Effects of angiotensin converting enzyme inhibitor and angiotensin II receptor antagonist therapy in hypertensive renal transplant recipients

Effect of angiotensin II type-1 receptor blockers on stable allograft kidneys: prospective randomized study

OBJECTIVE

Is assess the effects of angiotensin II type-I receptor blockers on outcomes in renal transplant recipients without proteinuria or posttransplantation erythrocytosis.

PATIENTS AND METHODS

Fifty renal transplant recipients (30 men and 20 women, with a mean [SD] age of 40 [13] years) were randomized into 2 groups of 25 patients each; 1 group was treated with losartan for 1 year, and the other was not (control group). Blood pressure and other biochemical parameters were measured at baseline and at 6 and 12 months posttransplantation.

RESULTS

After 1 year, the losartan group had significantly lower systolic blood pressure (113 [22] mm Hg vs 126 [18] mm Hg; P = .04) and hemoglobin concentration (12.8 [1.9] g/dL vs 14.5 [2.1] g/dL; P = .006) and significantly higher serum high-density lipoprotein cholesterol concentration (58 [22] mg/dL vs 47 [10] mg/dL; P = .03) compared with the control group; however the incidence of anemia did not differ (37% vs 20%; P = .20). In the losartan group, there were significant changes in hemoglobin concentration between baseline and 6 months (14.5 [1.6] g/dL vs 12.9 [1.49] g/dL; P < .001), but not between 6 and 12 months (12.9 [1.49] g/dL vs 12.8 [1.96] g/dL; P = .43). After 1 year, there were no significant between-group differences in diastolic hypertension, serum creatinine concentration, creatinine clearance, and serum potassium, low-density lipoprotein cholesterol, triglyceride, and uric acid concentrations.

CONCLUSION

Losartan significantly increased high-density lipoprotein concentration and significantly decreased systolic hypertension. Although losartan decreased the hemoglobin concentration during the first 6 months, its effect did not progress with longer use. To determine the effect of losartan on renal function, additional studies with longer follow-up are needed.

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.

Urinary albumin excretion in patients with diabetes after renal transplantation

BACKGROUND

Many studies support microalbuminuria screening as the cornerstone of early detection of nephropathy in patients with diabetes mellitus (DM), but there are no studies that address its utility in the follow-up of renal transplant recipients with DM.

MATERIALS AND METHODS

We retrospectively studied 104 subjects with DM who had undergone renal transplantation. Sixty three had a history of preexisting DM and 41 developed posttransplant diabetes (PTDM). We collected data on random urine albumin/creatinine (A/C) ratio, systolic blood pressure (SBP), serum creatinine concentration (Cr), and HBA1C.

RESULTS

Mean subject age was 58 +/- 9.8 years; 63% received cadaveric grafts while 37% received living donor grafts. Mean follow-up was 7 years (range 1.6 to 15.6). Seventy percentage developed proteinuria over time; of these 62% developed microalbuminuria (A/C ratio 30 to 300 microg albumin/mg creatinine) and 38% developed macroalbuminuria (A/C ratio >300 microg/mg). Subjects with preexisting DM were as likely to develop an elevated A/C ratio as those with PTDM. Higher A/C ratios correlated with higher SBP (P < .01), with higher HBA1C (P < .036), and with higher Cr (P < .01). Lower A/C ratios correlated with more stable Cr over time (P < .01).

CONCLUSIONS

Strict SBP and glycemic control are associated with a significantly lower A/C ratio in patients with DM after renal transplantation. Annual monitoring of A/C ratio in patients with DM after renal transplantation can identify candidates for stricter glycemic and blood pressure control, similar to current recommendations for all other patients with DM.

Anemia Due to Losartan in Hypertensive Renal Transplant Recipients Without Posttransplant Erythrocytosis

Losartan is a safe, effective long-term treatment for hypertension or posttransplant erythrocytosis (PTE) in renal transplant recipients. There were only a few studies in patients without PTE and their results were different. Starting from week 6 and continuing to the week 12 we observed a decrease in hemoglobin (Hb) and hematocrit (Hct) levels in patients without PTE. Anemia developed in 42.8% of the patients, and Hb levels increased after the withdrawal of losartan treatment. There was a significant decrease in Hct levels beginning from week 3 when compared with the control group. Our study suggests that losartan therapy can decrease Hb beyond its antihypertensive efficacy. Based on the capacity of losartan to decrease Hb and Hct, this drug should be carefully used in patients with preexistent anemia or low Hb levels.

Effect of angiotensin II receptor blocker on plasma levels of TGF-beta 1 and interstitial fibrosis in hypertensive kidney transplant patients

BACKGROUND/AIM

Transforming growth factor-beta1 (TGF-beta 1) is involved in the pathogenesis of chronic allograft nephropathy after kidney transplantation. The aim of the study was to evaluate the effect of the angiotensin receptor blocker losartan on TGF-beta 1 plasma levels and proteinuria in hypertensive transplant recipients.

METHODS

A total of 162 transplant recipients were included in the study. The patients were randomized into 3 groups: group 1 received losartan; group II received an angiotensin-converting enzyme inhibitor (captopril), and group III received a calcium channel blocker (amlodipine). All the parameters were recorded at the time of therapy initiation and at 1, 4 and 12 weeks and 12 months thereafter. Graft biopsy before the start and at the end of the study was done to evaluate histopathological progression.

RESULTS

Blood pressure was controlled in the 3 groups; however, the need for other antihypertensive agents was significant in groups I and II. Treatment with losartan significantly decreased the plasma level of TGF-beta1, 24-hour urinary protein and serum uric acid (p < 0.05). No significant changes were seen in the hemoglobin or serum potassium levels. The rate of histopathological progression was significantly lower in the losartan group. No patient was discharged from the study due to side effects.

CONCLUSIONS

After transplantation all drugs were able to control blood pressure with good safety and tolerability. The study demonstrates that ARB significantly decreases the plasma levels of TGF-beta1, proteinuria and uric acid. These results could play an important and decisive role in the treatment and prevention of chronic allograft nephropathy.