Blood Pressure Variability and Chronic Kidney Disease

Blood pressure (BP) variability (BPV) is an emerging mediator of clinical outcomes. The association between long-term BPV and the risk of incident chronic kidney disease (CKD) has been repeatedly reported in the general population. A recent study suggests that low urine potassium excretion is independently associated with high BPV in patients with pre-dialysis CKD. The study findings were published in the journal Nutrients on December 13, 2021.

Dietary potassium intake is a dilemma in patients with CKD. Studies have shown potassium-rich diets reduce CV events and all-cause mortality in the general population. However, whether low dietary potassium negatively affects CV outcomes in CKD patients remains unclear. Therefore, Dr. Soo Wan Kim and his team conducted a study to evaluate the association of urine potassium excretion, a surrogate for dietary potassium intake, with BPV and cardiovascular (CV) outcomes in patients with pre-dialysis CKD.

The Korean Cohort Study for Outcomes in Patients with Chronic Kidney Disease (KNOW-CKD) is a nationwide prospective cohort study involving 9 tertiary-care general hospitals in Korea. They included a total of 1860 patients from a cohort of pre-dialysis CKD (KNOW-CKD) and divided them into quartiles by spot urine potassium-to-creatinine ratio, where the 1st and 4th quartiles were defined as low and high, respectively. The major outcomes assessed were incidence of extended major cardiovascular events (eMACEs) and all-cause mortality.

Key Findings of the Study

• Upon multivariate linear regression analyses, they found an independent association of low urine potassium excretion with high BPV (adjusted β coefficient 1.163).
• Using Cox regression analyses, they found that, compared to high urine potassium excretion, low urine potassium excretion is associated with increased risk of CV events (adjusted hazard ratio 2.502) but not with all-cause mortality.

The authors concluded, "We report that low urine potassium excretion is independently associated with high BPV and is also significantly associated with increased risk of eMACE in patients with pre-dialysis CKD. Considering the potential CV benefit conferred by a high potassium diet, the restriction of dietary potassium intake should be individualized in patients with pre-dialysis CKD."

For Further Information

DOI: https://doi.org/10.3390/nu13124443