Optimizing hypertension management in renal transplantation: a call to action

Interaction between tacrolimus and calcium channel blockers based on CYP3A5 genotype in Chinese renal transplant recipients

Objective

To investigate the effect of calcium channel blockers (CCBs) on tacrolimus blood concentrations in renal transplant recipients with different CYP3A5 genotypes.

Methods

This retrospective cohort study included renal transplant recipients receiving tacrolimus-based immunosuppressive therapy with or without CCBs in combination. Patients were divided into combination and control groups based on whether or not they were combined with CCBs, and then further analyzed according to the type of CCBs (nifedipine/amlodipine/felodipine). Propensity score matching was conducted for the combination and the control groups using SPSS 22.0 software to reduce the impact of confounding factors. The effect of different CCBs on tacrolimus blood concentrations was evaluated, and subgroup analysis was performed according to the patients' CYP3A5 genotypes to explore the role of CYP3A5 genotypes in drug-drug interactions between tacrolimus and CCBs.

Results

A total of 164 patients combined with CCBs were included in the combination groups. After propensity score matching, 83 patients with nifedipine were matched 1:1 with the control group, 63 patients with felodipine were matched 1:2 with 126 controls, and 18 patients with amlodipine were matched 1:3 with 54 controls. Compared with the controls, the three CCBs increased the dose-adjusted trough concentration (C0/D) levels of tacrolimus by 41.61%-45.57% (P < 0.001). For both CYP3A5 expressers (CYP3A5*1*1 or CYP3A5*1*3) and non-expressers (CYP3A5*3*3), there were significant differences in tacrolimus C0/D between patients using felodipine/nifedipine and those without CCBs (P < 0.001). However, among CYP3A5 non-expressers, C0/D values of tacrolimus were significantly higher in patients combined with amlodipine compared to the controls (P = 0.001), while for CYP3A5 expressers, the difference in tacrolimus C0/D values between patients with amlodipine and without was not statistically significant (P = 0.065).

Conclusion

CCBs (felodipine/nifedipine/amlodipine) can affect tacrolimus blood concentration levels by inhibiting its metabolism. The CYP3A5 genotype may play a role in the drug interaction between tacrolimus and amlodipine. Therefore, genetic testing for tacrolimus and therapeutic drug monitoring are needed when renal transplant recipients are concurrently using CCBs.

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.

Blood pressure management and long-term outcomes in kidney transplantation: a holistic view over a 35-year period

INTRODUCTION

Hypertension is a burden for most kidney transplant recipients. Whether respect of hypertension guidelines results in better outcomes is unknown.

METHODS

In this multicenter study, office blood pressure at 12 months following transplantation (i.e., after > 20 outpatient visits), and survival were assessed over 35 years among 2004 consecutive kidney transplant recipients who received a first kidney graft from 1985 to 2019 (follow-up: 26,232 patient-years).

RESULTS

Antihypertensive medications were used in 1763/2004 (88.0%) patients. Renin-angiotensin-system blockers were used in 35.6% (47.1% when proteinuria was > 0.5 g/day) and calcium-channel blockers were used in 6.0% of patients. Combined treatment including renin-angiotensin-system-blockers, calcium-channel blockers and diuretics was used in 15.4% of patients receiving ≥ 3 antihypertensive drugs. Blood pressure was controlled in 8.3%, 18.8% and 43.1%, respectively, depending on definition (BP < 120/80, < 130/80, < 140/90 mmHg, respectively) and has not improved since the year 2001. Two-thirds of patients with uncontrolled blood pressure received < 3 antihypertensive classes. Low sodium intake < 2 g/day (vs ≥ 2) was not associated with better blood pressure control. Uncontrolled blood pressure was associated with lower patient survival (in multivariable analyses) and graft survival (in univariate analyses) vs controlled hypertension or normotension. Low sodium intake and major antihypertensive classes had no influence on patient and graft survival.

CONCLUSIONS

Pharmacological recommendations and sodium intake reduction are poorly respected, but even when respected, do not result in better blood pressure control, or patient or graft survival. Uncontrolled blood pressure, not the use of specific antihypertensive classes, is associated with reduced patient, and to a lesser extent, reduced graft survival, even using the 120/80 mmHg cut-off.

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.

Assessment of hypertension in kidney transplantation by ambulatory blood pressure monitoring: a systematic review and meta-analysis

Background

Hypertension (HTN) is common following renal transplantation and it is associated with adverse effects on cardiovascular (CV) and graft health. Ambulatory blood pressure monitoring (ABPM) is the preferred method to characterize blood pressure (BP) status, since HTN misclassification by office BP (OBP) is quite common in this population. We performed a systematic review and meta-analysis aimed at determining the clinical utility of 24-h ABPM and its potential implications for the management of HTN in this population.

Methods

Ovid-MEDLINE and PubMed databases were searched for interventional or observational studies enrolling adult kidney transplant recipients (KTRs) undergoing 24-h ABP readings compared with OBP or home BP. The main outcome was the proportion of KTRs diagnosed with HTN by ABPM, home or OBP recordings. Additionally, day-night BP variability and dipper/non-dipper status were assessed.

Results

Forty-two eligible studies (4115 participants) were reviewed. A cumulative analysis including 27 studies (3481 participants) revealed a prevalence of uncontrolled HTN detected by ABPM of 56% [95% confidence interval (CI) 46-65%]. The pooled prevalence of uncontrolled HTN according to OBP was 47% (95% CI 36-58%) in 25 studies (3261 participants). Very few studies reported on home BP recordings. The average concordance rate between OBP and ABPM measurements in classifying patients as controlled or uncontrolled hypertensive was 66% (95% CI 59-73%). ABPM revealed HTN phenotypes among KTRs. Two pooled analyses of 11 and 10 studies, respectively, revealed an average prevalence of 26% (95% CI 19-33%) for masked HTN (MHT) and 10% (95% CI 6-17%) for white-coat HTN (WCH). The proportion of non-dippers was variable across the 28 studies that analysed dipping status, with an average prevalence of 54% (95% CI 45-63%).

Conclusions

In our systematic review, comparison of OBP versus ABP measurements disclosed a high proportion of MHT, uncontrolled HTN and, to a lesser extent, WCH in KTRs. These results suggest that HTN is not adequately diagnosed and controlled by OBP recordings in this population. Furthermore, the high prevalence of non-dippers confirmed that circadian rhythm is commonly disturbed in KTRs.

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.

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.

Update on Treatment of Hypertension After Renal Transplantation

PURPOSE OF REVIEW

To incorporate novel findings on pathophysiology and treatment of posttransplant hypertension.

RECENT FINDINGS

(1) The sodium retaining effects of CNIs are mediated by stimulation of the thiazide-sensitive sodium chloride co-transporter in the distal convoluted tubule and in this regard chlorthalidone was proven to be an effective antihypertensive drug in renal transplantation. (2) Local and not systemic activation of the renin-angiotensin-aldosterone system plays a crucial role in the pathogenesis of posttransplant hypertension. (3) Recent randomized controlled trials failed to prove the presumed superiority of renin-angiotensin blockers in kidney transplantation. (4) Steroid-free and mammalian target of rapamycin-based immunosuppressive drug combinations did not show favorable effects on blood pressure control. (5) In a recent report the risk of non-melanoma skin cancer was higher with thiazide diuretics. But the increased cancer risk in transplant recipients is mainly attributed to comorbidities, such as diabetes and hypertension and of course to the transplantation condition itself or the obligatory application of immunosuppression, and has little to do with the antihypertensive medication Actual recommendations about BP targets in adult renal transplant recipients are coming from a post hoc analysis of a large randomized trial with another primary endpoint. Unless convincing studies on treatment of hypertension after renal transplantation are available, the ESC/ESH Guidelines 2018 should apply for these patients.

Blood pressure monitoring in kidney transplantation: a systematic review on hypertension and target organ damage

BACKGROUND

Sparse studies show that ambulatory blood pressure monitoring (ABPM) is superior to office BP (oBP) measurements to predict target organ damage and cardiovascular (CV) events in kidney transplant recipients (KTRs). We performed a systematic review aimed at determining the potential associations between BP recordings by different methods and renal and CV outcomes in this population.

METHODS

Major medical databases were searched for studies enrolling adult KTRs undergoing 24h ABPM compared to office or home BP measurements. Main outcomes were: associations between different BP recordings and renal and CV outcomes. Additionally, any association between the circadian BP pattern (dipping/non-dipping status) and outcomes was assessed.

RESULTS

Twenty-two studies (2078 participants) were reviewed. Amongst 12 studies collecting data on renal endpoints, ten studies found that BP assessed by ABPM was a stronger predictor of renal function decline, assessed by serum creatinine (SCr) and/or creatinine clearance (CrCl) or estimated glomerular filtration rate (eGFR), than traditional office measurements. Twelve studies analyzed the relation between different BP recordings and CV target organ damages and reported robust correlations between echocardiographic abnormalities [i.e. left ventricular mass index (LVM/LVMI)] and 24h ABPM, but not with office BPs. Furthermore, 24h ABPM correlated better than oBP with markers of vascular damage, such as carotid intima-media thickness (IMT), diffuse thickening, and endothelial dysfunction. Additionally, abnormal circadian BP pattern (non-dippers and reverse dippers) identified a group of kidney recipients at risk for kidney function loss and CV abnormalities.

CONCLUSIONS

In our systematic review, ABPM reflected target organ damage more closely than oBP in KTRs. Furthermore, altered circadian BP profile associated with renal and CV target organ damages.

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.

Intensive blood pressure control is associated with improved patient and graft survival after renal transplantation

Based on data of the SPRINT trial, American hypertension guidelines recently reduced the blood pressure goal from 140/90 mmHg to 130/80 mmHg for subjects with chronic kidney disease (CKD), whereas European guidelines recommend a systolic blood pressure (SBP) of 130-139 mmHg. The present analysis investigates whether a SBP < 130 mmHg is associated with an additional benefit in renal transplant recipients. We performed a retrospective analysis of 815 renal transplant recipients who were stratified according to mean office SBP values < 130 mmHg, 130-139 mmHg or ≥140 mmHg. Patient and graft survival was defined as composite endpoint, follow-up was limited to 120 months. Mean SBP of the follow-up was significantly associated with the composite endpoint (n = 218) with better survival for a SBP < 130 mmHg and 130-139 mmHg compared to ≥140 mmHg (p < 0.001). The differences in the combined endpoint remained significant in Cox regression analysis adjusted for age, gender and eGFR (p = 0.007, HR = 0.58, 95%CI = 0.41-0.53), but not for graft survival alone. Renal transplant recipients with SBP < 130 mmHg had a lower mortality than those with the conservative blood pressure goal <140 mmHg. These data suggest that the new AHA BP targets are safe for renal transplant recipients and - with all limitations of a retrospective analysis - might even be associated with improved outcome.

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.

Comparative effectiveness of different antihypertensive agents in kidney transplantation: a systematic review and meta-analysis

Background

We conducted a systematic review and meta-analysis to compare benefits and harms of different antihypertensive drug classes in kidney transplant recipients, as post-transplant hypertension (HTN) associates with increased cardiovascular (CV) morbidity and mortality.

Methods

The Ovid-MEDLINE, PubMed and CENTRAL databases were searched for randomized controlled trials (RCTs) comparing all main antihypertensive agents versus placebo/no treatment, routine treatment.

Results

The search identified 71 RCTs. Calcium channel blockers (CCBs) (26 trials) reduced the risk for graft loss {risk ratio [RR] 0.58 [95% confidence interval (CI) 0.38–0.89]}, increased glomerular filtration rate (GFR) [mean difference (MD) 3.08 mL/min (95% CI 0.38–5.78)] and reduced blood pressure (BP). Angiotensin-converting enzyme inhibitors (ACEIs) (13 trials) reduced the risk for graft loss [RR 0.62 (95% CI 0.40–0.96)] but decreased renal function and increased the risk for hyperkalaemia. Angiotensin receptor blockers (ARBs) (10 trials) did not modify the risk of death, graft loss and non-fatal CV events and increased the risk for hyperkalaemia. When pooling ACEI and ARB data, the risk for graft failure was lower in renin–angiotensin system (RAS) blockade as compared with control treatments. In direct comparison with ACEIs or ARBs (11 trials), CCBs increased GFR [MD 11.07 mL/min (95% CI 6.04–16.09)] and reduced potassium levels but were not more effective in reducing BP. There are few available data on mortality, graft loss and rejection. Very few studies performed comparisons with other active drugs.

Conclusions

CCBs could be the preferred first-step antihypertensive agents in kidney transplant patients, as they improve graft function and reduce graft loss. No definite patient or graft survival benefits were associated with RAS inhibitor use over conventional treatment.