# Clinical Significance of Mean and Day-to-Day Variability of Home Blood Pressure in Chronic Kidney Disease: A Retrospective Cohort Study

## TL;DR

This study shows that both high average blood pressure and its daily fluctuations may worsen kidney disease progression.

## Contribution

The novel finding is that blood pressure variability interacts with mean blood pressure to worsen chronic kidney disease outcomes.

## Key findings

- Higher mean systolic blood pressure was linked to faster kidney function decline.
- Blood pressure variability alone did not predict outcomes but interacted with mean BP to worsen kidney disease.
- Stabilizing blood pressure may be important alongside lowering it in CKD patients.

## Abstract

Hypertension is a key risk factor for chronic kidney disease (CKD) progression. While mean blood pressure (BP) is well known to predict kidney outcomes, the role of BP variability (BPV)―especially day-to-day variability measured at home―in CKD remains unclear.

In this retrospective cohort study of 150 patients with CKD, home systolic BP (SBP) was measured daily for up to 28 days. Mean SBP and day-to-day BPV (standard deviation of daily SBP) were calculated. Associations with the annual estimated glomerular filtration rate (eGFR) slope and a composite kidney endpoint (≥40% eGFR decline, kidney failure, or kidney-related death) were analyzed using linear mixed-effects models and Cox regression. The interaction between mean SBP and BPV on kidney outcomes was also evaluated.

The study population consisted of 150 patients (mean age, 66.1 years; 52% male) with a mean baseline eGFR of 43.2 mL/min/1.73 m2. Higher mean SBP was significantly associated with a steeper eGFR decline and increased risk of the composite kidney endpoint. In contrast, BPV was not independently associated with kidney outcomes. However, a significant interaction was observed, indicating that the detrimental effect of elevated mean SBP on kidney progression was amplified in patients with higher BPV.

Mean home SBP was significantly associated with CKD progression. Although BPV alone was not independently related to outcomes, its interaction with mean SBP suggests that BP instability may exacerbate hypertension-related kidney damage. These findings highlight the clinical importance of both lowering and stabilizing BP in CKD management.