Relationship Between Short‐Term Blood Pressure Variability and Subclinical Renal Damage in Essential Hypertensive Patients

Abstract

The authors aimed to analyze the relationship between subclinical renal damage, defined as the presence of microalbuminuria or an estimated glomerular filtration rate (eGFR) between 30 mL/min/1.73 m 2 and 60 mL/min/ 1.73 m 2 and short-term blood pressure (BP) variability, assessed as average real variability (ARV), weighted standard deviation (SD) of 24-hour BP, and SD of daytime and nighttime BP. A total of 328 hypertensive patients underwent 24-hour ambulatory BP monitoring, 24-hour albumin excretion rate determination, and eGFR calculation using the Chronic Kidney Disease Epidemiology Collaboration equation. ARV of 24-hour systolic BP (SBP) was significantly higher in patients with subclinical renal damage (P=.001). This association held (P=.04) after adjustment for potential confounders. In patients with microalbuminuria, ARV of 24-hour SBP, weighted SD of 24-hour SBP, and SD of daytime SBP were also independently and inversely related to eGFR. These results seem to suggest that in essential hypertension, short-term BP variability is independently associated with early renal abnormalities. J Clin Hypertens (Greenwich). 2015;17:473-480. ª 2015 Wiley Periodicals, Inc.Since the pioneering observations of Stephen Hales during the 18th century it has been recognized that blood pressure (BP) is not a constant parameter; rather, it shows marked spontaneous oscillations over shortterm (minutes to hours) and long-term (days to months) periods. Far from being a "background noise" that hindered assessment of "true BP," short-term BP variability (BPV) seems to be relevant to the pathophysiology of target organ damage and to the incidence of clinical events, as suggested by studies performed in humans by invasive continuous 24-hour BP measurements 1,2 and as clearly shown by investigations conducted in sinoaortic-denervated rats.3-6 Although the precise quantification of short-term BPV requires beatto-beat BP recording, 7 its assessment is also possible, even if less accurately, through the use of intermittent noninvasive 24-hour ambulatory BP monitoring (ABPM). However, studies in which short-term BPV was estimated by ABPM yielded conflicting results. 8-32Short-term BP variability has been usually estimated by 24-hour, daytime, or nighttime standard deviation (SD) of average BP. However, the limitations of the SD as a measure of short-term BPV have stimulated the search of more refined BPV estimates. 6,7,10,13,20,21 One of these is the average real variability (ARV) of 24-hour BP, ie, the average of the absolute differences of consecutive measurements. 20 This statistical parameter is sensitive to the individual BP measurement order and less sensitive to low sampling frequency of ABPM. 21Some studies suggest that ARV better predicts cardiovascular (CV) risk in comparison to the traditional SD. 20,22,23 Another new index of short-term BPV is the "weighted" SD of the 24-hour mean value, ie, the average SD of daytime and nighttime BP, each weighted for the duration of the day and night periods, respectively. This in order ...

Relationship Between Short-Term Blood Pressure Variability and Incidence of Acute Kidney Injury in Critically Ill Patients

“…The 24-h rate of SBP variation was shown to be a strong predictor of impaired renal function (OR per 0.1 mmHg/min increase, 1.49 [1.18–1.88]; p=0.001) [20]. Similar results were reported when linking other parameters of short-term BP variability (ARV of 24-hours SBP, weighted SD of 24-hours SBP) with eGFR in patients with microalbuminuria [7]. To the best of our knowledge, all the studies on BP variability and renal function were conducted in hypertensive patients; and data of critically ill patients, whose renal function was often impaired, was scarce.…”

“…An association between increased short-term BP variability and subclinical renal damage, which includes the presence of microalbuminuria or decrease of estimated glomerular filtration rate (eGFR), has been observed in essential hypertensive patients [7]. Kidney hypoxia or ischemia-reperfusion injury is thought to occur during the course of BP fluctuations,[8] which could occasionally develop into acute kidney injury (AKI), particularly in critically ill patients.…”

Long‐Term Visit‐to‐Visit Blood Pressure Variability and Renal Function Decline in Patients With Hypertension Over 15 Years

“…These studies have a shorter duration of follow‐up (3–4 years duration), which may not be able to show the effect of BPV on renal function decline. Other studies that examined short‐term 24‐hour BPV also showed that BPV was associated with decline in renal function, suggesting that both short‐ and long‐term BPV are important in determining the progression of kidney function deterioration in patients with hypertension …”

The Association Between Obesity and Visit-to-Visit Variability in Systolic Blood Pressure: A Prospective Study

“…The additional important factor is how obesity parameters variability during the long period (several years) influences the BPV, because prolonged obesity leads to development of uncontrolled blood pressures and cardiovascular complications (8,32,33).…”