Predictors of daytime blood pressure, nighttime blood pressure, and nocturnal dipping in patients with chronic kidney disease

Increasing attention has recently been paid to discrepancies between office and ambulatory blood pressure (BP) control in patients with chronic kidney disease (CKD), but information on mechanisms underlying circadian BP variations in CKD remains scarce. We described circadian BP patterns and their predictors in patients with CKD stages 1 to 5 referred for kidney function testing in a French tertiary hospital: 1122 ambulatory BP measurements from 635 participants. Factors associated with daytime and nighttime systolic BP (SBP) as well as with nocturnal SBP dipping (ratio of average nighttime to daytime SBP) were analyzed with linear mixed regression models. Participants (mean age 55 ± 16 years; 36% female, mean GFR 51 ± 22 mL/min/1.73m2) had a mean daytime and nighttime SBP of 130 ± 17 and 118 ± 18 mm Hg, respectively. The prevalence of impaired dipping (nighttime over daytime SBP ratio ≥ 0.9) increased from 32% in CKD stage 1 to 68% in CKD stages 4-5. After multivariable adjustment, measured GFR, diabetes, and sub-Saharan African origin were more strongly associated with nighttime than with daytime SBP, which led to significant associations with altered nocturnal BP dipping. For a 1 SD decrease in measured GFR, nighttime BP was 2.87 mmHg (95%CI, 1.44-4.30) higher and nocturnal SBP dipping ratio was 1.55% higher (95%CI, 0.85-2.26%). In conclusion, the prevalence of impaired nocturnal BP dipping increases substantially across the spectrum of CKD. Along with sub-Saharan African origin and diabetes, lower measured GFR was a robust and specific predictor of higher nighttime BP and blunted nocturnal BP decline.

Prevalence and factors associated with masked hypertension in chronic kidney disease

OBJECTIVES

Optimal blood pressure (BP) control is key to prevent cardiovascular complications in patients with chronic kidney disease (CKD). We described the prevalence and factors associated with masked hypertension in CKD.

METHODS

We analyzed 1113 ambulatory 24-h BP monitoring (ABPM) records of 632 patients referred for kidney function evaluation. Masked hypertension was defined as office BP less than 140/90 mmHg but daytime BP at least 135/85 mmHg or nighttime BP at least 120/70 mmHg. Factors associated with masked hypertension were assessed with mixed logistic regression models.

RESULTS

At inclusion, 424 patients (67%) had controlled office BP, of whom 56% had masked hypertension. In multivariable analysis conducted in all visits with controlled office BP ( n  = 782), masked hypertension was positively associated with male sex [adjusted OR (95% confidence interval) 1.91 (1.16-3.27)], sub-Saharan African origin [2.51 (1.32-4.63)], BMI [1.11 (1.01-1.17) per 1 kg/m 2 ], and albuminuria [1.29 [1.12 - 1.47] per 1 log unit), and was negatively associated with plasma potassium (0.42 [0.29 - 0.71] per 1 mmol/L) and 24-h urinary potassium excretion (0.91 [0.82 - 0.99] per 10 mmol/24 h) as well as the use of renin-angiotensin-aldosterone (RAAS) blockers (0.56 [0.31 - 0.97]) and diuretics (0.41 [0.27 - 0.72]).

CONCLUSION

Our findings support the routine use of ABPM in CKD, as more than half of the patients with controlled office BP had masked hypertension. Weight control, higher potassium intake (with caution in advanced CKD), correction of hypokalemia, and larger use of diuretics and RAAS blockers could be potential levers for better out-of-office BP control.

Very low-calorie ketogenic diet (VLCKD): an antihypertensive nutritional approach

BACKGROUND

Obesity is accompanied by hormonal, inflammatory and endothelial alterations. These alterations induce a stimulation of several other mechanisms that contribute to the hypertensive state and to increase the cardiovascular morbidity. This pilot, open - label, single- center, prospective clinical trial aimed to evaluate the effect of very low- calorie ketogenic diet (VLCKD) on blood pressure (BP) in women with of obesity and hypertension.

METHODS

A total of 137 women, who met the inclusion criteria and accepted to adhere to VLCKD, were consecutively enrolled. Assessment of anthropometric parameters (weight, height, and waist circumference), body composition (through bioelectrical impedance analysis), systolic (SBP) and diastolic blood pressure (DBP) and blood sample collection were carried out at baseline and after 45 days of the active phase of VLCKD.

RESULTS

After VLCKD all the women experienced a significant reduction in body weight and an overall improvement of body composition parameters. In addition, high sensitivity C reactive protein (hs- CRP) levels were significantly diminished (p < 0.001), while phase angle (PhA) increased by almost 9% (p < 0.001). Interestingly, both SBP and DBP were significantly improved (-12.89% and - 10.77%, respectively; p < 0.001). At baseline, SBP and DBP showed statistically significant correlations with body mass index (BMI), waist circumference, hs-CRP levels, PhA, total body water (TBW), extracellular water (ECW), Na / K ratio, and fat mass. Even after VLCKD, all correlations among SBP and DBP with the study variables were statistically significant, except for the association between DBP and Na / K ratio. Changes (%) in both SBP and DBP were associated with ∆BMI%, ∆PhA% and ∆hs- CRP levels (p < 0.001). In addition, only ∆SBP% was associated with ∆waist circumference (p = 0.017), ∆TBW (p = 0.017), and ∆fat mass (p < 0.001); while only ∆DBP% was associated with ∆ECW (p = 0.018), and ∆Na / K ratio (p = 0.048). After adjusting for ∆BMI, ∆WC, ∆PhA, ∆TBW, and ∆fat mass, the correlation between changes in ∆SBP and ∆hs -CRP levels remained statistically significant (p < 0.001). Similarly, the correlation between ∆DBP and ∆hs- CRP levels also remained statistically significant after adjustment for ∆BMI, ∆PhA, ∆Na / K ratio, and ∆ECW (p < 0.001). From multiple regression analysis ∆hs- CRP levels seemed to be the main predictor of changes of BP (p < 0.001).

CONCLUSION

VLCKD reduces BP in women with of obesity and hypertension in a safely manner.

Revisiting diuretic choice in chronic kidney disease

PURPOSE OF REVIEW

Existing guidelines offer little direction about the use of thiazide and loop diuretics in patients with chronic kidney disease (CKD). This review summarizes recent studies impacting indications and safety considerations for these agents in patients with CKD.

RECENT FINDINGS

Chlorthalidone reduces blood pressure compared to placebo in patients with advanced CKD, challenging the belief that thiazide diuretics lose efficacy at lower glomerular filtration rates (GFR). Existing studies show no clear impact of thiazide or loop diuretic use on kidney or cardiovascular outcomes in patients with CKD. Sodium-glucose co-transporter type 2 (SGLT2) inhibitors have diuretic effects, but concomitant use of a diuretic does not diminish the preventive benefits of these agents against acute kidney injury (AKI). Despite theoretical concerns, thiazide diuretics likely do not worsen circulating vasopressin levels or cyst progression in polycystic kidney disease and may be useful for alleviating polyuria from tolvaptan. Diuretics cause multiple adverse effects, including electrolyte abnormalities, hemodynamic-mediated decrease in estimated GFR, and AKI.

SUMMARY

Recent evidence supports expanded indications for diuretics in patients with kidney disease, including chlorthalidone for hypertension in advanced CKD. Monitoring electrolytes and estimated GFR is critical to ensure patient safety when prescribing these agents for patients with CKD.

Assessment of Hydration Status and Blood Pressure in a Tertiary Care Hospital at Al-Khobar

Background

High blood pressure is a major cardiovascular risk factor. It is a leading cause of increasing morbidity and mortality worldwide. One-third of the adult population worldwide suffers from hypertension. Salt intake, obesity, decreased physical activity, and smoking are well known to increase blood pressure. Fluid retention is the main contributing factor to primary hypertension and adversely affects the cardiovascular system. The emerging evidence suggests a relationship between blood pressure and hydration status. Our study aims to assess the correlation between hydration status and blood pressure. We aim to assess the hydration status in subjects with normal and high blood pressure and to investigate the association of hydration status with hemodynamic measurement.

Methodology

This cross-sectional and observational study included adult (>18 years) male and female subjects who agreed to participate. In total, 235 subjects were recruited by convenience sampling from (1) patients and caregivers attending geriatric and internal medicine clinics, and (2) visitors coming to King Fahad University Hospital at Al-Khobar. There were five patients on oral diuretics who were excluded from the study. Data were collected from September 2021 to March 2022. Hydration status was measured by a bioelectrical impedance analyzer (Bioscan 920, Maltron International Ltd. Rayleigh, UK). Hemodynamic measurements included heart rate per minute, systolic blood pressure, diastolic blood pressure, pulse pressure (the difference between systolic and diastolic blood pressure), and mean arterial pressure calculated as blood diastolic pressure plus one-third of pulse pressure. Statistical analyses were performed using SPSS statistics for windows, version 28.0 (IBM Corp., Armonk, NY, USA). Descriptive data were reported using means with standard deviations for numerical data and relative frequencies (percentage) for categorical data. P-values of less than 0.05 were considered statistically significant. Comparison between groups was done using a one-way analysis of variance test.

Results

Extracellular water percentage was higher in hypertensive (45.0 ± 2) than prehypertensive (43.5 ± 3) or normotensive (43.0 ± 2) (p = 0.001) subjects. In contrast, intracellular water percentage and total body water percentage were significantly negatively related to hypertension status.

Conclusions

Our results have shown a strong association between hypertension status and hydration parameters. In our study, hypertensive subjects tended to have lower total body water percentage and intracellular water percentage (bioimpedance value) than normotensive subjects. This might promote more research regarding the relationship between hypohydration and cardiovascular disease pathophysiology. This outcome should raise awareness about proper hydration as hypohydration can be a causative factor for hypertension.

Extracellular Fluid Volume Is an Independent Determinant of Uncontrolled and Resistant Hypertension in Chronic Kidney Disease: A NephroTest Cohort Study

Background

Hypertension is highly prevalent during chronic kidney disease (CKD) and, in turn, worsens CKD prognosis. We aimed to describe the determinants of uncontrolled and resistant hypertension during CKD.

Methods and Results

We analyzed baseline data from patients with CKD stage 1 to 5 (NephroTest cohort) who underwent thorough renal explorations, including measurements of glomerular filtration rate (clearance of ⁵¹Cr‐EDTA) and of extracellular water (volume of distribution of the tracer). Hypertension was defined as blood pressure (BP; average of 3 office measurements) ≥140/90 mm Hg or the use of antihypertensive drugs. In 2015 patients (mean age, 58.7±15.3 years; 67% men; mean glomerular filtration rate, 42±15 mL/min per 1.73 m²), prevalence of hypertension was 88%. Among hypertensive patients, 44% and 32% had uncontrolled (≥140/90 mm Hg) and resistant (uncontrolled BP despite 3 drugs, including a diuretic, or ≥4 drugs, including a diuretic, regardless of BP level) hypertension, respectively. In multivariable analysis, extracellular water, older age, higher albuminuria, diabetic nephropathy, and the absence of aldosterone blockers were independently associated with uncontrolled BP. Extracellular water, older age, lower glomerular filtration rate, higher albuminuria and body mass index, male sex, African origin, diabetes mellitus, and diabetic and glomerular nephropathies were associated with resistant hypertension.

Conclusions

In this large population of patients with CKD, a lower glomerular filtration rate, a higher body mass index, diabetic status, and African origin were associated with hypertension severity but not with BP control. Higher extracellular water, older age, and higher albuminuria were independent determinants of both resistant and uncontrolled hypertension during CKD. Our results advocate for the large use of diuretics in this population.

Association Between High and Very High Albuminuria and Nighttime Blood Pressure: Influence of Diabetes and Chronic Kidney Disease

OBJECTIVE

Nighttime blood pressure (BP) and albuminuria are two important and independent predictors of cardiovascular morbidity and mortality. Here, we examined the quantitative differences in nighttime systolic BP (SBP) across albuminuria levels in patients with and without diabetes and chronic kidney disease.

RESEARCH DESIGN AND METHODS

A total of 16,546 patients from the Spanish Ambulatory Blood Pressure Monitoring Registry cohort (mean age 59.6 years, 54.9% men) were analyzed. Patients were classified according to estimated glomerular filtration rate (eGFR), as ≥60 or <60 mL/min/1.73 m(2) (low eGFR), and urine albumin-to-creatinine ratio, as normoalbuminuria (<30 mg/g), high albuminuria (30-300 mg/g), or very high albuminuria (>300 mg/g). Office and 24-h BP were determined with standardized methods and conditions.

RESULTS

High albuminuria was associated with a statistically significant and clinically substantial higher nighttime SBP (6.8 mmHg higher than with normoalbuminuria, P < 0.001). This association was particularly striking at very high albuminuria among patients with diabetes and low eGFR (16.5 mmHg, P < 0.001). Generalized linear models showed that after full adjustment for demographic, lifestyles, and clinical characteristics, nighttime SBP was 4.8 mmHg higher in patients with high albuminuria than in those with normoalbuminuria (P < 0.001), and patients with very high albuminuria had a 6.1 mmHg greater nighttime SBP than those with high albuminuria (P < 0.001). These differences were 3.8 and 3.1 mmHg, respectively, among patients without diabetes, and 6.5 and 8 mmHg among patients with diabetes (P < 0.001).

CONCLUSIONS

Albuminuria in hypertensive patients is accompanied by quantitatively striking higher nighttime SBP, particularly in those with diabetes with very high albuminuria and low eGFR.

Diuretics and bioimpedance-measured fluid spaces in hypertensive patients

The authors examined the relationship between thiazide-type diuretics and fluid spaces in a cohort of hypertensive patients in a retrospective study of 60 stable hypertensive patients without renal abnormalities who underwent whole-body bioimpedance analysis. Overhydration was greater in the diuretic group, but only to a nonsignificant degree (5.9 vs. 2.9%; P=.21). The total body water did not differ in the two groups (41.8 L vs. 40.5 L; P=.64). Extracellular fluid volume (ECV) (19.7 L vs. 18.5 L; P=.35) and intracellular fluid volume (ICV) spaces (20.8 L vs. 21.3 L; P=.75) were also not significantly different in the two groups. The ratio of ICV:ECV, however, appeared different: 1.05 vs 1.15 (P=.017) and the effect was maintained in the linear regression-adjusted model (β coefficient: -0.143; P=.001). The diuretic-related distortion of ICV:ECV ratio indicates potential fluid redistribution in hypertensive patients, with ICV participating in the process.