Nifedipine improves immediate, and 6- and 12-month graft function in cyclosporin A (CyA) treated renal allograft recipients

Antihypertensive treatment for kidney transplant recipients

BACKGROUND

In some nontransplant populations, effects of different antihypertensive drug classes vary. Relative effects in kidney transplant recipients are uncertain.

OBJECTIVES

To assess comparative effects of different classes of antihypertensive agents in kidney transplant recipients.

SEARCH STRATEGY

MEDLINE, EMBASE, the Cochrane Central Register of Controlled Trials, conference proceedings and reference lists of identified studies were searched.

SELECTION CRITERIA

Randomised controlled trials of any antihypertensive agent applied to kidney transplant recipients for at least two weeks were included.

DATA COLLECTION AND ANALYSIS

Data was extracted by two investigators independently. Study quality, transplant outcomes and other patient centred outcomes were assessed using random effects meta-analysis. Risk ratios (RR) for dichotomous outcomes and mean difference (MD) for continuous outcomes, both with 95% confidence intervals (CI) were calculated. Stratified analyses and meta-regression were used to investigate heterogeneity.

MAIN RESULTS

We identified 60 studies, enrolling 3802 recipients. Twenty-nine studies (2262 participants) compared calcium channel blockers (CCB) to placebo/no treatment, 10 studies (445 participants) compared angiotensin converting enzyme inhibitors (ACEi) to placebo/no treatment and seven studies (405 participants) compared CCB to ACEi. CCB compared to placebo/no treatment (plus additional agents in either arm as required) reduced graft loss (RR 0.75, 95% CI 0.57 to 0.99) and improved glomerular filtration rate (GFR), (MD, 4.45 mL/min, 95% CI 2.22 to 6.68). Data on ACEi versus placebo/no treatment were inconclusive for GFR (MD -8.07 mL/min, 95% CI -18.57 to 2.43), and variable for graft loss, precluding meta-analysis. In direct comparison with CCB, ACEi decreased GFR (MD -11.48 mL/min, 95% CI -5.75 to -7.21), proteinuria (MD -0.28 g/24 h, 95% CI -0.47 to -0.10), haemoglobin (MD -12.96 g/L, 95% CI -5.72 to -10.21) and increased hyperkalaemia (RR 3.74, 95% CI 1.89 to 7.43). Graft loss data were inconclusive (RR 7.37, 95% CI 0.39 to 140.35). Other drug comparisons were compared in small numbers of participants and studies.

AUTHORS' CONCLUSIONS

These data suggest that CCB may be preferred as first line agents for hypertensive kidney transplant recipients. ACEi have some detrimental effects in kidney transplant recipients. More high quality studies reporting patient centred outcomes are required.

Calcium channel blockers for preventing acute tubular necrosis in kidney transplant recipients

BACKGROUND

The incidence of delayed graft function in cadaveric grafts has increased over the last few years due in part to the large demand for cadaveric kidneys necessitating the use of kidneys from marginal donors. Calcium channel blockers have the potential to reduce the incidence of post-transplant acute tubular necrosis (ATN) if given in the peri-operative period. However, there is controversy surrounding their use in this situation with no consensus as to their efficacy.

OBJECTIVES

To evaluate the benefits and harms of using calcium channel blockers in the peri-transplant period in patients at risk of ATN following cadaveric kidney transplantation.

SEARCH STRATEGY

We searched the Cochrane Renal Group's specialised register, the Cochrane Central Register of Controlled Trials (CENTRAL, in The Cochrane Library) MEDLINE (from 1966) and EMBASE (from 1980). The Trials Search Coordinator was contacted to develop the search strategy. Date of last search: January 2007

SELECTION CRITERIA

Randomised controlled trials comparing calcium channel blockers given in the peri-transplant period with controls were included. Quasi-randomised trials were excluded.

DATA COLLECTION AND ANALYSIS

Data was extracted and quality assessed independently by two reviewers, with differences resolved by discussion. Dichotomous outcomes are reported as relative risk (RR) and measurements on continuous scales are reported as mean differences (WMD) with 95% confidence intervals (CI).

MAIN RESULTS

Thirteen trials (724 participants) were suitable for inclusion. Treatment with calcium channel blockers in the peri-transplant period was associated with a significant decrease in the incidence of post-transplant ATN (RR 0.62, 95% CI 0.46 to 0.85) and delayed graft function (RR 0.55, 95% CI 0.42 to 0.73). There was no difference between control and treatment groups in graft loss, mortality, requirement for haemodialysis. There was insufficient information to comment on adverse events.

AUTHORS' CONCLUSIONS

These results suggest that calcium channel blockers given in the peri-operative period may reduce the incidence of ATN post-transplantation. The result should be treated with caution due to the heterogeneity of the trials which made comparison of studies and pooling of data difficult.

Influence of nifedipine on interstitial fibrosis in renal transplant allografts treated with cyclosporin A

AIMS

To compare the degree of interstitial fibrosis in renal transplant biopsy specimens from immunosuppressed patients using conventional doses of cyclosporin with and without calcium channel blockade with a combination of low dose cyclosporin and azathioprine; to correlate the degree of interstitial fibrosis with the glomerular filtration rate.

METHODS

A single blind histomorphometric assessment was done of cortical interstitial volume fraction from biopsy specimens taken intraoperatively and at one, six, and 12 months after transplantation from three prospectively randomised groups of patients: (A) conventional dose cyclosporin; (B) conventional dose cyclosporin plus nifedipine; (C) low dose cyclosporin plus azathioprine.

RESULTS

Interstitial volume increased with time in all groups. No differences in interstitial volume were present at operation or at one month, but at six months interstitial volume was significantly less in group B than group A (p < 0.001) or group C (p < 0.05). More grafts failed in group A than group B leaving only small numbers for comparison at 12 months. At 12 months the differences persisted but did not reach significance. These results strongly reflected the clinical findings, where glomerular filtration rate was significantly lower in group A than groups B or C at six and 12 months; no differences in glomerular filtration rate were found at one month. In a direct comparison glomerular filtration rate showed a significant negative correlation with interstitial volume fraction.

CONCLUSIONS

These findings suggest that calcium channel blockade with nifedipine slows the development of interstitial fibrosis in renal transplant recipients treated with cyclosporin. When clinical data are considered, it is suggested that calcium channel blockade may have a mitigating effect on the long term nephrotoxic effects of cyclosporin and should be considered as adjunctive treatment in patients requiring this immunosuppressant following renal transplantation.