Increased Blood Pressure Variability Prior to Chronic Kidney Disease Exacerbates Renal Dysfunction in Rats

Short-term blood pressure variability as a potential therapeutic target for kidney disease

Short-term blood pressure variability (BPV) measured with ambulatory blood pressure (BP) monitoring has been demonstrated to be significant in predicting various clinical outcomes. Short-term BPV is distinguished from long-term BPV based on the time interval in which BP fluctuations are measured. Increased short-term BPV has been linked to detrimental effects on the microvascular structure and contributes to subclinical organ damage in the heart, blood vessels, and kidneys, regardless of the average 24-h BP levels. Short-term BPV can be defined by various measures, including calculated metrics (standard deviation, coefficient of variation, average real variability, weighted standard deviation, variability independent of the mean) or dipping patterns. Nevertheless, the additional role of short-term BPV beyond the predictive value of average 24-h BPs or established risk factors for cardiovascular disease and kidney disease remains unclear. In particular, longitudinal studies that evaluate the association between short-term BPV and kidney function impairment are limited and no conclusive data exist regarding which short-term BPV indicators most accurately reflect the prognosis of kidney disease. The issue of how to treat BPV in clinical practice is another concern that is frequently raised. This paper presents a review of the evidence for the prognostic role of short-term BPV in kidney outcomes. Additionally, this review discusses the remaining concerns about short-term BPV that need to be further investigated as an independent risk modifier.

Hypertension in chronic kidney disease: What lies behind the scene

Hypertension is a frequent condition encountered during kidney disease development and a leading cause in its progression. Hallmark factors contributing to hypertension constitute a complexity of events that progress chronic kidney disease (CKD) into end-stage renal disease (ESRD). Multiple crosstalk mechanisms are involved in sustaining the inevitable high blood pressure (BP) state in CKD, and these play an important role in the pathogenesis of increased cardiovascular (CV) events associated with CKD. The present review discusses relevant contributory mechanisms underpinning the promotion of hypertension and their consequent eventuation to renal damage and CV disease. In particular, salt and volume expansion, sympathetic nervous system (SNS) hyperactivity, upregulated renin–angiotensin–aldosterone system (RAAS), oxidative stress, vascular remodeling, endothelial dysfunction, and a range of mediators and signaling molecules which are thought to play a role in this concert of events are emphasized. As the control of high BP via therapeutic interventions can represent the key strategy to not only reduce BP but also the CV burden in kidney disease, evidence for major strategic pathways that can alleviate the progression of hypertensive kidney disease are highlighted. This review provides a particular focus on the impact of RAAS antagonists, renal nerve denervation, baroreflex stimulation, and other modalities affecting BP in the context of CKD, to provide interesting perspectives on the management of hypertensive nephropathy and associated CV comorbidities.

Day-to-Day Blood Pressure Variability and Risk of Incident Chronic Kidney Disease in a General Japanese Population

Background Several longitudinal studies have reported that higher visit-to-visit blood pressure variability is associated with greater risk for developing chronic kidney disease. However, no population-based studies have investigated the association between day-to-day home blood pressure variability and incident chronic kidney disease. Methods and Results A total of 2342 Japanese community-dwelling residents aged ≥40 years without chronic kidney disease at baseline were followed up by annual health examinations for 10 years. Home blood pressure was measured 3 times every morning for 28 days. Day-to-day coefficients of variation of home systolic blood pressure levels were categorized into quintiles. Chronic kidney disease was defined as an estimated glomerular filtration rate <60 mL/min per 1.73 m² or the presence of proteinuria. The hazard ratios for developing chronic kidney disease were estimated with a Cox proportional hazards model. During the follow-up period, 772 participants developed chronic kidney disease. Increased coefficients of variation of home systolic blood pressure were associated significantly with higher risk of chronic kidney disease after adjusting for confounders (P for trend <0.001): Individuals in the highest quintile of coefficients of variation had a 1.50-fold (95% CI, 1.17-1.94) greater risk of developing chronic kidney disease than those in the lowest quintile. The combination of higher coefficients of variation and higher mean value of home systolic blood pressure was associated with the multivariable-adjusted risk of developing chronic kidney disease. Conclusions These findings suggest that increased day-to-day blood pressure variability is a significant risk factor for developing chronic kidney disease in a general Japanese population.

Visit-to-visit variability in blood pressure and the development of chronic kidney disease in treated general hypertensive patients

BACKGROUND

Data on the association between visit-to-visit variability (VVV) in blood pressure (BP) and the risk of chronic kidney disease (CKD) in general treated hypertensive patients were limited. We aimed to evaluate the relation of VVV in BP with the development of CKD, and examine any possible effect modifiers in hypertensive patients without prior cardiovascular diseases (CVDs) or CKD.

METHODS

This is a post hoc analysis of the Renal Sub-study of the China Stroke Primary Prevention Trial (CSPPT). A total of 10 051 hypertensives without CVD and CKD and with at least six visits of BP measurements from randomization to the 24-month visit were included. The main VVV in BP was expressed as standard deviation (SD). The primary outcome was the development of CKD, defined as a decrease in estimated glomerular filtration rate ≥30% and to a level of <60 mL/min/1.73 m2, or end-stage renal disease.

RESULTS

The median treatment duration was 4.4 years. After multivariable adjustment, including baseline systolic blood pressure (SBP) and mean SBP during the first 2-year treatment period, there was a significantly positive relationship of SD of SBP with the risk of CKD development (per SD increment; odds ratio, 1.27; 95% confidence interval: 1.10-1.46). The results were similar for coefficient of variation (CV) of SBP. Results across various subgroups, including age, sex, SBP at baseline, treatment compliance, concomitant antihypertensive medications and mean SBP during the first 24-month treatment period, were consistent.

CONCLUSIONS

SBP variability, irrespective of mean BP level, was significantly associated with the development of CKD in general treated hypertensive patients.

Visit-to-visit blood pressure variability and risk of chronic kidney disease: A systematic review and meta-analyses

Objective

Previous studies have shown that visit-to-visit blood pressure variability (BPV) is associated with chronic kidney disease (CKD). However, the results have not been consistent among studies. This systematic review and meta-analysis was conducted to comprehensively assess the association between visit-to-visit BPV and the risk of CKD.

Methods

Medline, Embase, and the Cochrane Library were searched from the date of inception through 1 August 2019 using the terms “blood pressure variability,” “chronic kidney disease,” “nephropathy,” and other comparable terms. The primary outcome was the development of CKD. Two reviewers extracted the data independently. Meta-analysis was performed using a random effects model.

Results

Fourteen studies were included in the systematic review and meta-analysis. The risk of CKD was significantly greater in patients with high baseline systolic blood pressure variability (SBPV) than in patients with low baseline SBPV: the standard deviation (SD) showed relative risk (RR) of 1.69 and 95% CI of 1.38–2.08, the coefficient of variation (CV) showed RR of 1.23 and 95% CI of 1.12–1.36, and variance independent of mean (VIM) showed RR of 1.40 and 95% CI of 1.15–1.71. RRs for each unit increase in visit-to-visit SBPV and risk of CKD were 1.05 (95% CI: 1.03–1.07) for SD, 1.06 (95% CI: 1.03–1.09) for CV, and 1.1 (95% CI: 0.96–1.25) for VIM. Diastolic BPV was similarly predictive of CKD based on SD and CV.

Conclusions

Increased visit-to-visit BPV might be an independent risk factor for CKD. However, significant heterogeneity was present; thus, future prospective studies are needed to confirm our findings. Our results indicate that treatment of hypertension should control blood pressure levels and prevent abnormal fluctuations in blood pressure to reduce the risk of CKD.

Short-term blood pressure variability in nondialysis chronic kidney disease patients: correlates and prognostic role on the progression of renal disease

OBJECTIVE

In chronic kidney disease (CKD), few cross-sectional studies evidenced an association between short-term BP variability (BPV) derived from ambulatory blood pressure (ABP) monitoring and renal damage. However, no study has evaluated the association of short-term BPV with the risk of CKD progression.

METHODS

We performed a cohort study to assess the correlates and the predictive value for incident renal outcomes of short-term BPV in hypertensive patients with CKD stage G1-5. As measures of short-term BPV, we considered the weighted SD (W-SD), and the coefficient of variation of SBP (CV-24-h SBP). Primary outcome was a composite endpoint of ESRD (chronic dialysis or transplantation) or GFR decline of at least 50%.

RESULTS

We included 465 patients (63.5 ± 14.2 years; 54.7% men; eGFR: 44 ± 22 ml/min per 1.73 m; proteinuria: 0.2 [0.1-0.9] g/day); W-SD, CV-24-h SBP and 24 h SBP were 12.5 ± 3.3 mmHg, 11.1 ± 2.8% and 127 ± 16 mmHg, respectively. W-SD was independently associated with older age, history of cardiovascular disease, diagnosis of diabetic, hypertensive and polycystic nephropathy, and higher 24 h SBP whereas no association with eGFR and proteinuria was found. During follow-up (median, 6.4 years), 130 patients reached the renal outcome (107 ESRD and 23 GFR decline of ≥50%). Higher 24 h, daytime and night-time SBP robustly predicted the composite renal endpoint [1.18 (1.10-1.25) for 5 mmHg], whereas BPV as measured by the W-SD did not either when expressed as a continuous variable [hazard ratio 0.97 (95% CI 0.91-1.04)] or when categorized into tertiles [1.16 (0.70-1.92) and 0.95 (0.54-1.68) in II and III tertiles, respectively]. Similar findings were found with CV-24-h SBP.

CONCLUSION

In CKD patients, short-term BPV is strongly associated with 24 h, night-time and daytime BP but is independent from the eGFR and proteinuria and does not predict CKD progression.