Zhongxin Zhang

Albuminuria, a Therapeutic Target for Cardiovascular Protection in Type 2 Diabetic Patients With Nephropathy

Background—Albuminuria is an established risk marker for both cardiovascular and renal outcomes. Albuminuria can be reduced with drugs that block the renin-angiotensin system (RAS). We questioned whether the short-term drug-induced change in albuminuria would predict the long-term cardioprotective efficacy of RAS intervention. Methods and Results—We analyzed data from Reduction in Endpoints in Non–insulin dependent diabetes mellitus with the Angiotensin II Antagonist Losartan (RENAAL), a double-blind, randomized trial in 1513 type 2 diabetic patients with nephropathy, focusing on the relationship between the prespecified cardiovascular end point (composite) or hospitalization for heart failure and baseline or reduction in albuminuria. Patients with high baseline albuminuria (≥3 g/g creatinine) had a 1.92-fold (95% CI, 1.54 to 2.38) higher risk for the cardiovascular end point and a 2.70-fold (95% CI, 1.94 to 3.75) higher risk for heart failure compared with patients with low albuminuria (<1.5 g/g). Among all available baseline risk markers, albuminuria was the strongest predictor of cardiovascular outcome. The association between albuminuria and cardiovascular outcome was driven by those patients who also had a renal event. Modeling of the initial 6-month change in risk parameters showed that albuminuria reduction was the only predictor for cardiovascular outcome: 18% reduction in cardiovascular risk for every 50% reduction in albuminuria and a 27% reduction in heart failure risk for every 50% reduction in albuminuria. Conclusions—Albuminuria is an important factor predicting cardiovascular risk in patients with type 2 diabetic nephropathy. Reducing albuminuria in the first 6 months appears to afford cardiovascular protection in these patients.

Albuminuria Is a Target for Renoprotective Therapy Independent from Blood Pressure in Patients with Type 2 Diabetic Nephropathy: Post Hoc Analysis from the Reduction of Endpoints in NIDDM with the Angiotensin II Antagonist Losartan (RENAAL) Trial

Albuminuria reduction could be renoprotective in hypertensive patients with diabetic nephropathy. However, the current use of renin-angiotensin-system intervention is targeted to BP only. Therefore, this study investigated the adequacy of this approach in 1428 patients with hypertension and diabetic nephropathy from the placebo-controlled Reduction of Endpoints in NIDDM with the Angiotensin II Antagonist Losartan (RENAAL) study. Investigated were the extent of discordance in treatment effects on systolic BP (SBP) and albuminuria and its association with renal outcome in a multivariate Cox model. Among patients with a reduced SBP during treatment, a lack of albuminuria reduction was observed in 37, 26, and 51% (total, losartan, and placebo, respectively) at month 6. SBP or albuminuria reduction was associated with a lower risk for ESRD, whereas combined SBP and albuminuria reduction was associated with the lowest risk for events. Across all categories of SBP change, a progressively lower ESRD hazard ratio was observed with a larger albuminuria reduction. A lower residual level of albuminuria was also associated with lower ESRD risk. In conclusion, changes in albuminuria are not concordant in a substantial proportion of patients when titrated for BP. Meanwhile, the ESRD risk showed a clear dependence on albuminuria reduction. The ESRD risk also showed dependence on the residual level of albuminuria, even in patients who reached the current SBP target. Antihypertensive treatment that is aimed at improving renal outcomes in patients with diabetic nephropathy may therefore require a dual strategy, targeting both SBP and albuminuria reduction.

Risk Scores for Predicting Outcomes in Patients with Type 2 Diabetes and Nephropathy: The RENAAL Study

Diabetic nephropathy is the most important cause of ESRD. The aim of this study was to develop a risk score from risk predictors for ESRD, with and without death, in the Reduction of Endpoints in NIDDM with the Angiotensin II Antagonist Losartan (RENAAL) study and to compare ability of the ESRD risk score and its components to predict ESRD. The risk score was developed from coefficients of independent risk factors from multivariate analysis of baseline variables and equals (1.96 x log [urinary albumin:creatinine ratio]) - (0.78 serum albumin [g/dl]) + (1.28 x serum creatinine [mg/dl]) - (0.11 x hemoglobin [g/dl]). It was robust with respect to severity of nephropathy, gender, race, and treatment group. The risk score for ESRD or death was comparable. The four risk predictors for progression of kidney disease were independent of therapy. For combined treatment groups, the hazard ratio between the fourth and first quartiles of the ESRD risk score was 49.0, as compared with the corresponding hazard ratios for each component: 14.7 for urinary albumin:creatinine ratio, 9.2 for serum creatinine, 5.5 for hemoglobin, and 10.2 for serum albumin. The RENAAL risk scores for ESRD with or without death emphasize the importance of identification of level of albuminuria, serum albumin, serum creatinine, and hemoglobin to predict development of ESRD in patients with type 2 diabetes and nephropathy. Although albuminuria is a strong risk factor for ESRD, the contribution of serum albumin, serum creatinine, and hemoglobin level further enhances prediction of ESRD. Future trials with a similar patient population and outcomes measures should consider adjusting analyses for baseline risk factors.

The losartan renal protection study — rationale, study design and baseline characteristics of RENAAL (Reduction of Endpoints in NIDDM with the Angiotensin II Antagonist Losartan)

The RENAAL Study is a double-blind, placebo-controlled trial to evaluate the renal protective effects of losartan in Type 2 diabetic patients with nephropathy. The study has enrolled 1513 patients and is expected to continue for 3.5 years after the last patient has been entered. Eligible patients must have a urinary albumin:creatinine ratio of at least 300 mg/g and serum creatinine between 1.3 to 3.0 mg/dL. Eligible hypertensive or normotensive patients are randomised to receive either losartan or placebo, in addition to their existing antihypertensive therapy. Medications that block angiotensin production or action, are excluded. The primary endpoint is a composite of the time to first event of doubling of serum creatinine, end-stage renal disease, or death; secondary endpoints include cardiovascular events, progression of renal disease, and changes in proteinuria; tertiary endpoints include quality of life, healthcare resource utilisation, and amputations. Patients include Caucasians (48.6%), Blacks (15.2%), Asians (16.7%), and Hispanics (18.2%). Baseline urinary albumin:creatinine ratio and serum creatinine levels average 1867 mg/g and 1.9 mg/dL, respectively. Mean systolic and diastolic blood pressures are 153 and 82 mmHg, respectively. RENAAL will document whether blockade of the AII receptor with losartan produces clinical benefits in patients with Type 2 diabetes and nephropathy.

A Double‐Blind, Placebo‐Controlled, Dose‐Response Study of the Effectiveness and Safety of Enalapril for Children with Hypertension

Despite widespread use to treat childhood hypertension, enalapril has never been studied systematically to determine effectiveness, dose response, and safety in a pediatric population. This study was conducted prospectivelyin 110hypertensive children ages 6 to 16 years in two sequential phases. The primary outcome variable for both phases of the study was trough (24‐h postdose) sitting diastolic blood pressure. The primary objective of the first phase of the study was to determine whether enalapril lowered blood pressure in children in a dose‐dependent manner. During a 2‐week, double‐blind, randomized, dose‐response period, patients were stratified by weight (< 50 kg or ≥50 kg), then assigned to one of three dosing groups: low (0.625 or 1.25 mg), middle (2.5 or 5 mg), or high dose (20 or 40 mg). Reduction in blood pressure was examined as a function of dose ratio (1:4:32) and on a weight‐adjusted basis. On completion of the dose‐response phase of the study, patients entered a 2‐week, double‐blind, randomized withdrawal to either enalapril or placebo. Antihypertensive effectiveness, defined as the difference in sitting diastolic blood pressure between the placebo and enalapril groups, was determined. Adverse events were carefully recorded throughout the study. The dose‐response relationship for enalapril had a negative slope and was linear over the chosen dosingrange, suggesting that larger doses of enalapril were associated with a greater reduction in blood pressure. Randomized withdrawal to active drug or placebo confirmed the antihypertensive effectiveness of enalapril in the middle‐ and high‐dose groups. The antihypertensive effect of enalapril was maintained across age, gender, race, and Tanner stage. Enalapril appears to be an effective and generally well‐tolerated antihypertensive agent in children ages 6 to 16 years. An initial dose of 2.5 mg in children weighing < 50 kg and 5 mg in children weighing ≥50 kg (mean = 0.08 mg/kg) administered once daily effectively lowered blood pressure within 2 weeks in most patients. Blood pressure was reduced in a dose‐dependent fashion, with larger doses resulting in a greater reduction.

A Double-Blind, Placebo-Controlled, Dose-Response Study of the Effectiveness and Safety of Lisinopril for Children With Hypertension

BACKGROUND Despite widespread use in hypertensive children, the safety and effectiveness of lisinopril had not been previously tested in a controlled study. METHODS This study explored the dose-response relationship and safety of lisinopril in 115 hypertensive children, aged 6 to 16 years. Patients were randomized in a double-blind fashion for 2 weeks to one of three doses by body weight at baseline: <50 kg: low (0.625 mg), middle (2.5 mg), high (20 mg), and > or =50 kg: low (1.25 mg), middle (5 mg), high (40 mg). The dose-response for lisinopril was evaluated by analyzing the change in slope in sitting diastolic and systolic blood pressure (BP) by dose after 2 weeks of therapy compared to baseline. Patients then entered a double-blind withdrawal, where patients were either switched to placebo or continued their current lisinopril treatment for up to 2 weeks. Patients completed period II when their BP returned to baseline. Antihypertensive effectiveness, between placebo and lisinopril was determined for all doses. Adverse events were carefully monitored. RESULTS There was a dose-response relationship between the lowest and each of the higher doses of lisinopril. Blood pressure in the placebo group increased after withdrawal of lisinopril. The dose-response relationship was consistent across all subgroups (ie, age, Tanner stage, ethnicity, gender). CONCLUSIONS Lisinopril, once daily, is an effective and well-tolerated antihypertensive in children aged 6 to 16 years. An initial dose of 0.07 mg/kg, administered once daily, effectively lowered BP within 2 weeks. Blood pressure was reduced in a dose-dependent fashion.

Risk scores for predicting outcomes in patients with type 2 diabetes and nephropathy: The RENAAL study

Diabetic nephropathy is the most important cause of ESRD. The aim of this study was to develop a risk score from risk predictors for ESRD, with and without death, in the Reduction of Endpoints in NIDDM with the Angiotensin II Antagonist Losartan (RENAAL) study and to compare ability of the ESRD risk score and its components to predict ESRD. The risk score was developed from coefficients of independent risk factors from multivariate analysis of baseline variables and equals (1.96 x log [urinary albumin:creatinine ratio]) - (0.78 serum albumin [g/dl]) + (1.28 x serum creatinine [mg/dl]) - (0.11 x hemoglobin [g/dl]). It was robust with respect to severity of nephropathy, gender, race, and treatment group. The risk score for ESRD or death was comparable. The four risk predictors for progression of kidney disease were independent of therapy. For combined treatment groups, the hazard ratio between the fourth and first quartiles of the ESRD risk score was 49.0, as compared with the corresponding hazard ratios for each component: 14.7 for urinary albumin:creatinine ratio, 9.2 for serum creatinine, 5.5 for hemoglobin, and 10.2 for serum albumin. The RENAAL risk scores for ESRD with or without death emphasize the importance of identification of level of albuminuria, serum albumin, serum creatinine, and hemoglobin to predict development of ESRD in patients with type 2 diabetes and nephropathy. Although albuminuria is a strong risk factor for ESRD, the contribution of serum albumin, serum creatinine, and hemoglobin level further enhances prediction of ESRD. Future trials with a similar patient population and outcomes measures should consider adjusting analyses for baseline risk factors.

Importance of Baseline Distribution of Proteinuria in Renal Outcomes Trials: Lessons from the Reduction of Endpoints in NIDDM with the Angiotensin II Antagonist Losartan (RENAAL) Study

A key issue in the analysis of outcome trials is the adjustment for baseline covariates that influence the primary outcome. Imbalance of an important covariate between treatment groups at baseline is of considerable concern if one treatment group is favored over another with respect to the hypothesis testing outcome. With the use of the Reduction of Endpoints in NIDDM with the Angiotensin II Antagonist Losartan (RENAAL) study database as an example, the influence of baseline proteinuria on the primary composite endpoint, ESRD, and ESRD or death after adjusting for baseline proteinuria as a continuous covariate was examined. Increasing baseline proteinuria was associated with increased risk for renal events, confirming that proteinuria is an important covariate for renal outcomes. When the randomization was stratified according proteinuria <2000 mg/g or >/=2000 mg/g, within the higher proteinuria stratum (>/=2000 mg/g), patients in the losartan group had a higher baseline mean proteinuria value. When the imbalance was adjusted, an increase in the magnitude and the significance of the risk reduction with losartan for each outcome was observed. No apparent interaction between treatment effect and baseline proteinuria was found, and there was no heterogeneity in the treatment response in patients with different baseline proteinuria levels. After proteinuria was adjusted as a continuous variable, greater treatment effects were observed in the RENAAL study. This effect was due solely to the imbalance in baseline proteinuria. Considering the importance of proteinuria as a risk factor, adjustment for baseline proteinuria as a continuous covariate should be prespecified in the design and analysis of clinical trials involving renal outcomes, even when patients are stratified on the basis of level of proteinuria.

Renal function and risk for cardiovascular events in type 2 diabetic patients with hypertension : the RENAAL and LIFE studies.

Objective To investigate whether a threshold exists for cardiovascular risk in type 2 diabetic patients with hypertension, the association between renal function and cardiovascular risk was examined across the entire physiological range of serum creatinine. Design and methods The RENAAL and LIFE studies enrolled 1513 and 1195 patients with type 2 diabetes and hypertension, respectively. The relationship between baseline serum creatinine and the risk for a composite outcome of myocardial infarction, stroke or cardiovascular death was examined using Cox regression models. To adjust for heterogeneity between studies and treatment groups, these factors were included as strata when applicable. The analyses were conducted with adjustment for age, gender, smoking, alcohol use, blood pressure, heart rate, total and high-density lipoprotein (HDL) cholesterol, hemoglobin, albuminuria and prior cardiovascular disease. Results The hazard ratios across the baseline serum creatinine categories < 0.9 mg/dl, 0.9–1.2 mg/dl, 1.2–1.6 mg/dl, 1.6–2.8 mg/dl and ≥ 2.8 mg/dl were 0.51 (95% confidence interval 0.34, 0.74), 0.74 (0.55, 1.00), 1.00 (reference), 1.24 (0.96, 1.59) and 1.67 (1.17, 2.91), respectively. Baseline serum creatinine (per mg/dl) strongly predicted the composite cardiovascular endpoint in LIFE [2.82(1.74,4.56), P < 0.001], RENAAL [1.41(1.12,1.79), P < 0.001], as well as the combined studies [1.51(1.21,1.87), P < 0.001]. Conclusion A progressively higher risk for the composite cardiovascular endpoint was observed with incremental baseline serum creatinine in type 2 diabetic patients with hypertension, even within the normal range. Thus, there appears to be no serum creatinine threshold level for an increased cardiovascular risk. Baseline serum creatinine was a major independent risk factor for cardiovascular disease (www.ClinicalTrials.gov number NCT00308347).

Renin angiotensin aldosterone system blockade and renal disease in patients with type 2 diabetes: a subanalysis of Japanese patients from the RENAAL study

BackgroundThe Reduction of Endpoints in NIDDM with the Angiotensin II Antagonist Losartan (RENAAL) study has previously shown losartan to confer significant benefits to patients with type 2 diabetes and nephropathy. The original study of 1513 patients included 96 Japanese patients; the present study is a post-hoc analysis of the effects of losartan in this Japanese subpopulation.MethodsThis double-blind, randomized study compared losartan (50 to 100 mg once daily) with placebo. The study medication was taken in addition to conventional antihypertensive treatment, and the mean follow-up period for the Japanese patients was 2.8 years. The primary endpoint was the composite of doubling of serum creatinine, endstage renal disease, or death. Secondary endpoints included changes in proteinuria levels. Safety was also evaluated.ResultsThe primary composite endpoint was reached in fewer Japanese patients receiving losartan than placebo (50.0% versus 65.4%, respectively). The treatment effects of losartan were more robust when data were corrected for differences in proteinuria at baseline – a significant relative risk reduction of 45% with losartan (P = 0.0397) was apparent. Treatment benefit exceeded that attributable to blood pressure changes alone. Levels of proteinuria were reduced with losartan compared with placebo, with an overall losartan treatment effect of 37.8% (P < 0.001). Overall, losartan was similarly well tolerated in both the Japanese patients and the total population.ConclusionsIn Japanese patients with type 2 diabetes and nephropathy, losartan offers renal protection and is generally well tolerated.