Effects of Intensive Blood Pressure Lowering on Kidney Tubule Injury in CKD: A Longitudinal Subgroup Analysis in SPRINT

Tubular Biomarkers and Chronic Kidney Disease Progression in SPRINT Participants

BACKGROUND

Kidney tubular atrophy on biopsy is a strong predictor of chronic kidney disease (CKD) progression, but tubular health is poorly quantified by traditional measures including estimated glomerular filtration rate (eGFR) and albuminuria. We hypothesized that urinary biomarkers of impaired tubule function would be associated with faster eGFR declines in persons with CKD.

METHODS

We measured baseline urine concentrations of uromodulin, β2-microglobulin (β2m), and α1-microglobulin (α1m) among 2,428 participants of the Systolic Blood Pressure Intervention Trial with an eGFR <60 mL/min/1.73 m2. We used linear mixed models to evaluate biomarker associations with annualized relative change in eGFR, stratified by randomization arm.

RESULTS

At baseline, the mean age was 73 ± 9 years and eGFR was 46 ± 11 mL/min/1.73 m2. In the standard blood pressure treatment arm, each 2-fold higher urinary uromodulin was associated with slower % annual eGFR decline (0.34 [95% CI: 0.08, 0.60]), whereas higher urinary β2m was associated with faster % annual eGFR decline (-0.10 [95% CI: -0.18, -0.02]) in multivariable-adjusted models including baseline eGFR and albuminuria. Associations were weaker and did not reach statistical significance in the intensive blood pressure treatment arm for either uromodulin (0.11 [-0.13, 0.35], p value for interaction by treatment arm = 0.045) or β2m (-0.01 [-0.08, 0.08], p value for interaction = 0.001). Urinary α1m was not independently associated with eGFR decline in the standard (0.01 [-0.22, 0.23]) or intensive (0.03 [-0.20, 0.25]) arm.

CONCLUSIONS

Among trial participants with hypertension and CKD, baseline measures of tubular function were associated with subsequent declines in kidney function, although these associations were diminished by intensive blood pressure control.

Prevention of heart failure events with intensive versus standard blood pressure lowering across the spectrum of kidney function and albuminuria: a SPRINT substudy

AIMS

To determine whether a strategy of intensive blood pressure control reduces the risk of heart failure (HF) events consistently across the spectrum of kidney function and albuminuria.

METHODS AND RESULTS

SPRINT was a randomized clinical trial in which 9361 individuals ≥50 years, at high risk for or with cardiovascular disease, a systolic blood pressure of 130-180 mmHg, but without diabetes, were randomized to intensive (target <120 mmHg) vs. standard (target <140 mmHg) blood pressure control. We assessed whether estimated glomerular filtration rate (eGFR) and urine albumin-to-creatinine ratio (UACR) modified the effects of the blood pressure control strategy in reducing HF events (either hospitalization or emergency department visits) and the composite of HF events or cardiovascular death, using Cox proportional hazards regression and restricted cubic splines. Of the 9361 individuals included in SPRINT, eGFR and UACR were available for 9324 (99.6%) and 8913 (95.2%) subjects, respectively, including 2650 (28.4%) with eGFR <60 mL/min/1.73 m² and 248 (2.8%) with UACR >300 mg/g. During a median follow-up of 3.2 years (range 0-4.8 years), 160 (1.8%) participants had HF events and 233 (2.6%) had HF events or cardiovascular death. Risks of HF events or cardiovascular death increased from 0.42 (0.34-0.53) per 100 patient-years in patients with eGFR ≥60 mL/min/1.73 m² and UACR <30 mg/g to 4.55 (3.00-6.91) per 100 patient-years in patients with eGFR <60 mL/min/1.73 m² and UACR >300 mg/g. A similar gradient was observed for HF events alone. Both eGFR and UACR were independently, non-linearly associated with HF hospitalization and HF hospitalization or cardiovascular death (test for overall trend, P < 0.001). While the effects of intensive blood pressure control on HF event risk appeared to attenuate at lower eGFR and higher UACR, there was no significant interaction between eGFR or UACR and blood pressure control strategy (continuous and categorical interaction P > 0.05).

CONCLUSION

In SPRINT, eGFR and albuminuria were strong and additive determinants in forecasting HF risk. The effect of intensive blood pressure control in decreasing HF risk did not significantly vary across the spectrum of kidney function or albuminuria. Multidisciplinary pathways, incorporating blood pressure control, are needed for at-risk patients with chronic kidney disease to attenuate HF risk.

TRIAL REGISTRATION

ClinicalTrials.gov Identifier NCT01206062.

Intensive BP Control and eGFR Declines: Are These Events Due to Hemodynamic Effects and Are Changes Reversible?

PURPOSE OF REVIEW

Acute declines in estimated glomerular filtration rate (eGFR) are often observed during intensive blood pressure (BP) lowering. This review focuses on identifying the various mechanisms of eGFR decline associated with intensive BP lowering and evaluates the evidence linking BP control with kidney and cardiovascular (CV) outcomes.

RECENT FINDINGS

In 2017, the American College of Cardiology and the American Heart Association (ACC/AHA) began recommending treatment of all individuals to a BP target of < 130/80 mmHg. Since then, multiple post hoc analyses of BP trials have associated intensive BP lowering with acute declines in kidney function and acute kidney injury; whether these represent reversible changes in the kidney is still debated. There is ample evidence that intensive BP lowering is associated with declines in eGFR. The clinical implications of these events remain unclear. Individualizing the risks and benefits of intensive BP therapy continues to be warranted.

Creatinine increase following initiation of antihypertensives is associated with cardiovascular risk: a nationwide cohort study

OBJECTIVE

Abrupt decline in renal function following initiation of renin-angiotensin system inhibitor is associated with increased risk of cardiovascular disease, but studies of other antihypertensive drugs are sparse. We investigated the risk of cardiovascular event associated with increased plasma creatinine after initiating first-line antihypertensive treatment.

METHODS

In a nationwide cohort study, we identified adult Danish primary care patients initiating either renin-angiotensin system inhibitor, calcium channel blocker or thiazide, between 2008 and mid-2018. Patients with prior end-stage renal disease, renal transplantation, or cardiovascular disease were excluded. Percentual plasma creatinine increase was calculated between the nearest creatinine measurement up to 1 year before redeeming the prescription (baseline), and the nearest measurement 90 days or less after (index). Multiple logistic regression and restricted cubic splines were applied to estimate the 6-month absolute risk of cardiovascular event (ischemic heart disease, heart failure or stroke) associated with this creatinine increase.

RESULTS

We included 20 789 patients. Within the first 6 months of follow-up, 283 (1.4%) cardiovascular events and 93 (0.4%) all-cause deaths were registered. With a creatinine increase of 0 and 30%, 6-month absolute risk [CI] of cardiovascular event was 1.4% [1.1-1.9] and 3.5% [2.4-5.2], respectively (in men aged 50-79 years with estimated glomerular filtration rate at least 60 ml/min per 1.73 m and no diabetes). Higher age and reduced renal function, but not the type of antihypertensive treatment, were associated with higher cardiovascular risk.

CONCLUSION

In primary care, patients initiating first-line antihypertensive treatment, an increase in plasma creatinine above 30% was associated with increased absolute 6-month risk of cardiovascular event.

Dietary sodium restriction decreases urinary NGAL in older adults with moderately elevated systolic blood pressure free from chronic kidney disease

Increased aortic stiffness may contribute to kidney damage by transferring excessive flow pulsatility to susceptible renal microvasculature, leading to constriction or vessel loss. We previously demonstrated that 5 weeks of dietary sodium restriction (DSR) reduces large-elastic artery stiffness as well as blood pressure in healthy middle-aged/older adults with moderately elevated systolic blood pressure (SBP) who are free from chronic kidney disease (CKD). We hypothesized that DSR in this cohort would also reduce urinary concentrations of renal tubular injury biomarkers, which predict incident CKD in the general population. We performed a post hoc analysis using stored 24 hours urine samples collected in 13 participants as part of a randomized, double-blind, crossover clinical trial of DSR (low sodium (LS) target: 50 mmol/day; normal sodium (NS) target: 150 mmol/day). Participants were 61±2 (mean±SEM) years (8 M/5 F) with a baseline blood pressure of 139±2/82±2 mm Hg and an estimated glomerular filtration rate of 79±3 mL/min/1.73 m² Twenty-four hour urinary sodium excretion was reduced from 149±7 to 66±8 mmol/day during week 5. Despite having preserved kidney function, participants had a 31% reduction in urinary neutrophil gelatinase-associated lipocalin concentrations with just 5 weeks of DSR (LS: 2.8±0.6 vs NS: 4.2±0.8 ng/mL, p<0.05). Results were similar when normalized to urinary creatinine (urinary creatinine did not change between conditions). Concentrations of another kidney tubular injury biomarker, kidney injury molecule-1, were below the detectable limit in all but one sample. In conclusion, DSR reduces an established clinical biomarker of kidney tubular damage in adults with moderately elevated SBP who are free from prevalent kidney disease.

Effects of Intensive Blood Pressure Control in Patients with and without Albuminuria: Post Hoc Analyses from SPRINT

BACKGROUND AND OBJECTIVES

It is unclear whether the presence of albuminuria modifies the effects of intensive systolic BP control on risk of eGFR decline, cardiovascular events, or mortality.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

The Systolic Blood Pressure Intervention Trial randomized nondiabetic adults ≥50 years of age at high cardiovascular risk to a systolic BP target of <120 or <140 mm Hg, measured by automated office BP. We compared the absolute risk differences and hazard ratios of ≥40% eGFR decline, the Systolic Blood Pressure Intervention Trial primary cardiovascular composite outcome, and all-cause death in those with or without baseline albuminuria (urine albumin-creatinine ratio ≥30 mg/g).

RESULTS

Over a median follow-up of 3.1 years, 69 of 1723 (4%) participants with baseline albuminuria developed ≥40% eGFR decline compared with 61 of 7162 (1%) participants without albuminuria. Incidence rates of ≥40% eGFR decline were higher in participants with albuminuria (intensive, 1.74 per 100 person-years; standard, 1.17 per 100 person-years) than in participants without albuminuria (intensive, 0.48 per 100 person-years; standard, 0.11 per 100 person-years). Although effects of intensive BP lowering on ≥40% eGFR decline varied by albuminuria on the relative scale (hazard ratio, 1.48; 95% confidence interval, 0.91 to 2.39 for albumin-creatinine ratio ≥30 mg/g; hazard ratio, 4.55; 95% confidence interval, 2.37 to 8.75 for albumin-creatinine ratio <30 mg/g; P value for interaction <0.001), the absolute increase in ≥40% eGFR decline did not differ by baseline albuminuria (incidence difference, 0.38 events per 100 person-years for albumin-creatinine ratio ≥30 mg/g; incidence difference, 0.58 events per 100 person-years for albumin-creatinine ratio <30 mg/g; P value for interaction =0.60). Albuminuria did not significantly modify the beneficial effects of intensive systolic BP lowering on cardiovascular events or mortality evaluated on relative or absolute scales.

CONCLUSIONS

Albuminuria did not modify the absolute benefits and risks of intensive systolic BP lowering.

High Blood Pressure Is Associated with Tubulointerstitial Damage along with Glomerular Damage in Glomerulonephritis. A large Cohort Study

The key role of arterial hypertension in chonic kidney disease (CKD) progression is widely recognized, but its contribution to tubulointerstitial damage (TID) in glomerulonephritis (GN) remains uncertain. Hence, the objective of this study is to clarify whether TID is associated with glomerular damage, and whether the damage at the tubulointerstitial compartment is more severe in hypertensive patients. The study included retrospectively consecutive patients referred to the Nephrology Unit with diagnoses of primary glomerulonephritis, lupus nephritis (LN), and nephroangiosclerosis (NAS) at biopsy. At least six glomeruli per biopsy were analysed through light and immunofluorescence microscopy. Global glomerulosclerosis (GGS%), TID, and arteriolar hyalinosis (AH) were used as markers of CKD severity. Of the 448 patients of the cohort, 403 received a diagnosis of GN, with the remaining being diagnosed with NAS. Hypertension was found in 52% of the overall patients, with no significant differences among those with GN, and reaching 88.9% prevalence rate in NAS. The hypertensive patients with GN had more marked damage in glomerular and tubular compartments than normotensives independently of the amount of proteinuria. Moreover, hypertension and GGS% were found to be strongly associated with TID in GN. In GN patients, not only the severity of glomerular damage but also the extent of TID was associated with high blood pressure.

Associations of Systolic Blood Pressure With Incident CKD G3-G5: A Cohort Study of South Korean Adults

RATIONALE & OBJECTIVE

Clinical practice guidelines recommend a target blood pressure (BP)<130/80 mm Hg to reduce cardiovascular risk. However, the optimal BP to prevent chronic kidney disease (CKD) is unknown.

STUDY DESIGN

Population-based retrospective cohort study.

SETTING & PARTICIPANTS

10.5 million adults who participated in the National Health Insurance Service National Health Checkup Program in South Korea between 2009 and 2015 and had an estimated glomerular filtration rate (GFR) ≥ 60 mL/min/1.73 m² at the beginning of follow-up.

PREDICTORS

Baseline and time-updated systolic BP (SBP) as a continuous variable and categorized as<110, 110 to 119, 120 to 129, 130 to 139, or≥140 mm Hg.

OUTCOME

Incident CKD GFR categories 3 to 5 (CKD G3-G5), defined as de novo development of estimated GFR<60 mL/min/1.73 m² for at least 2 consecutive assessments confirmed at least 90 days apart.

ANALYTICAL APPROACH

Cox proportional hazards regression for baseline BP and marginal structural analysis for time-updated BP.

RESULTS

During 49,169,311 person-years of follow-up, incident CKD G3-G5 developed in 172,423 (1.64%) individuals with a crude event rate of 3.51 (95% CI, 3.49-3.52) per 1,000 person-years. Compared to a baseline SBP of 120 to 129 mm Hg, HRs for incident CKD G3-G5 for the<110, 110 to 119, 130 to 139, and≥140 mm Hg categories were 0.84 (95% CI, 0.82-0.85), 0.92 (95% CI, 0.91-0.94), 1.11 (95% CI, 1.09-1.12), and 1.30 (95% CI, 1.28-1.31), respectively. For time-updated SBPs, corresponding HRs were 0.57 (95% CI, 0.56-0.59), 0.79 (95% CI, 0.78-0.80), 1.58 (95% CI, 1.55-1.60), and 2.49 (95% CI, 2.45-2.53), respectively. Treated as a continuous exposure, each 10-mm Hg higher SBP was associated with 35% higher risk for incident CKD G3-G5 (95% CI, 1.35-1.36).

LIMITATIONS

Use of International Classification of Diseases codes to assess comorbid condition burden; residual confounding, and potential selection bias cannot be excluded.

CONCLUSIONS

In this large national cohort study, higher SBPs were associated with higher risk for incident CKD G3-G5. These findings support evaluation of SBP-lowering strategies to reduce the development of CKD.

The global epidemiology of hypertension

Hypertension is the leading cause of cardiovascular disease and premature death worldwide. Owing to the widespread use of antihypertensive medications, global mean blood pressure (BP) has remained constant or has decreased slightly over the past four decades. By contrast, the prevalence of hypertension has increased, especially in low- and middle-income countries (LMICs). Estimates suggest that 31.1% of adults (1.39 billion) worldwide had hypertension in 2010. The prevalence of hypertension among adults was higher in LMICs (31.5%, 1.04 billion people) than in high-income countries (28.5%, 349 million people). Variations in the levels of risk factors for hypertension, such as high sodium intake, low potassium intake, obesity, alcohol consumption, physical inactivity and unhealthy diet, may explain some of the regional heterogeneity in hypertension prevalence. Despite the increasing prevalence, the proportions of hypertension awareness, treatment and BP control are low, particularly in LMICs, and few comprehensive assessments of the economic impact of hypertension exist. Future studies are warranted to test implementation strategies for hypertension prevention and control, especially in low-income populations, and to accurately assess the prevalence and financial burden of hypertension worldwide.

C-X-C motif chemokine receptor 4 aggravates renal fibrosis through activating JAK/STAT/GSK3β/β-catenin pathway

Chronic kidney disease (CKD) has a high prevalence worldwide. Renal fibrosis is the common pathological feature in various types of CKD. However, the underlying mechanisms are not determined. Here, we adopted different CKD mouse models and cultured human proximal tubular cell line (HKC-8) to examine the expression of C-X-C motif chemokine receptor 4 (CXCR4) and β-catenin signalling, as well as their relationship in renal fibrosis. In CKD mice and humans with a variety of nephropathies, CXCR4 was dramatically up-regulated in tubules, with a concomitant activation of β-catenin. CXCR4 expression level was positively correlated with the expression of β-catenin target MMP-7. AMD3100, a CXCR4 receptor blocker, and gene knockdown of CXCR4 significantly inhibited the activation of JAK/STAT and β-catenin signalling, protected against tubular injury and renal fibrosis. CXCR4-induced renal fibrosis was inhibited by treatment with ICG-001, an inhibitor of β-catenin signalling. In HKC-8 cells, overexpression of CXCR4 induced activation of β-catenin and deteriorated cell injury. These effects were inhibited by ICG-001. Stromal cell-derived factor (SDF)-1α, the ligand of CXCR4, stimulated the activation of JAK2/STAT3 and JAK3/STAT6 signalling in HKC-8 cells. Overexpression of STAT3 or STAT6 decreased the abundance of GSK3β mRNA. Silencing of STAT3 or STAT6 significantly blocked SDF-1α-induced activation of β-catenin and fibrotic lesions. These results uncover a novel mechanistic linkage between CXCR4 and β-catenin activation in renal fibrosis in association with JAK/STAT/GSK3β pathway. Our studies also suggest that targeted inhibition of CXCR4 may provide better therapeutic effects on renal fibrosis by inhibiting multiple downstream signalling cascades.

Blood pressure targets and kidney and cardiovascular disease: same data but discordant guidelines

PURPOSE OF REVIEW

Hypertension is highly prevalent in the United States and a major risk factor for the development of cardiovascular disease. Hypertension is common in chronic kidney disease (CKD), and likely contributes to the association between CKD and cardiovascular disease. The ideal systolic BP to reduce cardiovascular disease risk in individuals with CKD is controversial.

RECENT FINDINGS

Several societies have released guidelines on the treatment of hypertension in the past year, each differing in important aspects, including BP targets. The release of new guidelines was largely spurred by the results of Systolic Blood Pressure Intervention Trial (SPRINT), which suggested mortality benefit with more intensive BP targets. Recent post-hoc analyses of a subgroup of ACCORD-BP participants suggest a benefit with tighter BP control. However, another post-hoc analysis of ACCORD-BP participants showed worse kidney outcomes with tighter BP control.

SUMMARY

Lower target BP appears associated with lower mortality in CKD, although longer term benefits with regard to kidney function remain unclear. Within this framework, treatment of hypertension should be tailored to each individual patient, accounting for cardiovascular disease risk, medication tolerance, and individual patient goals.

Urine Markers of Kidney Tubule Cell Injury and Kidney Function Decline in SPRINT Trial Participants with CKD

BACKGROUND AND OBJECTIVES

eGFR and albuminuria primarily reflect glomerular function and injury, whereas tubule cell atrophy and interstitial fibrosis on kidney biopsy are important risk markers for CKD progression. Kidney tubule injury markers have primarily been studied in hospitalized AKI. Here, we examined the association between urinary kidney tubule injury markers at baseline with subsequent loss of kidney function in persons with nondiabetic CKD who participated in the Systolic Blood Pressure Intervention Trial (SPRINT).

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

Among 2428 SPRINT participants with CKD (eGFR<60 ml/min per 1.73 m²) at baseline, we measured urine markers of tubule injury (IL-18, kidney injury molecule-1 [KIM-1], neutrophil gelatinase-associated lipocalin [NGAL]), inflammation (monocyte chemoattractant protein-1 [MCP-1]), and repair (human cartilage glycoprotein-40 [YKL-40]). Cox proportional hazards models evaluated associations of these markers with the kidney composite outcome of 50% eGFR decline or ESKD requiring dialysis or kidney transplantation, and linear mixed models evaluated annualized change in eGFR.

RESULTS

Mean participant age was 73±9 (SD) years, 60% were men, 66% were white, and mean baseline eGFR was 46±11 ml/min per 1.73 m². There were 87 kidney composite outcome events during a median follow-up of 3.8 years. Relative to the respective lowest quartiles, the highest quartiles of urinary KIM-1 (hazard ratio, 2.84; 95% confidence interval [95% CI], 1.31 to 6.17), MCP-1 (hazard ratio, 2.43; 95% CI, 1.13 to 5.23), and YKL-40 (hazard ratio, 1.95; 95% CI, 1.08 to 3.51) were associated with higher risk of the kidney composite outcome in fully adjusted models including baseline eGFR and urine albumin. In linear analysis, urinary IL-18 was the only marker associated with eGFR decline (-0.91 ml/min per 1.73 m² per year for highest versus lowest quartile; 95% CI, -1.44 to -0.38), a finding that was stronger in the standard arm of SPRINT.

CONCLUSIONS

Urine markers of tubule cell injury provide information about risk of subsequent loss of kidney function, beyond the eGFR and urine albumin.

Benefits and Risks of Continuing Angiotensin-Converting Enzyme Inhibitors, Angiotensin II Receptor Antagonists, and Mineralocorticoid Receptor Antagonists during Hospitalizations for Acute Heart Failure

BACKGROUND

The renin-angiotensin-aldosterone axis plays a pivotal role in the pathophysiology of acute and chronic heart failure (HF) and represents an important target for guideline-directed medical therapy.

SUMMARY

The use of appropriate directed medical therapies for inhibition of the renin-angiotensin-aldosterone axis in chronic HF has been the subject of several landmark clinical trials, with high levels of adherence exhibited in the outpatient setting. However, less clarity exists with respect to the initiation, continuation, and cessation of renin-angiotensin-aldosterone system inhibitors (RAASi) in the setting of acute HF and exacerbation of HF necessitating hospitalization. In this review, we summarize relevant aspects of the physiology of the renin-angiotensin-aldosterone axis in acute HF and during decongestion. We also summarize the available evidence for the risks and benefits of initiating and continuing RAASi in acute HF. Key Message: We offer a decision-making pathway for the use of RAASi in the setting of acute HF that would help guide the cardiologist and nephrologist caring for patients with acute HF and cardiorenal syndrome.

The influence of blood pressure patterns on renal outcomes in patients with chronic kidney disease: The long-term follow up result of the APrODiTe-2 study

Blood pressure (BP) control is the most established practice for preventing the progression and complications of chronic kidney disease (CKD). We examined the influence of BP patterns on target organ damage in hypertensive patients with CKD by using long-term follow-up data of the APrODiTe-2 study.We collected 5 years of data of APrODiTe-2 study (1 year longitudinal study) participants after the enrollment on the progression of estimated glomerular filtration (eGFR), renal outcomes (doubling of serum creatinine, 50% decrease of eGFR, maintenance dialysis, and kidney transplantation), cerebro-cardiovascular (CCV) accidents, and all-cause mortality (n=378) to evaluate the long-term influence of BP patterns on target organ damages.Initially, more than 2/3 of patients showed masked (50.0%) and sustained uncontrolled (30.6%) BP control states as well as non- (31.3%) and reverse-dipping (35.0%) states. Only 18.8% and 20.8% of participants showed a better change in BP control patterns and a dipping pattern change to dippers over 1 year, respectively. Composite of new CCV accidents occurred in 43 patients (11.4%), and no BP patterns were associated with the occurrence of new CCV accidents. A worse change in BP control categories over 1 year was associated with increased occurrence of composites of renal outcomes after adjustment for age, sex, and the cause of CKD (HR 5.997 [1.454-24.742], P = .013 and HR 4.331 [1.347-13.927], P = .014, respectively). Patients with a worse initial BP control category, a worse change in BP control categories over 1 year, and higher clinic systolic BP and pulse pressure (PP) (> median level) were more likely to have faster eGFR progression (absolute eGFR and eGFR ratio).Higher BP burden (a worse change in BP control categories, higher initial clinic systolic BP and PP) was associated with faster eGFR progression and increased occurrence of renal outcomes.

Management of Presumed Acute Kidney Injury during Hypertensive Therapy: Stay Calm and Carry on?

BACKGROUND

Recent studies have demonstrated that intensive blood pressure control is associated with improved cardiovascular outcomes. Acute kidney injury (AKI), however, was more common in the intensive treatment group prompting concern in the nephrology community.

SUMMARY

Clinical trials on hypertension control have traditionally defined AKI by changes in serum creatinine. However, serum creatinine has several inherent limitations as a marker of kidney injury, with various factors influencing its production, secretion, and elimination. Urinary biomarkers of kidney injury and repair have the potential to provide insight on the presence and phenotype of kidney injury. In both the Systolic Blood Pressure Intervention Trial and the Action to Control Cardiovascular Risk in Diabetes study, urinary biomarkers have suggested that the increased risk of AKI associated with intensive treatment was due to hemodynamic changes rather than structural kidney injury. As such, clinicians who encounter rises in serum creatinine during intensification of hypertension therapy should "stay calm and carry on." Alternative explanations for serum creatinine elevation should be considered and addressed if appropriate. When the rise in serum creatinine is limited, particularly if albuminuria is stable or improving, intensive blood pressure control should be continued for its potential long-term benefits. Key Messages: Increases in serum creatinine during intensification of blood pressure control may not necessarily reflect kidney injury. Clinicians should evaluate for other contributing factors before stopping therapy. Urinary biomarkers may address limitations of serum creatinine as a marker of kidney injury.

11. Microvascular Complications and Foot Care: Standards of Medical Care in Diabetes-2020

The American Diabetes Association (ADA) "Standards of Medical Care in Diabetes" includes the ADA's current clinical practice recommendations and is intended to provide the components of diabetes care, general treatment goals and guidelines, and tools to evaluate quality of care. Members of the ADA Professional Practice Committee, a multidisciplinary expert committee (https://doi.org/10.2337/dc20-SPPC), are responsible for updating the Standards of Care annually, or more frequently as warranted. For a detailed description of ADA standards, statements, and reports, as well as the evidence-grading system for ADA's clinical practice recommendations, please refer to the Standards of Care Introduction (https://doi.org/10.2337/dc20-SINT). Readers who wish to comment on the Standards of Care are invited to do so at professional.diabetes.org/SOC.

Optimal blood pressure target and measurement in patients with chronic kidney disease

The prevalence rates of hypertension and chronic kidney disease (CKD) are increasing with the aging of the population. Hypertension and CKD are closely related, and hypertension with accompanying CKD is difficult to control. This difficulty controlling blood pressure (BP) can be explained by changes in diurnal variation in BP, such as non-dipping and reverse dipping patterns, increased pulse pressure, and BP variability in CKD patients resulting in a high frequency of nocturnal hypertension or masked hypertension. CKD patients with uncontrolled or nocturnal hypertension are at increased risk for cardiovascular disease, progression of CKD, and all-cause death. Recent studies have shown that intensive reduction of systolic BP below 120 mmHg is seems to favor in CKD patients regardless of the presence or absence of diabetes. As BP control is difficult in patients with CKD, appropriate measurement of BP is important. Automated BP monitoring could reduce the so-called "white coat effect" (spike in BP) that may be triggered by measurement in a clinical setting. Moreover, out-of-office BP monitoring at home or ambulatory BP monitoring for 24 hours may provide critical information regarding diurnal BP variability and nocturnal BP in patients with CKD.

Does Chronic Kidney Disease Predict Stroke Risk Independent of Blood Pressure?: A Systematic Review and Meta-Regression

Background and Purpose- Chronic kidney disease is strongly associated with stroke with various purported mechanisms proposed. Low glomerular filtration rate appears to be a risk factor for stroke independent of cardiovascular risk factors in epidemiological studies, but there has been no systematic assessment of the impact of more complete adjustment for blood pressure on the association. Methods- We did a systematic review to February 2018 (MEDLINE/EMBASE) for cohort studies or randomized controlled trials that reported stroke incidence in adults according to baseline estimated glomerular filtration rate. Study and participant characteristics and relative risks (RR) were extracted. Estimates were combined using a random-effects model. Heterogeneity was assessed by x2 statistics and I2 and by subgroup strata and meta-regression. Results- We identified 168 studies reporting data on 5 611 939 participants with 115 770 stroke outcomes. Eighty-five studies (3 417 098 participants; 72 996 strokes) provided adequate data for meta-analysis of estimated glomerular filtration rate and stroke risk. Incident stroke risk was increased among participants with estimated glomerular filtration rate <60 mL/min per 1.73 m2 (RR=1.73; 95% CI, 1.57-1.90; P<0.001), but there was substantial heterogeneity between studies (P<0.0001; I2, 78.5%). Moreover, the association was reduced after adjustment for cardiovascular risk factors, with progressive attenuation on more thorough adjustment for hypertension: single baseline blood pressure measure (RR=1.63; CI, 1.34-1.99; P<0.001); history or treated hypertension (RR=1.35; CI, 1.24-1.46; P<0.001); multiple blood pressure measurements over months to years (RR=1.10; CI, 1.02-1.18; P=0.01). Conclusions- The association between chronic kidney disease and stroke appears to be highly dependent on the method of adjustment for hypertension. The apparently independent relationship between chronic kidney disease and stroke may be confounded by their shared association with long-term prior blood pressure.

Disrupted tubular parathyroid hormone/parathyroid hormone receptor signaling and damaged tubular cell viability possibly trigger postsurgical kidney injury in patients with advanced hyperparathyroidism

BACKGROUND

Parathyroidectomy (PTX) that alleviates clinical manifestations of advanced hyperparathyroidism, including hypercalcemia and hypophosphatemia, is considered the best protection from calcium overload in the kidney. However, little is known about the relationship between postsurgical robust parathyroid hormone (PTH) reduction and perisurgical renal tubular cell viability. Post-PTX kidney function is still a crucial issue for primary hyperparathyroidism (PHPT) and tertiary hyperparathyroidism after kidney transplantation (THPT).

METHODS

As a clinical study, we examined data from 52 consecutive patients (45 with PHPT, 7 with THPT) who underwent PTX in our center between 2015 and 2017 to identify post-PTX kidney injury. Their clinical data, including urinary liver-type fatty acid-binding protein (L-FABP), a tubular biomarker for acute kidney injury (AKI), were obtained from patient charts. An absolute change in serum creatinine level of 0.3 mg/dL (26.5 µmol/L) on Day 2 after PTX defines AKI. Post-PTX calcium supplement dose adjustment was performed to strictly maintain serum calcium at the lower half of the normal range. To mimic post-PTX-related kidney status, a unique parathyroidectomized rat model was produced as follows: 13-week-old rats underwent thyroparathyroidectomy (TPTX) and/or 5/6 subtotal nephrectomy (NX). Indicated TPTX rats were given continuous infusion of a physiological level of 1-34 PTH using a subcutaneously implanted osmotic minipump. Immunofluorescence analyses were performed by polyclonal antibodies against PTH receptor (PTHR) and a possible key modulator of kidney injury, Klotho.

RESULTS

Patients' estimated glomerular filtration rate (eGFR) did not have any clinically relevant change (62.5 ± 22.0 versus 59.4 ± 21.9 mL/min/1.73 m2, NS), whereas serum calcium (2.7 ± 0.18 versus 2.2 ± 0.16 mmol/L, P < 0.0001) and phosphorus levels (0.87 ± 0.19 versus 1.1 ± 0.23 mmol/L, P < 0.0001) were normalized and PTH decreased robustly (181 ± 99.1 versus 23.7 ± 16.8 pg/mL, P < 0.0001) after successful PTX. However, six patients who met postsurgical AKI criteria had lower eGFR and greater L-FABP than those without AKI. Receiver operating characteristics (ROC) analysis revealed eGFR <35 mL/min/1.73 m2 had 83% accuracy. Strikingly, L-FABP >9.8 µg/g creatinine had 100% accuracy in predicting post-PTX-related AKI. Rat kidney PTHR expression was lower in TPTX. PTH infusion (+PTH) restored tubular PTHR expression in rats that underwent TPTX. Rats with TPTX, +PTH and 5/6 NX had decreased PTHR expression compared with those without 5/6 NX. 5/6 NX partially cancelled tubular PTHR upregulation driven by +PTH. Tubular Klotho was modestly expressed in normal rat kidneys, whereas enhanced patchy tubular expression was identified in 5/6 NX rat kidneys. This Klotho and expression and localization pattern was absolutely canceled in TPTX, suggesting that PTH indirectly modulated the Klotho expression pattern. TPTX +PTH recovered tubular Klotho expression and even triggered diffusely abundant Klotho expression. 5/6 NX decreased viable tubular cells and eventually downregulated tubular Klotho expression and localization.

CONCLUSIONS

Preexisting tubular damage is a potential risk factor for AKI after PTX although, overall patients with hyperparathyroidism are expected to keep favorable kidney function after PTX. Patients with elevated tubular cell biomarker levels may suffer post-PTX kidney impairment even though calcium supplement is meticulously adjusted after PTX. Our unique experimental rat model suggests that blunted tubular PTH/PTHR signaling may damage tubular cell viability and deteriorate kidney function through a Klotho-linked pathway.

Heart Failure and Changes in Kidney Function: Focus on Understanding, Not Reacting

The kidney is a regulatory organ and accommodates changes in cardiac function. There is cross-talk between the kidney and the heart. In heart failure, the kidney acts as a bystander but also contributes to several maladaptive processes. The pathophysiology of worsening kidney function and its association with prognosis are discussed, as are other aspects of how worsening kidney function contributes to increased cardiovascular risk. Data suggest that morbidity and mortality reduction in people with heart failure and kidney disease requires use of a renin angiotensin system blocker, beta blocker, and mineralocorticoid receptor antagonist, as well as an SGLT 2 inhibitor.

New Insights Into Mechanisms of Acute Kidney Injury in Heart Disease

Acute kidney injury is a frequent occurrence in patients with heart disease, and is associated with higher risk of adverse outcomes, including mortality. In the setting of decompensated heart failure, acute kidney injury can occur from hemodynamic and neurohormonal activation, venous congestion, and nephrotoxic medications. Certain medications, such as loop diuretics, renin angiotensin system blockers, and mineralocorticoid antagonists can seemingly cause acute kidney injury. However, this increase in creatinine level is not always associated with adverse outcomes and should be carefully differentiated so as to allow deliberate continuation of these cardio- and nephroprotective agents. In other settings such as cardiac surgery, acute kidney injury can occur from factors related to the cardiopulmonary bypass, renal hypoperfusion, or other perioperative factors. Last, patients with heart disease commonly undergo imaging procedures that require contrast administration. Contrast can indeed cause acute kidney injury, but these interventional procedures also can result in kidney injury from atheroembolic phenomena. This is well documented by the recent data reporting a higher risk of acute kidney injury from femoral compared with radial access. The advent of biomarkers of kidney injury present an opportunity for early detection, accurate differential diagnosis, as well as potentially designing innovative biomarker-enriched adaptive clinical trials.

Effect of Intensive Blood Pressure Lowering on Kidney Tubule Injury: Findings From the ACCORD Trial Study Participants

RATIONALE & OBJECTIVE

Random assignment to intensive blood pressure (BP) lowering (systolic BP<120mmHg) compared to a less intensive BP target (systolic BP<140mmHg) in the Action to Control Cardiovascular Risk in Diabetes BP (ACCORD-BP) trial resulted in a more rapid decline in estimated glomerular filtration rate (eGFR). Whether this reflects hemodynamic effects or intrinsic kidney damage is unknown.

STUDY DESIGN

Longitudinal analysis of a subgroup of clinical trial participants.

SETTINGS & PARTICIPANTS

A subgroup of 529 participants in ACCORD-BP.

EXPOSURES

Urine biomarkers of tubular injury (kidney injury molecule 1, interleukin 18 [IL-18]), repair (human cartilage glycoprotein 39 [YKL-40]), and inflammation (monocyte chemoattractant protein 1) at baseline and year 2.

OUTCOMES

Changes in eGFR from baseline to 2 years.

ANALYTICAL APPROACH

We compared changes in biomarker levels and eGFRs across participants treated to an intensive versus less intensive BP goal using analysis of covariance.

RESULTS

Of 529 participants, 260 had been randomly assigned to the intensive and 269 to the standard BP arm. Mean age was 62±6.5 years and eGFR was 90mL/min/1.73m2. Baseline clinical characteristics, eGFRs, urinary albumin-creatinine ratios (ACRs), and urinary biomarker levels were similar across BP treatment groups. Compared to less intensive BP treatment, eGFR was 9.2mL/min/1.73m2 lower in the intensive BP treatment group at year 2. Despite the eGFR reduction, within this treatment group, ACR was 30% lower and 4 urinary biomarker levels were unchanged or lower at year 2. Also within this group, participants with the largest declines in eGFRs had greater reductions in urinary IL-18 and YKL-40 levels. In a subgroup analysis of participants developing incident chronic kidney disease (sustained 30% decline and eGFR<60mL/min/1.73m2; n=77), neither ACR nor 4 biomarker levels increased in the intensive treatment group, whereas the level of 1 biomarker, IL-18, increased in the less intensive treatment group.

LIMITATIONS

Few participants with advanced baseline chronic kidney disease. Comparisons across treatment groups do not represent comparisons of treatment arms created solely through randomization.

CONCLUSIONS

Among a subset of ACCORD-BP trial participants, intensive BP control was associated with reductions in eGFRs, but not with an increase in injury marker levels. These findings support that eGFR decline observed with intensive BP goals in ACCORD participants may predominantly reflect hemodynamic alterations.

Blood Pressure Goals in Patients with CKD: A Review of Evidence and Guidelines

Hypertension affects the vast majority of patients with CKD and increases the risk of cardiovascular disease, ESKD, and death. Over the past decade, a number of hypertension guidelines have been published with varying recommendations for BP goals in patients with CKD. Most recently, the American College of Cardiology/American Heart Association 2017 hypertension guidelines set a BP goal of <130/80 mm Hg for patients with CKD and others at elevated cardiovascular risk. These guidelines were heavily influenced by the landmark Systolic Blood Pressure Intervention Trial (SPRINT), which documented that an intensive BP goal to a systolic BP <120 mm Hg decreased the risk of cardiovascular disease and mortality in nondiabetic adults at high cardiovascular risk, many of whom had CKD; the intensive BP goal did not retard CKD progression. It is noteworthy that SPRINT measured BP with automated devices (5-minute wait period, average of three readings) often without observers, a technique that potentially results in BP values that are lower than what is typically measured in the office. Still, results from SPRINT along with long-term follow-up data from the Modification of Diet in Renal Disease and the African American Study of Kidney Disease and Hypertension suggest that a BP goal <130/80 mm Hg will reduce mortality in patients with CKD. Unfortunately, data are more limited in patients with diabetes or stage 4-5 CKD. Increased adverse events, including electrolyte abnormalities and decreased eGFR, necessitate careful laboratory monitoring. In conclusion, a BP goal of <130/80 is a reasonable, evidence-based BP goal in patients with CKD. Implementation of this intensive BP target will require increased attention to measuring BP accurately, assessing patient preferences and concurrent medical conditions, and monitoring for adverse effects of therapy.