Medline ® Abstracts for References 103-106

BACKGROUND: Recent guidelines suggest lowering the target blood pressure for patients with chronic kidney disease, although the strength of evidence for this suggestion has been uncertain. We sought to assess the renal and cardiovascular effects of intensive blood pressure lowering in people with chronic kidney disease.

METHODS: We performed a systematic review and meta-analysis of all relevant reports published between 1950 and July 2011 identified in a search of MEDLINE, Embase and the Cochrane Library. We included randomized trials that assigned patients with chronic kidney disease to different target blood pressure levels and reported kidney failure or cardiovascular events. Two reviewers independently identified relevant articles and extracted data.

RESULTS: We identified 11 trials providing information on 9287 patients with chronic kidney disease and 1264 kidney failure events (defined as either a composite of doubling of serum creatinine level and 50% decline in glomerular filtration rate, or end-stage kidney disease). Compared with standard regimens, a more intensive blood pressure-lowering strategy reduced the risk of the composite outcome (hazard ratio [HR]0.82, 95% confidence interval [CI]0.68-0.98) and end-stage kidney disease (HR 0.79, 95% CI 0.67-0.93). Subgroup analysis showed effect modification by baseline proteinuria (p = 0.006) and markers of trial quality. Intensive blood pressure lowering reduced the risk of kidney failure (HR 0.73, 95% CI 0.62-0.86), but not in patients without proteinuria at baseline (HR 1.12, 95% CI 0.67-1.87). There was no clear effect on the risk of cardiovascular events or death.

INTERPRETATION: Intensive blood pressure lowering appears to provide protection against kidney failure events in patients with chronic kidney disease, particularly among those with proteinuria. More data are required to determine the effects of such a strategy among patients without proteinuria.

BACKGROUND: The optimal blood pressure target in patients with chronic kidney disease (CKD) is unclear.

PURPOSE: To summarize trials comparing lower versus higher blood pressure targets in adult patients with CKD and focus on proteinuria as an effect modifier.

DATA SOURCES: MEDLINE and the Cochrane Central Register of Controlled Trials (July 2001 through January 2011) were searched for reports from randomized, controlled trials with no language restriction.

STUDY SELECTION: Authors screened abstracts to identify reports from trials comparing blood pressure targets in adults with CKD that had more than 50 participants per group; at least 1-year follow-up; and outcomes of death, kidney failure, cardiovascular events, change in kidney function, number of antihypertensive agents, and adverse events.

DATA EXTRACTION: Reviewers extracted data on study design, methods, sample characteristics, interventions, comparators, outcomes, number of medications, and adverse events and rated study quality and quality of analyses for proteinuria subgroups.

DATA SYNTHESIS: Three trials with a total of 2272 participants were included. Overall, trials did not show that a blood pressure target of less than 125/75 to 130/80 mm Hg is more beneficial than a target of less than 140/90 mm Hg. Lower-quality evidence suggests that a low target may be beneficial in subgroups with proteinuria greater than 300 to 1000 mg/d. Participants in the low target groups needed more antihypertensive medications and had a slightly higher rate of adverse events.

LIMITATIONS: No study included patients with diabetes. Trial duration may have been too short to detect differences in clinically important outcomes, such as death and kidney failure. Ascertainment and reporting of adverse events was not uniform.

CONCLUSION: Available evidence is inconclusive but does not prove that a blood pressure target of less than 130/80 mm Hg improves clinical outcomes more than a target of less than 140/90 mm Hg in adults with CKD. Whether a lower target benefits patients with proteinuria greater than 300 to 1000 mg/d requires further study.

We recently showed an association between strict BP control and lower mortality risk during two decades of follow-up of prior participants in the Modification of Diet in Renal Disease (MDRD) trial. Here, we determined the risk of ESRD and mortality during extended follow-up of the African American Study of Kidney Disease and Hypertension (AASK) trial. We linked 1067 former AASK participants with CKD previously randomized to strict or usual BP control (mean arterial pressure≤92 mmHg or 102-107 mmHg, respectively) to the US Renal Data System and Social Security Death Index; 397 patients had ESRD and 475 deaths occurred during a median follow-up of 14.4 years from 1995 to 2012. Compared with the usual BP arm, the strict BP arm had unadjusted and adjusted relative risks of ESRD of 0.92 (95% confidence interval [95% CI], 0.75 to 1.12) and 0.95 (95% CI, 0.78 to 1.16; P=0.64), respectively, and unadjusted and adjusted relative risks of death of 0.92 (95% CI, 0.77 to 1.10) and 0.81 (95% CI, 0.68 to 0.98; P=0.03), respectively. In meta-analyses of individual-level data from the MDRD and the AASK trials, unadjusted relative risk of ESRD was 0.88 (95% CI, 0.78 to 1.00) and unadjusted relative risk of death was 0.87 (95% CI, 0.76 to 0.99) for strict versus usual BP arms. Our findings suggest that, during long-term follow-up, strict BP control does not delay the onset of ESRD but may reduce the relative risk of death in CKD.

Importance: The optimal blood pressure (BP) target remains debated in nondiabetic patients with chronic kidney disease (CKD).

Objective: To compare intensive BP control (<130/80 mm Hg) with standard BP control (<140/90 mm Hg) on major renal outcomes in patients with CKD without diabetes.

Data Sources: Searches of PubMed, MEDLINE, Embase, and Cochrane Library for publications up to March 24, 2016.

Study Selection: Randomized clinical trials that compared an intensive vs a standard BP target in nondiabetic adults with CKD, reporting changes in glomerular filtration rate (GFR), doubling of serum creatinine level, 50% reduction in GFR, end-stagerenal disease (ESRD), or all-cause mortality.

Data Extraction and Synthesis: Random-effects meta-analyses for pooling effect measures. Meta-regression and subgroup analyses for exploring heterogeneity.

Main Outcomes and Measures: Differences in annual rate of change in GFR were expressed as mean differences with 95% CIs. Differences in doubling of serum creatinine or 50% reduction in GFR, ESRD, composite renal outcome, and all-cause mortality were expressed as risk ratios (RRs) with 95% CIs.

Results: We identified 9 trials with 8127 patients and a median follow-up of 3.3 years. Compared with standard BP control, intensive BP control did not show a significant difference on the annual rate of change in GFR (mean difference, 0.07; 95% CI, -0.16 to 0.29 mL/min/1.73 m2/y), doubling of serum creatinine level or 50% reduction in GFR (RR, 0.99; 95% CI, 0.76-1.29), ESRD (RR, 0.96; 95% CI, 0.78-1.18), composite renal outcome (RR, 0.99; 95% CI, 0.81-1.21), or all-cause mortality (RR, 0.95; 95% CI, 0.66-1.37). Nonblacks and patients with higher levels of proteinuria showed a trend of lower risk of kidney disease progression with intensive BP control.

Conclusions and Relevance: Targeting BP below the current standard did not provide additional benefit for renal outcomes compared with standard treatment during a follow-up of 3.3 years in patients with CKD without diabetes. However, nonblack patients or those with higher levels of proteinuria might benefit from the intensiveBP-lowering treatments.