Optimizing hypertension management in renal transplantation: a call to action

Antihypertensive treatment for kidney transplant recipients

BACKGROUND

The comparative effects of specific blood pressure (BP) lowering treatments on patient-important outcomes following kidney transplantation are uncertain. Our 2009 Cochrane review found that calcium channel blockers (CCBs) improved graft function and prevented graft loss, while the evidence for other BP-lowering treatments was limited. This is an update of the 2009 Cochrane review.

OBJECTIVES

To compare the benefits and harms of different classes and combinations of antihypertensive drugs in kidney transplant recipients.

SEARCH METHODS

We contacted the Information Specialist and searched the Cochrane Kidney and Transplant Register of Studies up to 3 July 2024 using search terms relevant to this review. Studies in the Register were identified through searches of CENTRAL, MEDLINE, EMBASE, conference proceedings, the International Clinical Trials Registry Platform (ICTRP) Search Portal, and ClinicalTrials.gov.

SELECTION CRITERIA

Randomised controlled trials (RCTs) and quasi-RCTs evaluating any BP-lowering agent in recipients of a functioning kidney transplant for at least two weeks were eligible.

DATA COLLECTION AND ANALYSIS

Two authors independently assessed the risks of bias and extracted data. Treatment estimates were summarised using the random-effects model and expressed as relative risk (RR) or mean difference (MD) with 95% confidence intervals (CI). Evidence certainty was assessed using Grades of Recommendation, Assessment, Development and Evaluation (GRADE) processes. The primary outcomes included all-cause death, graft loss, and kidney function.

MAIN RESULTS

Ninety-seven studies (8706 participants) were included. One study evaluated treatment in children. The overall risk of bias was unclear to high across all domains. Compared to placebo or standard care alone, CCBs probably reduce all-cause death (23 studies, 3327 participants: RR 0.83, 95% CI 0.72 to 0.95; I2 = 0%; moderate certainty evidence) and graft loss (24 studies, 3577 participants: RR 0.84, 95% CI 0.75 to 0.95; I2 = 0%; moderate certainty evidence). CCBs may make little or no difference to estimated glomerular filtration rate (eGFR) (11 studies, 2250 participants: MD 1.89 mL/min/1.73 m2, 95% CI -0.70 to 4.48; I2 = 48%; low certainty evidence) and acute rejection (13 studies, 906 participants: RR 10.8, 95% CI 0.85 to 1.35; I2 = 0%; moderate certainty evidence). CCBs may reduce systolic BP (SBP) (3 studies, 329 participants: MD -5.83 mm Hg, 95% CI -10.24 to -1.42; I2 = 13%; low certainty evidence) and diastolic BP (DBP) (3 studies, 329 participants: MD -3.98 mm Hg, 95% CI -5.98 to -1.99; I2 = 0%; low certainty evidence). CCBs have uncertain effects on proteinuria. Compared to placebo or standard care alone, angiotensin-converting-enzyme inhibitors (ACEi) may make little or no difference to all-cause death (7 studies, 702 participants: RR 1.13, 95% CI 0.58 to 2.21; I2 = 0%; low certainty evidence), graft loss (6 studies, 718 participants: RR 0.75, 95% CI 0.49 to 1.13; I2 = 0%; low certainty evidence), eGFR (4 studies, 509 participants: MD -2.46 mL/min/1.73 m2, 95% CI -7.66 to 2.73; I2 = 64%; low certainty evidence) and acute rejection (4 studies, 388 participants: RR 1.75, 95% CI 0.76 to 4.04; I2 = 0%; low certainty evidence). ACEi may reduce proteinuria (5 studies, 441 participants: MD -0.33 g/24 hours, 95% CI -0.64 to -0.01; I2 = 67%; low certainty evidence) but had uncertain effects on SBP and DBP. Compared to placebo or standard care alone, angiotensin receptor blockers (ARB) may make little or no difference to all-cause death (6 studies, 1041 participants: RR 0.69, 95% CI 0.36 to 1.31; I2 = 0%; low certainty evidence), eGRF (5 studies, 300 participants: MD -1.91 mL/min/1.73 m2, 95% CI -6.20 to 2.38; I2 = 57%; low certainty evidence), and acute rejection (4 studies, 323 participants: RR 1.00, 95% CI 0.44 to 2.29; I2 = 0%; low certainty evidence). ARBs may reduce graft loss (6 studies, 892 participants: RR 0.35, 95% CI 0.15 to 0.84; I2 = 0%; low certainty evidence), SBP (10 studies, 1239 participants: MD -3.73 mm Hg, 95% CI -7.02 to -0.44; I2 = 63%; moderate certainty evidence) and DBP (9 studies, 1086 participants: MD -2.75 mm Hg, 95% CI -4.32 to -1.18; I2 = 47%; moderate certainty evidence), but has uncertain effects on proteinuria. The effects of CCBs, ACEi or ARB compared to placebo or standard care alone on cardiovascular outcomes (including fatal or nonfatal myocardial infarction, fatal or nonfatal stroke) or other adverse events were uncertain. The comparative effects of ACEi plus ARB dual therapy, alpha-blockers, and mineralocorticoid receptor antagonists compared to placebo or standard care alone were rarely evaluated. Head-to-head comparisons of ACEi, ARB or thiazide versus CCB, ACEi versus ARB, CCB or ACEi versus alpha- or beta-blockers, or ACEi plus CCB dual therapy versus ACEi or CCB monotherapy were scarce. No studies reported outcome data for cancer or life participation.

AUTHORS' CONCLUSIONS

For kidney transplant recipients, the use of CCB therapy to reduce BP probably reduces death and graft loss compared to placebo or standard care alone, while ARB may reduce graft loss. The effects of ACEi and ARB compared to placebo or standard care on other patient-centred outcomes were uncertain. The effects of dual therapy, alpha-blockers, and mineralocorticoid receptor antagonists compared to placebo or standard care alone and the comparative effects of different treatments were uncertain.

Diagnostic Performance of Office versus Ambulatory Blood Pressure in Kidney Transplant Recipients

INTRODUCTION

Hypertension is the most prominent risk factor in kidney transplant recipients (KTRs). No study so far assessed in parallel the prevalence, control, and phenotypes of blood pressure (BP) or the accuracy of currently recommended office BP diagnostic thresholds in diagnosing elevated ambulatory BP in KTRs.

METHODS

205 stable KTRs underwent office BP measurements and 24-h ambulatory BP monitoring (ABPM). Hypertension was defined as follows: (1) office BP ≥140/90 mm Hg or use of antihypertensive agents following the current European Society of Cardiology/European Society of Hypertension (ESC/ESH) guidelines, (2) office BP ≥130/80 mm Hg or use of antihypertensive agents following the current American College of Cardiology/American Heart Association (ACC/AHA) guidelines, (3) ABPM ≥130/80 mm Hg or use of antihypertensive agents, and (4) ABPM ≥125/75 mm Hg or use of antihypertensive agents.

RESULTS

Hypertension prevalence by office BP was 88.3% with ESC/ESH and 92.7% with ACC/AHA definitions compared to 94.1 and 98.5% at relevant ABPM thresholds. Control rates among hypertensive patients were 69.6 and 43.7% with office BP compared to 38.3 and 21.3% with ABPM, respectively. Both for prevalence (κ-statistics = 0.52, p < 0.001 and 0.32, and p < 0.001) and control rates (κ-statistics = 0.21, p < 0.001 and 0.22, and p < 0.001, respectively), there was moderate or fair agreement of the 2 techniques. White-coat and masked hypertension were diagnosed in 6.7 and 39.5% of patients at the 140/90 threshold and 5.9 and 31.7% of patients at the 130/80 threshold. An office BP ≥140/90 mm Hg had 35.3% sensitivity and 84.9% specificity for the diagnosis of 24-h BP ≥130/80 mm Hg. An office BP ≥130/80 mm Hg had 59.7% sensitivity and 73.9% specificity for the diagnosis of 24-h BP ≥125/75 mm Hg. Receiver operating curve analyses confirmed this poor diagnostic performance.

CONCLUSIONS

At both corresponding thresholds studied, ABPM revealed particularly high hypertension prevalence and poor BP control in KTRs. Misclassification of KTRs by office BP is substantial, due to particularly high rates of masked hypertension. The diagnostic accuracy of office BP for identifying elevated ambulatory BP is poor. These findings call for a wider use of ABPM in KTRs.

Long-term blood pressure monitoring by office and 24-h ambulatory blood pressure in renal transplant patients: a longitudinal study

Background

Renal transplant patients have a high prevalence of nocturnal hypertension, and hypertension misclassification by office blood pressure (BP) is quite common in these patients. The potential impact of hypertension misclassification by office BP on hypertension management in this population has never been analysed.

Methods

We performed a longitudinal study in a cohort of 260 clinically stable renal transplant patients. In all, 785 paired office and 24-h ambulatory blood pressure monitoring (24-hABPM) measurements over a median follow-up of 3.9 years were available in the whole cohort.

Results

A total of 74% of patients had nocturnal hypertension (&gt;120/70 mmHg). Average office BP and 24-hABPM remained quite stable over follow-up, as did the prevalence of nocturnal hypertension, which was 77% at the last observation. However, the global agreement between office BP and average 24 h, daytime and night-time BP was unsatisfactory (k-statistics 0.10–0.26). In 193 visits (25% of all visits) where office BP indicated the need of antihypertensive therapy institution or modification (BP &gt;140/90 mmHg), 24-hABPM was actually normal (&lt;130/80 mmHg), while in 94 visits (12%), 24-hABPM was in the hypertensive range while office BP was normal. Overall, in 37% of visits, office BP provided misleading therapeutic indications.

Conclusions

Hypertension misclassification by office BP is a common phenomenon in stable renal transplant patients on long-term follow-up. Office BP may lead to inappropriate therapeutic decisions in over one-third of follow-up visits in these patients.