Renal denervation: recent developments in clinical and preclinical research

PURPOSE OF REVIEW

Renal denervation represents a new dimension to hypertension treatment, with multiple device manufacturers seeking premarket FDA approval currently. Interest in the efficacy and safety of the treatment has spurred compelling mechanistic studies into the function of renal nerves and downstream impacts of denervation.

RECENT FINDINGS

A trial of the ultrasound Paradise Catheter system (RADIANCE II) found a 6.3 mmHg reduction in SBP relative to sham controls. A trial of the Symplicity Spyral system (SPYRAL HTN-ON MED) found an insignificant reduction in SBP relative to sham controls. Individuals were taking antihypertensive medications during the study, and investigators note the sham group experienced a larger medication burden than the denervated group. Recent preclinical studies have evaluated potential risks of renal denervation, how sympathetic activity broadly is affected, as well as identifying possible biomarkers to identify individuals where denervation would be more successful.

SUMMARY

Studies of renal denervation continue to find a robust antihypertensive effect, especially in studies wherein medications are withdrawn. Further investigation into mechanisms and indicators for usage of the technique will be important in identifying the patient population most likely to benefit from usage of renal denervation.

Probing the Association between Acute Kidney Injury and Cardiovascular Outcomes

BACKGROUND

Patients hospitalized with AKI have higher subsequent risks of heart failure, atherosclerotic cardiovascular events, and mortality than their counterparts without AKI, but these higher risks may be due to differences in prehospitalization patient characteristics, including the baseline level of estimated glomerular filtration rate (eGFR), the rate of prior eGFR decline, and the proteinuria level, rather than AKI itself.

METHODS

Among 2177 adult participants in the Chronic Renal Insufficiency Cohort study who were hospitalized in 2013-2019, we compared subsequent risks of heart failure, atherosclerotic cardiovascular events, and mortality between those with serum creatinine-based AKI (495 patients) and those without AKI (1682 patients). We report both crude associations and associations sequentially adjusted for prehospitalization characteristics including eGFR, eGFR slope, and urine protein-creatinine ratio (UPCR).

RESULTS

Compared with patients hospitalized without AKI, those with hospitalized AKI had lower eGFR prehospitalization (42 versus 49 ml/min per 1.73 m 2 ), faster chronic loss of eGFR prehospitalization (-0.84 versus -0.51 ml/min per 1.73 m 2 per year), and more proteinuria prehospitalization (UPCR 0.28 versus 0.16 g/g); they also had higher prehospitalization systolic BP (130 versus 127 mm Hg; P < 0.01 for all comparisons). Adjustment for prehospitalization patient characteristics attenuated associations between AKI and all three outcomes, but AKI remained an independent risk factor. Attenuation of risk was similar after adjustment for absolute eGFR, eGFR slope, or proteinuria, individually or in combination.

CONCLUSIONS

Prehospitalization variables including eGFR, eGFR slope, and proteinuria confounded associations between AKI and adverse cardiovascular outcomes, but these associations remained significant after adjusting for prehospitalization variables.

Protection from COVID-19 mRNA vaccination and prior SARS-CoV-2 infection against COVID-19-associated encounters in adults during Delta and Omicron predominance

BACKGROUND

Data assessing protection conferred from COVID-19 mRNA vaccination and/or prior SARS-CoV-2 infection during Delta and Omicron predominance periods in the U.S. are limited.

METHODS

This cohort study included persons ≥18 years who had ≥1 healthcare encounter across four health systems and had been tested for SARS-CoV-2 before August 26, 2021. COVID-19 mRNA vaccination and prior SARS-CoV-2 infection defined the exposure. Cox regression estimated hazard ratios (HRs) for the Delta and Omicron periods; protection was calculated as (1-HR)x100%.

RESULTS

Compared to unvaccinated and previously uninfected persons, during Delta predominance, protection against COVID-19-associated hospitalizations was high for those 2- or 3-dose vaccinated and previously infected, 3-dose vaccinated alone, and prior infection alone (range:91%-97%, with overlapping 95% confidence intervals (95%CIs)); during Omicron predominance, estimates were lower (range:77%-90%). Protection against COVID-19-associated emergency department/urgent care (ED/UC) encounters during Delta predominance was high for those exposure groups (range:86%-93%); during Omicron predominance, protection remained high for those 3-dose vaccinated with or without a prior infection (76% (95%CI=67%-83%) and 71% (95%CI=67%-73%), respectively).

CONCLUSIONS

COVID-19 mRNA vaccination and/or prior SARS-CoV-2 infection provided protection against COVID-19-associated hospitalizations and ED/UC encounters regardless of variant. Staying up-to-date with COVID-19 vaccination still provides protection against severe COVID-19 disease, regardless of prior infection.

Global proliferation and clinical consequences of non-validated automated BP devices

Professional societies, guideline writing committees, and other interested parties emphasize the importance of accurate measurement of blood pressure for clinical and public health decisions related to prevention, treatment, and follow-up of high blood pressure. Use of a clinically validated instrument to measure blood pressure is a central component of measurement accuracy and precision. Despite this, most regulatory authorities do not specify validation requirements that manufacturers must meet to sell their blood pressure measurement devices. Likewise, device validity is not a major area of focus for most consumers and healthcare providers, perhaps because they assume it is a pre-requisite for market approval. This has led to a global proliferation of non-validated blood pressure measurement devices, with only a small minority of blood pressure measurement devices having passed internationally accepted validation protocols. The clinical consequences are likely to be significant because non-validated devices are more likely to provide inaccurate estimates of blood pressure compared with validated devices. Even small inaccuracies in blood pressure measurement can result in substantial misdiagnosis and mistreatment of hypertension. There is an urgent need for clinical validation of blood pressure measurement devices prior to marketing them to consumers. There is also need for simplification of the process for consumers and healthcare providers to determine whether a blood pressure measurement device has successfully met an internationally accepted test of validity.

Kidney-Metabolic Factors Associated with Cognitive Impairment in Chronic Kidney Disease: A Pilot Study

INTRODUCTION

The associations of kidney-metabolic biomarkers with cognitive impairment (CI) beyond the estimated glomerular filtration rate (eGFR, in mL/min/1.73 m2) and albuminuria levels are not well understood. In exploratory analysis, our objective was to determine the extent that three kidney-metabolic factors, previously proposed as mechanisms of CI and commonly abnormal in chronic kidney disease (CKD), were associated with prevalent CI in CKD participants, adjusted for kidney function measures.

METHODS

The study cohort included community-dwelling individuals aged ≥45 years with CKD (eGFR <60), not requiring dialysis, recruited from four health systems. We examined the serum biomarkers bicarbonate (CO2), TNFαR1, and cholesterol as primary exposures. A structured neuropsychological battery conducted by trained staff measured global and domain-specific cognitive performance. Logistic regression analyses estimated the cross-sectional associations between kidney-metabolic measures and global and cognitive domain-specific moderate/severe (Mod/Sev) CI, adjusted for the eGFR, urinary albumin-creatinine ratio (UACR, mg/g), demographics, comorbid conditions, and other kidney-metabolic biomarkers commonly abnormal in CKD.

RESULTS

Among 436 CKD participants with mean age 70 years, 16% were Black, the mean eGFR was 34, and the median [IQR] UACR was 49 [0.0, 378] mg/g. In adjusted models, increased TNFαR1 was associated with global Mod/Sev CI (odds ratio [95% confidence interval] = 1.40 [1.02, 1.93]; p = 0.04); low bicarbonate (CO2 <20 mEq/L) with Mod/Sev memory impairment (3.04 [1.09, 8.47]; p = 0.03), and each 10-mg/dL lower cholesterol was associated with Mod/Sev executive function/processing speed impairment (1.12 [1.02, 1.23]; p = 0.02). However, after adjustment for multiple comparisons, these associations were no longer significant nor were any other kidney-metabolic factors significant for any CI classification.

CONCLUSION

In exploratory analyses in a CKD population, three kidney-metabolic factors were associated with CI, but after adjustment for multiple comparisons, were no longer significant. Future studies in larger CKD populations are needed to assess these potential risk factors for CI.

Potential impact of systematic and random errors in blood pressure measurement on the prevalence of high office blood pressure in the United States

The authors examined the proportion of US adults that would have their high blood pressure (BP) status changed if systolic BP (SBP) and diastolic BP (DBP) were measured with systematic bias and/or random error versus following a standardized protocol. Data from the 2017-2018 National Health and Nutrition Examination Survey (NHANES; n = 5176) were analyzed. BP was measured up to three times using a mercury sphygmomanometer by a trained physician following a standardized protocol and averaged. High BP was defined as SBP ≥130 mm Hg or DBP ≥80 mm Hg. Among US adults not taking antihypertensive medication, 32.0% (95%CI: 29.6%,34.4%) had high BP. If SBP and DBP were measured with systematic bias, 5 mm Hg for SBP and 3.5 mm Hg for DBP higher and lower than in NHANES, the proportion with high BP was estimated to be 44.4% (95%CI: 42.6%,46.2%) and 21.9% (95%CI 19.5%,24.4%). Among US adults taking antihypertensive medication, 60.6% (95%CI: 57.2%,63.9%) had high BP. If SBP and DBP were measured 5 and 3.5 mm Hg higher and lower than in NHANES, the proportion with high BP was estimated to be 71.8% (95%CI: 68.3%,75.0%) and 48.4% (95%CI: 44.6%,52.2%), respectively. If BP was measured with random error, with standard deviations of 15 mm Hg for SBP and 7 mm Hg for DBP, 21.4% (95%CI: 19.8%,23.0%) of US adults not taking antihypertensive medication and 20.5% (95%CI: 17.7%,23.3%) taking antihypertensive medication had their high BP status re-categorized. In conclusions, measuring BP with systematic or random errors may result in the misclassification of high BP for a substantial proportion of US adults.

Does experience matter? The relationship between nephrologist characteristics and end stage kidney disease patient outcomes

BACKGROUND

Nephrology offers the unique opportunity to directly link patients to providers, allowing the study of patient outcomes at the provider level. The purpose of this analysis was to determine whether nephrologist experience, defined as years in nephrology practice, was associated with clinical outcomes.

DESIGN

Physician data contained within the American Medical Association (AMA) Physician Masterfile was combined with patient and Medicare claims data from the United States Renal Data System (USRDS) for the calendar year 2012, with follow up extending through June 30, 2014. Associations with important healthcare outcomes including mortality in patients receiving maintenance renal replacement therapy (RRT), waitlisting for kidney transplantation, and receipt of a kidney transplant were determined with broad adjustment for both patient and provider level variables, with attention on tertile of provider time in practice.

RESULTS

We identified 256,324 patients on maintenance RRT cared for by 6193 nephrologists. Nephrologists with the least experience were more likely to be female, reside in a region with ≥1,000,000 people, have a Doctor of Osteopathic Medicine degree, and have a listed maintenance of certification status as "yes." Overall, 30.2% of the cohort died at a mean follow up of 1.99 years. Compared to those with the 0-10 years of experience, receipt of care from nephrologists with more experience was associated with lower mortality (AHR 0.97 CI 0.94-0.99 for nephrologists with 11-20 years) and increased listing for kidney transplantation (AHR 1.10; CI 1.01-1.21 for nephrologists with >21 years experience). Experience level did not result in a difference in kidney transplantation rates.

CONCLUSIONS

Receipt of maintenance RRT from nephrologists with greater experience was associated with decreased mortality and increased listing for kidney transplantation, an effect that remained significant after multiple adjustments for important patient and nephrologist variables.

Abstract P112: Orthostatic Hypotension, Orthostatic Hypertension And Ambulatory Blood Pressure In Patients With Chronic Kidney Disease: Findings From The Chronic Renal Insufficiency Cohort Study

Background: We recently demonstrated how orthostatic hypotension might be used to identify out-of-office blood pressure phenotypes, including white coat effects and nocturnal non-dipping patterns. However, these findings have not been replicated in a population with chronic kidney disease (CKD).

Objective: To examine the association between orthostatic hypotension (OH) or hypertension (OHTN) with ambulatory BP in adults with CKD.

Methods: CRIC is a prospective multicenter observation cohort study of participants with CKD. Standing BP at 1 minute and ABPM were obtained on 1467 participants. OH was defined as a 20mmHg drop in systolic BP (SBP) or 10 mmHg drop in diastolic BP (DBP) when changing from seated to standing positions. OHTN was defined as a 20 mmHg or 10mmHg rise in SBP or DBP respectively when changing from seated to standing position. White coat effects, based on ABPM, was defined as the difference between seated clinic and ambulatory BP. Systolic and diastolic night to day ratio was also calculated.

Results: Of the 1467 participants (age: 58 ± 10 yrs, 44% female, 39% black) 73 had OH and 165 had OHTN). OH was positively associated with systolic and diastolic white coat effect (β=5.9 [0.9, 10.9] and 4.2 [1.3, 7.1]). OHTN was negatively associated with diastolic white coat effect (-4.9 [-6.9, -3]). OH was positively associated with systolic and diastolic night-to-day ratio (0.03 [0.01, 0.05] and 0.03 [0.01, 0.06] respectively).

Conclusions: Clinic-based assessments of OH and OHTN may be useful for identifying BP phenotypes often missed with seated office BP measurements in CKD patients.

Mobile Health Intervention to Close the Guidelines-To-Practice Gap in Hypertension Treatment: Protocol for the mGlide Randomized Controlled Trial

Background

Suboptimal treatment of hypertension remains a widespread problem, particularly among minorities and socioeconomically disadvantaged groups. We present a health system–based intervention with diverse patient populations using readily available smartphone technology. This intervention is designed to empower patients and create partnerships between patients and their provider team to promote hypertension control.

Objective

The mGlide randomized controlled trial is a National Institutes of Health–funded study, evaluating whether a mobile health (mHealth)-based intervention that is an active partnership between interprofessional health care teams and patients results in better hypertension control rates than a state-of-clinical care comparison.

Methods

We are recruiting 450 participants including stroke survivors and primary care patients with elevated cardiovascular disease risk from diverse health systems. These systems include an acute stroke service (n=100), an academic medical center (n=150), and community medical centers including Federally Qualified Health Centers serving low-income and minority (Latino, Hmong, African American, Somali) patients (n=200). The primary aim tests the clinical effectiveness of the 6-month mHealth intervention versus standard of care. Secondary aims evaluate sustained hypertension control rates at 12 months; describe provider experiences of system usability and satisfaction; examine patient experiences, including medication adherence and medication use self-efficacy, self-rated health and quality of life, and adverse event rates; and complete a cost-effectiveness analysis.

Results

To date, we have randomized 107 participants (54 intervention, 53 control).

Conclusions

This study will provide evidence for whether a readily available mHealth care model is better than state-of-clinical care for bridging the guideline-to-practice gap in hypertension treatment in health systems serving diverse patient populations.

Trial Registration

Clinicaltrials.gov NCT03612271; https://clinicaltrials.gov/ct2/show/NCT03612271

International Registered Report Identifier (IRRID)

DERR1-10.2196/25424

Abstract P172: Orthostatic Hypotension And 24-hr Ambulatory Blood Pressure Monitoring In The Sprint Trial

Background: Clinic blood pressure (BP) is measured in the seated position, which can miss important home BP phenotypes such as low ambulatory BP (white coat effects) or high supine BP (nocturnal non-dippers). Orthostatic hypotension (OH) is determined based on BP measurements in both seated (or supine) and standing positions, and thus could theoretically identify these important phenotypes in clinic.

Objective: To determine the association of OH with white coat effects or night-to-daytime systolic BP (SBP)

Methods: SPRINT was a randomized trial testing the effects of intensive (<120 mmHg) or standard (<140 mmHg) SBP treatment strategies in adults at higher risk of cardiovascular disease. OH was assessed at 6, 12, or 24-mths and defined as a decrease in standing and mean seated SBP ≥20 or DBP ≥10 mmHg after 1 min of standing. White coat effects, based on 24-hr ambulatory BP monitoring performed at the 27-mth visit (every 30-minutes), were defined as the difference between 27-mth seated clinic and ambulatory BP ≥ 20/≥10 mmHg. SBP dipping ratio was defined as the ratio of night-to-daytime SBP >0.9.

Results: Of 897 adults (mean age 71.5 [SD, 9.5] yrs, 28.7% female, 28.0% black), 128 had OH at least once. Among those with OH, 14.8% had white coat effects versus 7.2% among those without OH. Moreover, 68.8% of those with OH demonstrated non-dipping patterns versus only 52.0% of those without OH. OH was positively associated with both white coat effects (OR=2.24; 95% CI: 1.28, 4.27) and higher night-to-daytime SBP (β=0.04; 95% CI: 0.02, 0.06) ( Table ).

Conclusions: Clinic-based assessments of OH may be a useful tool for identifying BP phenotypes often missed with traditional seated BP assessments.

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.

Development and Validation of a Pragmatic Electronic Phenotype for CKD

BACKGROUND AND OBJECTIVES

Poor identification of individuals with CKD is a major barrier to research and appropriate clinical management of the disease. We aimed to develop and validate a pragmatic electronic (e-) phenotype to identify patients likely to have CKD.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

The e-phenotype was developed by an expert working group and implemented among adults receiving in- or outpatient care at five healthcare organizations. To determine urine albumin (UA) dipstick cutoffs for CKD to enable use in the e-phenotype when lacking urine albumin-to-creatinine ratio (UACR), we compared same day UACR and UA results at four sites. A sample of patients, spanning no CKD to ESKD, was randomly selected at four sites for validation via blinded chart review.

RESULTS

The CKD e-phenotype was defined as most recent eGFR <60 ml/min per 1.73 m2 with at least one value <60 ml/min per 1.73 m2 >90 days prior and/or a UACR of ≥30 mg/g in the most recent test with at least one positive value >90 days prior. Dialysis and transplant were identified using diagnosis codes. In absence of UACR, a sensitive CKD definition would consider negative UA results as normal to mildly increased (KDIGO A1), trace to 1+ as moderately increased (KDIGO A2), and ≥2+ as severely increased (KDIGO A3). Sensitivity, specificity, and diagnostic accuracy of the CKD e-phenotype were 99%, 99%, and 98%, respectively. For dialysis sensitivity was 94% and specificity was 89%. For transplant, sensitivity was 97% and specificity was 91%.

CONCLUSIONS

The CKD e-phenotype provides a pragmatic and accurate method for EHR-based identification of patients likely to have CKD.

Time to thrombectomy is associated with increased risk for dialysis catheter placement

BACKGROUND

Arteriovenous dialysis access, fistulae (AVF) or grafts (AVG), are associated with significant rates of thrombosis. Timely thrombectomy may have a significant impact on immediate and long-term access survival. However, switching to a catheter is associated with higher rates of morbidity and mortality compared with those who have an AVF or AVG.

OBJECTIVES

The goal of this study was to evaluate whether time to thrombectomy increases the risk for loss of dialysis access and subsequent placement of a dialysis catheter at hospital discharge, at 6 months, 12 months, and data at any time after discharge.

METHODS

Using retrospective data, 444 patients were identified as having undergone thrombectomy for dialysis access dysfunction between January 2008 and April 2015, with 122 hospital admissions primarily for thrombectomy.

RESULTS

The mean age was 60.4 years, 65% were male, and 44.3% had an arteriovenous fistula as their dialysis access. The mean time to thrombectomy was 10.8 hours, and 14 patients utilised a catheter for haemodialysis as primary access upon discharge. After adjustment for prior access intervention, access type, and time to thrombectomy, the adjusted odds ratios (AOR) of a one-day delay in thrombectomy was associated with a twofold increase in requirement for catheter at discharge and at 6 months. This association remained present at any time after discharge.

CONCLUSION

In this study of patients cared for within an academic health system, a single day delay in thrombectomy nearly doubled the risk of needing a dialysis catheter at hospital discharge, 6 months, or any time after discharge.

Urinary Biomarkers of Tubular Damage Are Associated with Mortality but Not Cardiovascular Risk among Systolic Blood Pressure Intervention Trial Participants with Chronic Kidney Disease

BACKGROUND

Kidney tubulointerstitial fibrosis on biopsy is a strong predictor of chronic kidney disease (CKD) progression, and CKD is associated with elevated risk of cardiovascular disease (CVD). Tubular health is poorly quantified by traditional kidney function measures, including estimated glomerular filtration rate (eGFR) and albuminuria. We hypothesized that urinary biomarkers of tubular injury, inflammation, and repair would be associated with higher risk of CVD and mortality in persons with CKD.

METHODS

We measured urinary concentrations of interleukin-18 (IL-18), kidney injury molecule-1, neutrophil gelatinase-associated lipocalin, monocyte chemoattractant protein-1, and chitinase-3-like protein-1 (YKL-40) at baseline among 2,377 participants of the Systolic Blood Pressure Intervention Trial who had an eGFR < 60 mL/min/1.73 m2. We used Cox proportional hazards models to evaluate biomarker associations with CVD events and all-cause mortality.

RESULTS

At baseline, the mean age of participants was 72 ± 9 years, and eGFR was 48 ± 11 mL/min/1.73 m2. Over a median follow-up of 3.8 years, 305 CVD events (3.6% per year) and 233 all-cause deaths (2.6% per year) occurred. After multivariable adjustment including eGFR, albuminuria, and urinary creatinine, none of the biomarkers showed statistically significant associations with CVD risk. Urinary IL-18 (hazard ratio [HR] per 2-fold higher value, 1.14; 95% CI 1.01-1.29) and YKL-40 (HR per 2-fold higher value, 1.08; 95% CI 1.02-1.14) concentrations were each incrementally associated with higher mortality risk. Associations were similar when stratified by randomized blood pressure arm.

CONCLUSIONS

Among hypertensive trial participants with CKD, higher urinary IL-18 and YKL-40 were associated with higher risk of mortality, but not CVD.

Kidney Damage Biomarkers and Incident Chronic Kidney Disease During Blood Pressure Reduction: A Case-Control Study

BACKGROUND

Whether the increased incidence of chronic kidney disease (CKD) during intensive systolic blood pressure (SBP) lowering is accompanied by intrinsic kidney injury is unknown.

OBJECTIVE

To compare changes in kidney damage biomarkers between incident CKD case participants and matched control participants as well as between case participants in the intensive (<120 mm Hg) versus the standard (<140 mm Hg) SBP management groups of SPRINT (Systolic Blood Pressure Intervention Trial).

DESIGN

Nested case-control study within SPRINT.

SETTING

Adults with hypertension without baseline kidney disease.

PARTICIPANTS

Case participants (n = 162), who developed incident CKD during trial follow-up (128 in the intensive and 34 in the standard group), and control participants (n = 162) without incident CKD, who were matched on age, sex, race, baseline estimated glomerular filtration rate, and randomization group.

MEASUREMENTS

9 urinary biomarkers of kidney damage were measured at baseline and at 1 year. Linear mixed-effects models were used to estimate 1-year biomarker changes.

RESULTS

Higher concentrations of urinary albumin, kidney injury molecule-1, and monocyte chemoattractant protein-1 at baseline were significantly associated with greater odds of incident CKD (adjusted odds ratio per doubling: 1.50 [95% CI, 1.14 to 1.98], 1.51 [CI, 1.05 to 2.17], and 1.70 [CI, 1.13 to 2.56], respectively). After 1 year of blood pressure intervention, incident CKD case participants in the intensive group had significantly greater decreases in albumin-creatinine ratio (ACR), interleukin-18, anti-chitinase-3-like protein 1 (YKL-40), and uromodulin than the matched control participants. Compared with case participants in the standard group, those in the intensive group had significantly greater decreases in ACR, β2-microglobulin, α1-microglobulin, YKL-40, and uromodulin.

LIMITATION

Biomarker measurements were available only at baseline and 1 year.

CONCLUSION

Incident CKD in the setting of intensive SBP lowering was accompanied by decreases, rather than elevations, in levels of kidney damage biomarkers and thus may reflect benign changes in renal blood flow rather than intrinsic injury.

PRIMARY FUNDING SOURCE

National Institute for Diabetes and Digestive and Kidney Diseases.

Pulse wave velocity and central aortic pressure in systolic blood pressure intervention trial participants

Arterial stiffness, typically assessed as the aortic pulse wave velocity (PWV), and central blood pressure levels may be indicators of cardiovascular disease (CVD) risk. This ancillary study to the Systolic Blood Pressure Intervention Trial (SPRINT) obtained baseline assessments (at randomization) of PWV and central systolic blood pressure (C-SBP) to: 1) characterize these vascular measurements in the SPRINT cohort, and 2) test the hypotheses that PWV and C-SBP are associated with glucose homeostasis and markers of chronic kidney disease (CKD). The SphygmoCor^® CPV device was used to assess carotid-femoral PWV and its pulse wave analysis study protocol was used to obtain C-SBP. Valid results were obtained from 652 participants. Mean (±SD) PWV and C-SBP for the SPRINT cohort were 10.7 ± 2.7 m/s and 132.0 ± 17.9 mm Hg respectively. Linear regression analyses for PWV and C-SBP results adjusted for age, sex, and race/ethnicity in relation to several markers of glucose homeostasis and CKD did not identify any significant associations with the exception of a marginally statistically significant and modest association between PWV and urine albumin-to-creatinine ratio (linear regression estimate ± SE, 0.001 ± 0.0006; P-value 0.046). In a subset of SPRINT participants, PWV was significantly higher than in prior studies of normotensive persons, as expected. For older age groups in the SPRINT cohort (age > 60 years), PWV was compared with a reference population of hypertensive individuals. There were no compelling associations noted between PWV or C-SBP and markers of glucose homeostasis or CKD.

Clinical Trial Registration: NCT01206062.

Race, Ethnicity, and End-of-Life Care in Dialysis Patients in the United States

BACKGROUND

End-of-life care is a prominent consideration in patients on maintenance dialysis, especially when death appears imminent and quality of life is poor. To date, examination of race- and ethnicity-associated disparities in end-of-life care for patients with ESRD has largely been restricted to comparisons of white and black patients.

METHODS

We performed a retrospective national study using United States Renal Data System files to determine whether end-of-life care in United States patients on dialysis is subject to racial or ethnic disparity. The primary outcome was a composite of discontinuation of dialysis and death in a nonhospital or hospice setting.

RESULTS

Among 1,098,384 patients on dialysis dying between 2000 and 2014, the primary outcome was less likely in patients from any minority group compared with the non-Hispanic white population (10.9% versus 22.6%, P<0.001, respectively). We also observed similar significant disparities between any minority group and non-Hispanic whites for dialysis discontinuation (16.7% versus 31.2%), as well as hospice (10.3% versus 18.1%) and nonhospital death (34.4% versus 46.4%). After extensive covariate adjustment, the primary outcome was less likely in the combined minority group than in the non-Hispanic white population (adjusted odds ratio, 0.55; 95% confidence interval, 0.55 to 0.56; P<0.001). Individual minority groups (non-Hispanic Asian, non-Hispanic black, non-Hispanic Native American, and Hispanic) were significantly less likely than non-Hispanic whites to experience the primary outcome. This disparity was especially pronounced for non-Hispanic Native American and Hispanic subgroups.

CONCLUSIONS

There appear to be substantial race- and ethnicity-based disparities in end-of-life care practices for United States patients receiving dialysis.

Blood pressure and the risk of chronic kidney disease progression using multistate marginal structural models in the CRIC Study

In patients with chronic kidney disease (CKD), clinical interest often centers on determining treatments and exposures that are causally related to renal progression. Analyses of longitudinal clinical data in this population are often complicated by clinical competing events, such as end-stage renal disease (ESRD) and death, and time-dependent confounding, where patient factors that are predictive of later exposures and outcomes are affected by past exposures. We developed multistate marginal structural models (MS-MSMs) to assess the effect of time-varying systolic blood pressure on disease progression in subjects with CKD. The multistate nature of the model allows us to jointly model disease progression characterized by changes in the estimated glomerular filtration rate (eGFR), the onset of ESRD, and death, and thereby avoid unnatural assumptions of death and ESRD as noninformative censoring events for subsequent changes in eGFR. We model the causal effect of systolic blood pressure on the probability of transitioning into 1 of 6 disease states given the current state. We use inverse probability weights with stabilization to account for potential time-varying confounders, including past eGFR, total protein, serum creatinine, and hemoglobin. We apply the model to data from the Chronic Renal Insufficiency Cohort Study, a multisite observational study of patients with CKD.

Advances in understanding the renin-angiotensin-aldosterone system (RAAS) in blood pressure control and recent pivotal trials of RAAS blockade in heart failure and diabetic nephropathy

The renin-angiotensin-aldosterone system (RAAS) plays a fundamental role in the physiology of blood pressure control and the pathophysiology of hypertension (HTN) with effects on vascular tone, sodium retention, oxidative stress, fibrosis, sympathetic tone, and inflammation. Fortunately, RAAS blocking agents have been available to treat HTN since the 1970s and newer medications are being developed. In this review, we will (1) examine new anti-hypertensive medications affecting the RAAS, (2) evaluate recent studies that help provide a better understanding of which patients may be more likely to benefit from RAAS blockade, and (3) review three recent pivotal randomized trials that involve newer RAAS blocking agents and inform clinical practice.

Serum Bicarbonate and Structural and Functional Cardiac Abnormalities in Chronic Kidney Disease - A Report from the Chronic Renal Insufficiency Cohort Study

BACKGROUND

Heart failure (HF) is a frequent occurrence in chronic kidney disease (CKD) patients and predicts poor survival. Serum bicarbonate is associated with increased rates of HF in CKD; however, the mechanisms leading to this association are incompletely understood. This study aims to assess whether serum bicarbonate is independently associated with structural and functional cardiac abnormalities in CKD.

METHODS

The association between serum bicarbonate and left ventricular (LV) hypertrophy (LVH), LV mass indexed to height2.7, LV geometry, ejection fraction (EF) and diastolic dysfunction was assessed in 3,483 participants without NYHA class III/IV HF, enrolled in the Chronic Renal Insufficiency Cohort study.

RESULTS

The mean estimated glomerular filtration rate was 42.5 ± 17 ml/min/1.73 m2. The overall prevalence of LVH was 51.2%, with 57.8, 50.9 and 47.7% for bicarbonate categories <22, 22-26 and >26 mmol/l, respectively. Participants with low bicarbonate were more likely to have LVH and abnormal LV geometry (OR 1.32; 95% CI 1.07-1.64, and OR 1.57; 95% CI 1.14-2.16, respectively). However, the association was not statistically significant after adjustment for demographics, traditional cardiovascular risk factors, medications and kidney function (OR 1.07; 95% CI 0.66-1.72, and OR 1.27; 95% CI 0.64-2.51, respectively). No association was found between bicarbonate and systolic or diastolic dysfunction. During follow-up, no significant changes in LV mass or EF were observed in any bicarbonate strata.

CONCLUSIONS

In a large CKD study, serum bicarbonate was associated with LV mass and concentric LVH; however, this association was attenuated after adjustment for clinical factors suggesting that the observed cardiac effects are mediated through yet unknown mechanisms.

Prevalence and Prognostic Significance of Apparent Treatment Resistant Hypertension in Chronic Kidney Disease: Report From the Chronic Renal Insufficiency Cohort Study

The association between apparent treatment resistant hypertension (ATRH) and clinical outcomes is not well studied in chronic kidney disease. We analyzed data on 3367 hypertensive participants in the Chronic Renal Insufficiency Cohort (CRIC) to determine prevalence, associations, and clinical outcomes of ATRH in nondialysis chronic kidney disease patients. ATRH was defined as blood pressure ≥140/90 mm Hg on ≥3 antihypertensives, or use of ≥4 antihypertensives with blood pressure at goal at baseline visit. Prevalence of ATRH was 40.4%. Older age, male sex, black race, diabetes mellitus, and higher body mass index were independently associated with higher odds of having ATRH. Participants with ATRH had a higher risk of clinical events than participants without ATRH-composite of myocardial infarction, stroke, peripheral arterial disease, congestive heart failure (CHF), and all-cause mortality (hazard ratio [95% confidence interval], 1.38 [1.22-1.56]); renal events (1.28 [1.11-1.46]); CHF (1.66 [1.38-2.00]); and all-cause mortality (1.24 [1.06-1.45]). The subset of participants with ATRH and blood pressure at goal on ≥4 medications also had higher risk for composite of myocardial infarction, stroke, peripheral arterial disease, CHF, and all-cause mortality (hazard ratio [95% confidence interval], (1.30 [1.12-1.51]) and CHF (1.59 [1.28-1.99]) than those without ATRH. ATRH was associated with significantly higher risk for CHF and renal events only among those with estimated glomerular filtration rate ≥30 mL/min per 1.73 m(2). Our findings show that ATRH is common and associated with high risk of adverse outcomes in a cohort of patients with chronic kidney disease. This underscores the need for early identification and management of patients with ATRH and chronic kidney disease.

Kidney Disease among Patients with Sickle Cell Disease, Hemoglobin SS and SC

BACKGROUND AND OBJECTIVES

Sickle cell disease (SCD) is an inherited anemia that afflicts millions worldwide. Kidney disease is a major contributor to its morbidity and mortality. We examined contemporary and historical SCD populations to understand how renal disease behaved in hemoglobin SS (HbSS) compared with HbSC.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

Kidney function was examined in the multicentered Treatment of Pulmonary Hypertension and Sickle Cell Disease with Sildenafil Therapy (Walk-PHaSST) Trial (HbSS=463; HbSC=127; years 2007-2009) and historical comparator populations from the Cooperative Study of Sickle Cell Disease (CSSCD; HbSS=708) and the Multicenter Study of Hydroxyurea in Sickle Cell Disease (MSH; HbSS=299).

RESULTS

In adults with SCD, eGFR was lower among older individuals: -1.78 ml/min per 1.73 m(2) per year of age (95% confidence interval [95% CI], -2.06 to -1.50; Walk-PHaSST Trial), -1.75 ml/min per 1.73 m(2) per year of age (95% CI, -2.05 to -1.44; MSH), and -1.69 ml/min per 1.73 m(2) per year of age (95% CI, -2.00 to -1.38; CSSCD) in HbSS compared with -1.09 ml/min per 1.73 m(2) per year of age (95% CI, -1.39 to -0.75) in HbSC (Walk-PHaSST Trial). Macroalbuminuria was seen in 20% of participants with SCD (HbSS or HbSC; P=0.45; Walk-PHaSST Trial), but microalbuminuria was more prevalent in HbSS (44% versus 23% in HbSC; P<0.002). In the Walk-PHaSST Trial, albuminuria was associated with hemolysis (higher lactate dehydrogenase, P<0.001; higher absolute reticulocyte count, P<0.02; and lower Hb, P=0.07) and elevated systolic BP (P<0.001) in HbSS. One half of all participants with HbSS (20 of 39) versus one fifth without (41 of 228) elevated tricuspid regurgitant jet velocity (≥3 m/s; adverse prognostic indicator in SCD) had macroalbuminuria (P<0.001). In the CSSCD, overt proteinuria, detected (less sensitively) by urine dipstick, associated with higher 3-year mortality (odds ratio, 2.48; 95% CI, 1.07 to 5.77). Serum bicarbonate was lower in HbSS (23.8 versus 24.8 mEq/dl in HbSC; P<0.05) and associated with reticulocytopenic anemia and decreased renal function.

CONCLUSIONS

In SCD, albuminuria or proteinuria was highly prevalent, in HbSS more than in HbSC. Proteinuria associated with mortality in HbSS. Older individuals had a lower than expected eGFR, and this was more prominent in HbSS. Current management does not routinely address renal complications in SCD, which could plausibly reduce morbidity and mortality.

Development and Implementation of Team-Based Panel Management Tools: Filling the Gap between Patient and Population Information Systems

Effective team-based models of care, such as the Patient-Centered Medical Home, require electronic tools to support proactive population management strategies that emphasize care coordination and quality improvement. Despite the spread of electronic health records (EHRs) and vendors marketing population health tools, clinical practices still may lack the ability to have: (1) local control over types of data collected/reports generated, (2) timely data (eg, up-to-date data, not several months old), and accordingly (3) the ability to efficiently monitor and improve patient outcomes. This article describes a quality improvement project at the hospital system level to develop and implement a flexible panel management (PM) tool to improve care of subpopulations of patients (eg, panels of patients with diabetes) by clinical teams. An in-depth case analysis approach is used to explore barriers and facilitators in building a PM registry tool for team-based management needs using standard data elements (eg, laboratory values, pharmacy records) found in EHRs. Also described are factors that may contribute to sustainability; to date the tool has been adapted to 6 disease-focused subpopulations encompassing more than 200,000 patients. Two key lessons emerged from this initiative: (1) though challenging, team-based clinical end users and information technology needed to work together consistently to refine the product, and (2) locally developed population management tools can provide efficient data tracking for frontline clinical teams and leadership. The preliminary work identified critical gaps that were successfully addressed by building local PM registry tools from EHR-derived data and offers lessons learned for others engaged in similar work. (Population Health Management 2016;19:232-239).

Chronic kidney disease

This issue provides a clinical overview of chronic kidney disease, focusing on prevention, diagnosis, treatment, and patient information. The content of In the Clinic is drawn from the clinical information and education resources of the American College of Physicians (ACP), including ACP Smart Medicine and MKSAP (Medical Knowledge and Self-Assessment Program). Annals of Internal Medicine editors develop In the Clinic from these primary sources in collaboration with the ACP's Medical Education and Publishing divisions and with the assistance of science writers and physician writers. Editorial consultants from ACP Smart Medicine and MKSAP provide expert review of the content. Readers who are interested in these primary resources for more detail can consult http://smartmedicine.acponline.org, http://mksap.acponline.org, and other resources referenced in each issue of In the Clinic.

Outbreak of Fluoroquinolone-Resistant Escherichia coli Infections after Transrectal Ultrasound—Guided Biopsy of the Prostate

Design.

We conducted an investigation after identifying a cluster of 4 serious infections following transrectal ultrasound–guided biopsy of the prostate (TRUBP) during a 2-month period.

Setting.

veterans Affairs medical center.

Patients.

Patients with urinary tract infection (UTI) after TRUBP and time-matched controls with no evidence of infection.

Methods.

The incidence of UTI within 30 days after TRUBP was calculated from 2002 through 2010. We evaluated the correlation between infection with fluoroquinolone-resistant gram-negative bacilli (GNB) and fluoroquinolone resistance in outpatient Escherichia coli urinary isolates and performed a case-control study to determine risk factors for infection with fluoroquinolone-resistant GNB. Processes for TRUBP prophylaxis, procedures, and equipment sterilization were reviewed.

Results.

An outbreak of UTI due to fluoroquinolone-resistant E. coli after TRUBP began 2 years before the cluster was identified and was correlated with increasing fluoroquinolone resistance in outpatient E. coli. No deficiencies were identified in equipment processing or biopsy procedures. Fluoroquinolone-resistant E. coli UTI after TRUBP was independently associated with prior infection with fluoroquinolone-resistant GNB (adjusted odds ratio, 20.8; P = .005). A prediction rule including prior UTI, hospitalization in the past year, and previous infection with fluoroquinolone-resistant GNB identified only 17 (49%) of 35 cases.

Conclusions.

The outbreak of fluoroquinolone-resistant E. coli infections after TRUBP closely paralleled rising rates of fluoroquinolone resistance among outpatient E. coli isolates. The delayed detection of the outbreak and the absence of sensitive predictors of infection suggest that active surveillance for infection after TRUBP is necessary in the context of increasing fluoroquinolone resistance in the United States.

Risk factors for acute gastrointestinal bleeding following myocardial infarction in veteran patients who are prescribed clopidogrel

OBJECTIVE

Our aim was to identify risk factors for acute gastrointestinal (GI) bleeding in patients with myocardial infarction (MI) who were prescribed clopidogrel following hospital discharge.

METHODS

Data were collected retrospectively from patients treated in Veteran Affairs hospitals in Ohio, USA, from 2001 to 2008 with a primary diagnosis of MI (International Classification of Diseases, 9th Revision) and a prescription for clopidogrel filled within 48 h of discharge. Primary outcome was acute GI bleeding after discharge.

RESULTS

Acute GI bleeding occurred in 107 of 3218 patients. Bleeding occurred in those who were elder (66.2 vs. 62.4 years, P = 0.0002), had lower glomerular filtration rate (74 vs. 81 mL/min, P = 0.024), had filled prescription for warfarin (15.9% vs. 6.9%, P = 0.0004), diagnosed as atrial fibrillation (20.6% vs. 11.1%, P = 0.003), chronic liver (5.6% vs. 2.2%, P = 0.018) or kidney disease (29.0% vs. 19.4%, P = 0.016). A risk model and GI bleed risk score were developed and showed that patients with age >65 years, use of warfarin, the presence of chronic liver or kidney disease were at increased risk for GI bleeding.

CONCLUSIONS

Veterans patients of advanced age, using warfarin and with chronic liver and kidney disease may be at increased risk of GI bleeding when prescribed clopidogrel following MI. A scoring system may help to identify patients at high risk for GI bleeding.

Association of serum bicarbonate with risk of renal and cardiovascular outcomes in CKD: a report from the Chronic Renal Insufficiency Cohort (CRIC) study

BACKGROUND

The purpose of this study is to evaluate serum bicarbonate level as a risk factor for renal outcomes, cardiovascular events, and mortality in patients with chronic kidney disease (CKD).

STUDY DESIGN

Observational cohort study.

SETTING & PARTICIPANTS

3,939 participants with CKD stages 2-4 who enrolled in the Chronic Renal Insufficiency Cohort (CRIC) between June 2003 and December 2008.

PREDICTOR

Serum bicarbonate level.

OUTCOMES

Renal outcomes, defined as end-stage renal disease (either initiation of dialysis therapy or kidney transplantation) or 50% reduction in estimated glomerular filtration rate (eGFR); atherosclerotic events (myocardial infarction, stroke, or peripheral arterial disease); congestive heart failure events; and death.

MEASUREMENTS

Time to event.

RESULTS

Mean eGFR was 44.8 ± 16.8 (SD) mL/min/1.73 m(2), and median serum bicarbonate level was 24 (IQR, 22-26) mEq/L. During a median follow-up of 3.9 years, 374 participants died, 767 had a renal outcome, 332 experienced an atherosclerotic event, and 391 had a congestive heart failure event. In adjusted analyses, the risk of developing a renal end point was 3% lower per 1-mEq/L increase in serum bicarbonate level (HR, 0.97; 95% CI, 0.94-0.99; P = 0.01). The association was stronger for participants with eGFR >45 mL/min/1.73 m(2) (HR, 0.91; 95% CI, 0.85-0.97; P = 0.004). The risk of heart failure increased by 14% (HR, 1.14; 95% CI, 1.03-1.26; P = 0.02) per 1-mEq/L increase in serum bicarbonate level over 24 mEq/L. Serum bicarbonate level was not associated independently with atherosclerotic events (HR, 0.99; 95% CI, 0.95-1.03; P = 0.6) and all-cause mortality (HR, 0.98; 95% CI, 0.95-1.02; P = 0.3).

LIMITATIONS

Single measurement of sodium bicarbonate.

CONCLUSIONS

In a cohort of participants with CKD, low serum bicarbonate level was an independent risk factor for kidney disease progression, particularly for participants with preserved kidney function. The risk of heart failure was higher at the upper extreme of serum bicarbonate levels. There was no association between serum bicarbonate level and all-cause mortality or atherosclerotic events.