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

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Introduction: 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.

Methods: 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.

Results: 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.

Conclusions: 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.