Best Target Blood Pressure for Patients with Chronic Kidney Disease?

Large study examines BP and specific causes of death

What is the best target blood pressure for patients with chronic kidney disease (CKD) remains a controversial topic.

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The 2010 ACCORD randomized controlled study found that managing patients’ blood pressure to less than 120/80 mm Hg could actually increase mortality among diabetics. On the other hand, the 2015 SPRINT randomized control study found fewer overall deaths and fewer deaths from cardiovascular disease in patients with pressure less than 120/80 mm Hg. This held true for patients older than 70 and for a modest number of patients with mild CKD. However, the SPRINT trial did not include diabetic patients or those who had prior strokes.

To help resolve this conflict, Cleveland Clinic researchers recently conducted an observational study of the associations between blood pressure and various causes of death in a CKD population.

“This is the first time that cause-specific death has been looked at in a observational study with large numbers — more than 45,000 patients and over 13,000 deaths,” says study co-author Joseph Nally Jr., MD, emeritus Director of the Center for Chronic Kidney Disease in Cleveland Clinic’s Glickman Urological & Kidney Institute. The study was published in July in Kidney International.

Association (adjusted) between systolic blood pressure and all-cause death in chronic kidney disease. (Figure copyrighted by and reprinted with permission from Kidney International.)

“What we found was a J-shaped curve,” Dr. Nally explains. “For individuals whose systolic blood pressure was greater than 150 mm Hg, there was an increase in all-cause and cardiovascular death. For those with SBP less than 120 mm Hg, there was also increased all-cause mortality and cardiovascular death.”

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Comorbidities and lower blood pressure

Dr. Nally and his colleagues used data from the Ohio Department of Health mortality files and classified deaths into three categories: cardiovascular, malignancy-related and noncardiovascular-/nonmalignancy-related.

Subjects (patients seen in the Cleveland Clinic health system from 2005 to 2013) had eGFR 15-59 ml/min/1.73 m2 with underlying hypertension and were prescribed at least one antihypertensive agent. Researchers identified 45,412 patients with this profile and found that over four years, 13,332 had died.

Data showed that patients with systolic blood pressures under 100, 100-109, 110-119, and over 150 (vs. 130-139 mm Hg) were associated with higher all-cause and cardiovascular mortality.

“Since we had a complete data set, we were able examine comorbidities,” Dr. Nally adds. “We found those with CKD plus heart failure, liver disease or diabetes, had an increased chance of death with pressures at 110 compared with people who had the same comorbidities and blood pressure at 130.”

New randomized controlled trial needed

It’s unclear why blood pressure below 120 mm Hg may be dangerous for people with CKD and significant comorbidities.

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“For today’s clinician, Dr. Navaneethan* and I feel that our findings offer a note of caution regarding targeting systolic blood pressure less than 120 mm Hg for higher-risk CKD patients with diabetes and/or heart failure,” Dr. Nally says.

“Observational studies like ours identify associations, but not causation. We need further randomized clinical trials similar to SPRINT that include diabetic patients as well as people with cardiac disease or prior strokes to determine whether lower blood pressure is in fact better for higher-risk populations.”

*Co-author Sankar D. Navaneethan, MBBS, MPH, now at Baylor College of Medicine, Houston.