Pam Harrison

November 07, 2015

SAN DIEGO — In patients with moderate to advanced chronic kidney disease (CKD), elevated systolic blood pressure is associated with a rapid decline in renal function, regardless of the presence or absence of albuminuria, new research suggests.

"Current guidelines for the management of blood pressure in patients with CKD recommend higher targets for patients without albuminuria than for those with albuminuria," said Natalie Staplin, PhD, from the Clinical Trial Service Unit and Epidemiological Studies Unit at Oxford University in the United Kingdom.

"Our findings suggest that using levels of albuminuria to decide on blood pressure targets in CKD may not be appropriate," she explained. However, she acknowledged that the results need to be confirmed in a large trial comparing intensive and standard blood pressure lowering.

Dr Staplin presented the results here at Kidney Week 2015: American Society of Nephrology Annual Meeting.

The study involved data from patients with CKD enrolled in the Study of Heart and Renal Protection (SHARP) trial. That trial established that the risk for myocardial infarction or stroke in patients with CKD was decreased when a statin-based regimen was used to lower levels of low-density lipoprotein cholesterol.

In their analysis, Dr Staplin and colleagues examined the association between systolic blood pressure and estimated glomerular filtration rate (eGFR) in patients with different levels of albuminuria in the urine.

At baseline, 20% of the 6000 patients had an eGFR below 15 mL/minute per 1.73 m2, 40% had an eGFR of 15 to 30 mL/minute per 1.73 m2, and 40% had an eGFR of 30 to 60 mL/minute per 1.73 m2.

"In our analysis, we used exposure of the long-term average systolic blood pressure so as not to underestimate the effects of systolic blood pressure on progression to end-stage renal disease," Dr Staplin reported.

Before adjustment for the presence of albuminuria, there was a 32% increase in the risk for end-stage renal disease with every 10 mm Hg increase in systolic blood pressure (hazard ratio [HR], 1.32; 95% confidence interval [CI], 1.23 - 1.41).

After adjustment for the presence of albuminuria, that risk decreased to 10%, although it remained significant (HR, 1.1; 95% CI, 1.03 - 1.18).

"For patients with high levels of albuminuria, each 20 mm Hg increase in systolic blood pressure was associated with a mean greater decline in eGFR of 0.7 mL/min per 1.73 m2 per year," Dr Staplin told Medscape Medical News.

In patients with low levels of albuminuria, and in those with no detectable albuminuria, the annual decline in eGFR was similar, at 0.6 mL/minute per 1.73 m2.

 
The SHARP study showed us very important data because, in fact, blood pressure is really the only thing we can control in patients with CKD to slow kidney disease progression. Dr Milos Budisavjevic
 

It is difficult to determine whether high blood pressure is the cause of renal disease progression, or whether progression of renal disease makes it more difficult to control blood pressure.

However, the SHARP data unequivocally showed that better blood pressure control can slow down the deterioration in eGFR in the absence and in the presence of albuminuria, said session cochair Milos Budisavjevic, MD, from Dialysis Clinic Inc in Charleston, South Carolina.

"I think the SHARP study showed us very important data because, in fact, blood pressure is really the only thing we can control in patients with CKD to slow kidney disease progression," he told Medscape Medical News.

"It's the only thing that works," he added. "This trial has provided us with good evidence that we can slow progression of kidney disease by optimally controlling systolic blood pressure, and that good blood pressure control works independently of albuminuria."

The study was supported by a grant from Merck/Schering-Plough Pharmaceuticals.

Kidney Week 2015: American Society of Nephrology Annual Meeting: Abstract TH-OR020. Presented November 5, 2015.

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