Apparent Treatment-Resistant Hypertension Assessed by Office and Ambulatory Blood Pressure in Chronic Kidney Disease-A Report from the Chronic Renal Insufficiency Cohort Study

Background

Apparent treatment-resistant hypertension is common in patients with CKD. Whether measurement of 24-hour ambulatory BP monitoring is valuable for risk-stratifying patients with resistant hypertension and CKD is unclear.

Methods

We analyzed data from the Chronic Renal Insufficiency Cohort study, a prospective study of participants (n=1186) with CKD. Office BP was measured using standardized protocols; ambulatory BP was measured using Spacelabs monitors. Apparent treatment-resistant hypertension was defined on the basis of office BP, ambulatory BP monitoring, and use of more than three antihypertensive medications. Outcomes were composite cardiovascular disease, kidney outcomes, and mortality. Groups were compared using Cox regression analyses with a control group of participants without apparent treatment-resistant hypertension.

Results

Of 475 participants with apparent treatment-resistant hypertension on the basis of office BP, 91.6% had apparent treatment-resistant hypertension confirmed by ambulatory BP monitoring. Unadjusted event rates of composite cardiovascular disease, kidney outcomes, and mortality were higher in participants with ambulatory BP monitoring-defined apparent treatment-resistant hypertension compared with participants without apparent treatment-resistant hypertension. In adjusted analyses, the risks of composite cardiovascular disease (hazard ratio, 1.27; 95% confidence interval [95% CI], 0.59 to 2.7), kidney outcomes (hazard ratio, 1.68; 95% CI, 0.88 to 3.21), and mortality (hazard ratio, 1.27; 95% CI, 0.5 to 3.25) were not statistically significantly higher in participants with ambulatory BP monitoring-defined apparent treatment-resistant hypertension compared with participants without apparent treatment-resistant hypertension.

Conclusions

In our study population with CKD, most patients with apparent treatment-resistant hypertension defined on the basis of office BP have apparent treatment-resistant hypertension confirmed by ambulatory BP monitoring. Although ABPM-defined apparent treatment-resistant hypertension was not independently associated with clinical outcomes, it identified participants at high risk for adverse clinical outcomes.

Lipidomic Signature of Progression of Chronic Kidney Disease in the Chronic Renal Insufficiency Cohort

Introduction

Human studies report conflicting results on the predictive power of serum lipids on the progression of chronic kidney disease. We aimed to systematically identify the lipids that predict progression to end-stage kidney disease.

Methods

From the Chronic Renal Insufficiency Cohort, 79 patients with chronic kidney disease stages 2 to 3 who progressed to end-stage kidney disease over 6 years of follow-up were selected and frequency matched by age, sex, race, and diabetes with 121 nonprogressors with less than 25% decline in estimated glomerular filtration rate during the follow-up. The patients were randomly divided into training and test sets. We applied liquid chromatography-mass spectrometry-based lipidomics on visit year 1 samples.

Results

We identified 510 lipids, of which the top 10 coincided with false discovery threshold of 0.058 in the training set. From the top 10 lipids, the abundance of diacylglycerols and cholesteryl esters was lower, but that of phosphatidic acid 44:4 and monoacylglycerol 16:0 was significantly higher in progressors. Using logistic regression models, a multimarker panel consisting of diacylglycerols and monoacylglycerol independently predicted progression. The c-statistic of the multimarker panel added to the base model consisting of estimated glomerular filtration rate and urine protein-to-creatinine ratio as compared with that of the base model was 0.92 (95% confidence interval: 0.88–0.97) and 0.83 (95% confidence interval: 0.76–0.90, P < 0.01), respectively, an observation that was validated in the test subset.

Discussion

We conclude that a distinct panel of lipids may improve prediction of progression of chronic kidney disease beyond estimated glomerular filtration rate and urine protein-to-creatinine ratio when added to the base model.

Masked Hypertension and Elevated Nighttime Blood Pressure in CKD: Prevalence and Association with Target Organ Damage

BACKGROUND AND OBJECTIVES

Masked hypertension and elevated nighttime BP are associated with increased risk of hypertensive target organ damage and adverse cardiovascular and renal outcomes in patients with normal kidney function. The significance of masked hypertension for these risks in patients with CKD is less well defined. The objective of this study was to evaluate the association between masked hypertension and kidney function and markers of cardiovascular target organ damage, and to determine whether this relationship was consistent among those with and without elevated nighttime BP.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

This was a cross-sectional study. We performed 24-hour ambulatory BP in 1492 men and women with CKD enrolled in the Chronic Renal Insufficiency Cohort Study. We categorized participants into controlled BP, white-coat, masked, and sustained hypertension on the basis of clinic and 24-hour ambulatory BP. We obtained echocardiograms and measured pulse wave velocity in 1278 and 1394 participants, respectively.

RESULTS

The percentages of participants with controlled BP, white-coat, masked, and sustained hypertension were 49.3%, 4.1%, 27.8%, and 18.8%, respectively. Compared with controlled BP, masked hypertension independently associated with low eGFR (-3.2 ml/min per 1.73 m(2); 95% confidence interval, -5.5 to -0.9), higher proteinuria (+0.9 unit higher in log2 urine protein; 95% confidence interval, 0.7 to 1.1), and higher left ventricular mass index (+2.52 g/m(2.7); 95% confidence interval, 0.9 to 4.1), and pulse wave velocity (+0.92 m/s; 95% confidence interval, 0.5 to 1.3). Participants with masked hypertension had lower eGFR only in the presence of elevated nighttime BP (-3.6 ml/min per 1.73 m(2); 95% confidence interval, -6.1 to -1.1; versus -1.4 ml/min per 1.73 m(2); 95% confidence interval, -6.9 to 4.0, among those with nighttime BP <120/70 mmHg; P value for interaction with nighttime systolic BP 0.002).

CONCLUSIONS

Masked hypertension is common in patients with CKD and associated with lower eGFR, proteinuria, and cardiovascular target organ damage. In patients with CKD, ambulatory BP characterizes the relationship between BP and target organ damage better than BP measured in the clinic alone.

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.

Prevalence, Predictors, and Outcomes of Pulmonary Hypertension in CKD

Pulmonary hypertension (PH) is associated with poor outcomes in the dialysis and general populations, but its effect in CKD is unclear. We evaluated the prevalence and predictors of PH measures and their associations with long-term clinical outcomes in patients with nondialysis-dependent CKD. Chronic Renal Insufficiency Cohort (CRIC) Study participants who had Doppler echocardiography performed were considered for inclusion. PH was defined as the presence of estimated pulmonary artery systolic pressure (PASP) >35 mmHg and/or tricuspid regurgitant velocity (TRV) >2.5 m/s. Associations between PH, PASP, and TRV and cardiovascular events, renal events, and all-cause mortality were examined using Cox proportional hazards models. Of 2959 eligible participants, 21% (n=625) had PH, with higher rates among those with lower levels of kidney function. In the multivariate model, older age, anemia, lower left ventricular ejection fraction, and presence of left ventricular hypertrophy were associated with greater odds of having PH. After adjusting for relevant confounding variables, PH was independently associated with higher risk for death (hazard ratio, 1.38; 95% confidence interval, 1.10 to 1.72) and cardiovascular events (hazard ratio, 1.23; 95% confidence interval, 1.00 to 1.52) but not renal events. Similarly, TRV and PASP were associated with death and cardiovascular events but not renal events. In this study of patients with CKD and preserved left ventricular systolic function, we report a high prevalence of PH. PH and higher TRV and PASP (echocardiographic measures of PH) are associated with adverse outcomes in CKD. Future studies may explain the mechanisms that underlie these findings.

Recruitment of Hispanics into an observational study of chronic kidney disease: the Hispanic Chronic Renal Insufficiency Cohort Study experience

Despite the large burden of chronic kidney disease (CKD) in Hispanics, this population has been underrepresented in research studies. We describe the recruitment strategies employed by the Hispanic Chronic Renal Insufficiency Cohort Study, which led to the successful enrollment of a large population of Hispanic adults with CKD into a prospective observational cohort study. Recruitment efforts by bilingual staff focused on community clinics with Hispanic providers in high-density Hispanic neighborhoods in Chicago, academic medical centers, and private nephrology practices. Methods of publicizing the study included church meetings, local Hispanic print media, Spanish television and radio stations, and local health fairs. From October 2005 to July 2008, we recruited 327 Hispanics aged 21-74 years with mild-to-moderate CKD as determined by age-specific estimated glomerular filtration rate (eGFR). Of 716 individuals completing a screening visit, 49% did not meet eGFR inclusion criteria and 46% completed a baseline visit. The mean age at enrollment was 57.1 and 67.1% of participants were male. Approximately 75% of enrolled individuals were Mexican American, 15% Puerto Rican, and 10% had other Latin American ancestry. Eighty two percent of participants were Spanish-speakers. Community-based and academic primary care clinics yielded the highest percentage of participants screened (45.9% and 22.4%) and enrolled (38.2% and 24.5%). However, academic and community-based specialty clinics achieved the highest enrollment yield from individuals screened (61.9% to 71.4%). A strategy focused on primary care and nephrology clinics and the use of bilingual recruiters allowed us to overcome barriers to the recruitment of Hispanics with CKD.

Relaxin decreases renal interstitial fibrosis and slows progression of renal disease

BACKGROUND

Relaxin, a hormone of the insulin-growth factor family, promotes collagen remodeling. In rodent models of pulmonary and dermal fibrosis, relaxin reduced interstitial fibrosis. To study relaxin's effect in renal disease, we used the experimental bromoethylamine (BEA) model that leads to severe renal interstitial fibrosis, a decrease in glomerular filtration rate, and albuminuria at one month.

METHODS

Rats were injected with BEA one week prior to implantation of an osmotic pump delivering relaxin (2 microg/hour) or vehicle continuously for 28 days.

RESULTS

BEA caused a significant decrease in creatinine clearance, which was partially prevented by relaxin. In the relaxin-treated BEA rats, serum creatinine was normal, and albumin excretion was slightly decreased. By morphometric measurement, relaxin administration was associated with a significant decrease in interstitial fibrosis at the corticomedullary junction. This was accompanied by a decrease in the number of ED-1 positive cells (an index of macrophage infiltration) and in the intensity of immunohistochemical staining for transforming growth factor-beta. This antifibrotic effect of relaxin did not appear to be mediated by systemic hemodynamic changes since the mean arterial pressure was not significantly different among the groups.

CONCLUSIONS

Relaxin may have a useful application in decreasing interstitial fibrosis and thereby slowing the progression of renal disease.

Cardiovascular Effects of Cocaine: Focus on Hypertension

Cocaine, a naturally occurring alkaloid, has increasingly been implicated in a myriad of medical complications. The majority of these relate to cardiovascular effects of the drug, a potent sympathomimetic. In addition, cocaine has effects on endothelin-1, the sodium channel, and nitric oxide which further enhance its untoward cardiovascular effects. The cardiovascular effects of cocaine include myocardial ischemia or infarction, ventricular arrhythmias and sudden death, cardiomyopathy, cerebral infarction or hemorrhage, and acute hypertension. Although hypertension has been described in the offspring of cocaine using mothers, two recent studies have not found an increased prevalence of chronic hypertension in adults. Nonetheless, long term abuse of cocaine can lead to the various forms of target organ damage usually associated with untreated essential hypertension, presumably due to frequent intermittent and severe elevations in blood pressure. (c)1999 by Le Jacq Communications, Inc.

Prevalence of hypertension in chronic cocaine users

The association of cocaine and acute hypertension is well known; however, cocaine use has not generally been linked to chronic hypertension. We hypothesized that chronic use of cocaine over time would increase the prevalence of hypertension and that cocaine induced vasoconstriction would result in urine protein leakage, manifested by microalbuminuria. Therefore, we studied a population of predominantly black male patients admitted for addiction treatment whose drug of dependence was cocaine. A urine toxicology screen was considered positive if cocaine was detected within 24 h prior to or during admission to the hospital. A total of 301 patients with normal renal function were observed over their 2 week hospitalization. The majority (62%) of the patients were normotensive regardless of the status of their initial urine toxicology screen. Twenty percent of the population had acutely elevated blood pressure that normalized within 1 day, whereas 18% had blood pressure chronically >140/90 mm Hg (chronic hypertension). Levels of systolic and diastolic blood pressures were examined at age deciles and compared to the NHANES III (Third National Health and Nutrition Examination Survey) data for a predominantly black population. There was no significant difference in blood pressure with age in the cocaine users compared to the NHANES groups. Random urine samples were screened for the presence of microalbuminuria and no significant elevation was detected in any of the samples tested. We conclude that chronic cocaine use is associated with acute but not chronic hypertension in middle-aged black males. Cocaine use does not cause microalbuminuria.