Studies have shown that treating high blood pressure (BP) is one of the most important strategies to slowing the progression from chronic kidney disease (CKD) to end-stage renal disease (ESRD). Currently, a BP goal of less than 130/80 mm Hg is recommended for patients with CKD, a target lower than the goal recommended for people without CKD (less than 140/90 mm Hg). Despite the dissemination of clinical guidelines, meeting BP targets in people with CKD may be difficult in clinical practice.
“The most recent evidence supporting the use of lower BP targets in people with CKD has been conflicting,” explains Carmen A. Peralta, MD, MAS. “The association of BP levels and ESRD risk in a large, national, community-based setting of persons with established CKD has not been well studied. In addition, some recent reports have found that higher pulse pressure and lower diastolic BP (DBP) may lead to adverse cardiovascular outcomes. This can make it especially challenging for clinicians to control BP aggressively in patients with CKD.”
Associations Between BP and ESRD
Few studies have investigated the association of each BP component with ESRD risk. In Archives of Internal Medicine, Dr. Peralta and colleagues had a study published that investigated the independent association of systolic BP (SBP) and DBP with ESRD risk in patients with CKD who participated in the Kidney Early Evaluation Program (KEEP), a nationwide kidney health screening program offered by the National Kidney Foundation. More than 16,000 patients in KEEP were studied in the analysis, all of whom had at least stage III CKD.
“In the past, questions have been raised about the established BP targets for preventing ESRD because they’ve been studied mostly in randomized control trials, where participants tend to be healthier than the general population,” says Dr. Peralta. “The KEEP cohort gave us the opportunity to look at a community-based sample of regular Americans who have CKD.”
The results confirm that higher BP levels are associated with higher risk to develop ESRD. Most strikingly—despite dissemination of guidelines—the study found that more than one-third of patients with CKD had BPs of 150/90 mm Hg or higher, mostly due to isolated high SBP (Table 1). “The prevalence of uncontrolled hypertension was very high among people with CKD,” Dr. Peralta adds. “This was largely explained by isolated systolic hypertension.” Higher SBP was associated with higher ESRD risk, and this risk appeared to start at 140 mm Hg rather than at 130 mm Hg (the current target SBP for CKD). Furthermore, higher pulse pressure was associated with higher ESRD risk. People with SBPs of 150 mm Hg or higher and DBPs of less than 90 mm Hg were more likely to be older, non-Hispanic black, and have diabetes and albuminuria (Table 2).
Implications of Blood Pressure on CKD
A better understanding of the association of BP and ESRD risk among persons with CKD might help physicians provide better care for their patients with CKD, says Dr. Peralta. “The issue is daunting when more than one-third of persons with CKD are walking around with BPs higher than 150 mm Hg. Our study suggests that trying to get BP to less than 140 mm Hg may be beneficial in reducing ESRD risk.” Randomized trials have shown that lower goals (less than 130/80 mm Hg) reduce ESRD risk for persons with proteinuria, notes Dr. Peralta. “However, this lower goal can be especially hard for patients to achieve in clinical practice. Clinicians should focus more on patients with the highest and most uncontrolled BPs rather than be compelled to reach a goal of 130/80 mm Hg in everyone with CKD. More attainable BP goals may ease some of the challenges faced by physicians.” BP goal revisions might also enable physicians to prescribe fewer BP medications and focus more on other aspects of care. Greater efforts on patient education regarding BP control may also be of benefit.
More Research on Lowering Systolic BP
Educational strategies on BP control should focus on lowering SBP. More research is necessary to identify agents that lower arterial stiffness, Dr. Peralta says. “Our study had relatively few people with high degrees of proteinuria, and these individuals may benefit from even lower targets. Ideally, we should be working toward increasing our knowledge and understanding of the long-term associations of BP and ESRD risk as well as associations between BP components and risk for mortality or cardiovascular events. As these data emerge in subsequent studies, we’ll hopefully get a better picture of how we can optimize the management of BP in patients with CKD.”