Larger Blood Pressure Declines Linked with Kidney Harm in SPRINT Trial

Greater reductions of mean arterial pressure were linked to reduced kidney function, according to an analysis of data from the SPRINT trial presented at Kidney Week.

The SPRINT trial demonstrated that tight blood pressure control—with a systolic target of less than 120 mm Hg—reduced the risk of death among nondiabetic patients at high risk of a cardiovascular event. But that tight control was associated with reduced kidney function.

To better understand the kidney-associated effects of tight blood pressure control, Rita Magriço, MD, of the Hospital Garcia de Orta in Portugal, and her colleagues took a second look at the SPRINT data. In their analysis, they grouped 1138 patients who received intensive blood pressure control based on whether their mean arterial pressure dropped by less than 20 mm Hg; between 20 and 39 mm Hg; or 40 or more mm Hg. They found that the roughly 10% of patients who achieved a 40 mm Hg or more drop in mean arterial pressure had a substantially elevated risk of chronic kidney disease (CKD) incidence compared with those whose pressure dropped between 20 and 39 mm Hg (HR 6.35 [95% CI, 2.82-14.29] vs. 2.14 [95% CI, 1.25-3.66]).

Based on their analysis, 43.5 patients would need to achieve a 20 mm Hg or less reduction for one to experience reduced death risk and one patient would experience CKD for every 65.4 treated. For those who reach a moderate target of a 20 to 39 mm Hg reduction, 41.7 would need to be treated and one would experience CKD for every 35.1 treated. By contrast, 95.2 patients would have to achieve a reduction of 40 mm Hg or more for one to benefit, while one patient would experience CKD for every 15.9 patients treated.

“The fact that in our analysis the benefit-risk relationship became less favorable with greater mean blood pressure reductions may be important for patients and physicians as they aim for the lowest cardiovascular risk with the lowest probability of side effects,” Magriço said. “If this association is confirmed by prospective studies, future recommendations for hypertension treatment in this population should consider personalized targets rather than a fixed cutoff for every patient.”

Lawrence Appel, MD, a professor at Johns Hopkins Bloomberg School of Public Health, cautioned that subgroup analyses of studies should be interpreted with caution as they are prone to false positives and false negatives.

“Be cautious, a subgroup analysis confined to small numbers of individuals can be misleading,” he said.

He noted that a recent meta-analysis of 30 randomized clinical trials found a 14% reduction in all cause mortality among CKD patients who received tight blood pressure control (Malhotra R, et al. JAMA Intern Med 2017; 177:1498–1505).

Based on the results to date, he does not think physicians should avoid tight blood pressure control unless they have a compelling clinical reason. He said more study is needed on reaching a blood pressure target between 120 and 140 mm Hg for patients with diabetes.

In the meantime, he suggested that patients most likely to benefit from preventive interventions, like tight blood pressure control, are likely those in the earlier stages of disease.

“Most of the action in terms of prevention is in people with stage 3 kidney disease,” Appel said. “That’s where you have the greatest opportunity for prevention. In the more advanced stages, it is going to be hard.”

“SPRINT Trial: Intensive Hypertension Treatment and Chronic Kidney Disease Incidence” (Abstract 2771812)

December 2017 (Vol. 9, Number 12)