2015 were examined for patient and death-censored graft survival.

RESULTS

In 43 006 recipients, a higher 1-year PP was significantly associated with inferior 10-year patient and death-censored graft survival. In patients 60 years or older, SBP but not DBP was associated with 10-year survival, an effect that was pronounced in patients with a normal SBP of <140 mm Hg and an increased PP of 60 mm Hg or greater, highlighting the superior impact of PP on survival in elderly recipients. In recipients 60 years or older, higher PP was associated with increased mortality due to circulatory system diseases but not to infection or cancer. The combination of PP 60 mm Hg or greater and high SBP of 140 mm Hg or greater showed the strongest association with death-censored graft survival across all age groups.

CONCLUSIONS

We found convincing evidence that PP 1-year posttransplant is predictive of patient survival, especially in elderly recipients with normal SBP. Combined analysis of SBP and PP showed that high PP confers additional predictive information for patient survival beyond that derived from analysis of SBP alone. With regard to prediction of death-censored graft survival, the combination of high SBP and high PP showed the best correlation across all age groups.

Arterial stiffness but not endothelial dysfunction is associated with multidrug antihypertensive therapy and nondipper blood pressure pattern in kidney transplant recipients

Vascular injury related to chronic kidney disease results in increased arterial stiffness and endothelial dysfunction which may affect arterial blood pressure (BP) and influence patient and graft survival in kidney transplant recipients (KTRs).This cross-sectional study aims to elucidate the relationship between the above-mentioned measures of vascular damage and effectiveness of antihypertensive treatment in KTR.One hundred forty-five KTRs 7.6 ± 2.7 years after transplantation were enrolled in our study. Pulse wave velocity (PWV), flow-mediated dilation (FMD), and nitroglycerin-mediated dilation (NMD) were measured, and 24-hour ambulatory BP monitoring was performed.Overall, there were 62 patients with well-controlled or borderline BP and 83 subjects who did not achieve target BP despite antihypertensive treatment. Patients with suboptimal BP control were characterized by greater PWV (median 9.6/interquartile range: 3.9 vs 8.0/3.3 m/s, P = .002), but borderline lower FMD (8.4% ± 5.0% vs 9.9% ± 5.7%; P = .09) as compared with the group with better BP control. When patients were allocated to subgroups based on the number of current antihypertensive medications, no differences in FMD and NMD were found. However, a significant trend was observed for higher PWV values and decreased proportion of dippers along with the increasing number of drugs. PWV, diabetes, and total cholesterol level, but not FMD or NMD, were explanatory variables for systolic BP in multivariate analysis.Arterial stiffness but not endothelial dysfunction is associated with suboptimal BP control in stable KTRs. Less efficient antihypertensive treatment appears to be caused by inadequate control of nocturnal BP.