Sex difference in cardiovascular risk in patients with chronic kidney disease: pooled analysis of four cohort studies.

BACKGROUND: Progression of chronic kidney disease (CKD) has proven to be faster in men than in women. Whether the same holds true for cardiovascular risk remains ill-defined. METHODS: We conducted a pooled analysis of 4 cohort studies from 40 nephrology clinics in Italy including patients with CKD (estimated GFR<60 ml/min/1.73m2 or higher if proteinuria > 0.15 g/day). The aim was to compare multivariable-adjusted risk (Hazard Ratio, 95% Confidence Interval) of a composite cardiovascular endpoint (cardiovascular death and non-fatal myocardial infarction, congestive heart failure, stroke, revascularization, peripheral vascular disease, and non-traumatic amputation) in women (n = 1 192) versus men (n = 1 635). RESULTS: At baseline, women had slightly higher systolic blood pressure (SBP) as compared with men (139±19 vs 138±18 mmHg, P = 0.049), lower eGFR (33.4 vs 35.7 mL/min/1.73 m2, P = 0.001) and lower urine protein excretion (0.30 g/day vs 0.45 g/day in men, P < 0.001). Women did not differ from men in age and prevalence of diabetes while having a lower prevalence of cardiovascular disease, left ventricular hypertrophy and smoking habit. During a median follow-up of 4.0 years, 517 fatal and non-fatal cardiovascular events were registered (199 in women and 318 in men). The adjusted risk of cardiovascular events was lower in women (0.73, 0.60-0.89, P = 0.002) than in men; however, the cardiovascular risk advantage of women progressively diminished as SBP (as continuous variable) increased (P for interaction = 0.021). Similar results were obtained when considering SBP categories; when compared to men, women had lower cardiovascular risk for SBP <130 mmHg (0.50, 0.31-0.80; P = 0.004) and between 130-140 mmHg (0.72, 0.53-0.99; P = 0.038), while no difference was observed for SBP>140 mmHg (0.85, 0.64-1.11; P = 0.232). CONCLUSIONS: Higher BP levels abolish the cardiovascular protection seen in female vs male patients with overt CKD. This finding supports the need for higher awareness of hypertensive burden in women with CKD.

Dipping Status, Ambulatory Blood Pressure Control, Cardiovascular Disease, and Kidney Disease Progression: A Multicenter Cohort Study of CKD.

RATIONALE & OBJECTIVE: Ambulatory blood pressure (BP) monitoring allows concurrent evaluation of BP control and nocturnal BP dipping status, both related to adverse outcomes. However, few studies have assessed the prognostic role of combining information on dipping status and achieved ambulatory BP in patients with chronic kidney disease (CKD). STUDY DESIGN: Prospective observational cohort study. SETTING & PARTICIPANTS: 906 patients with hypertension and CKD attending 1 of 3 Italian nephrology clinics. EXPOSURE: Four groups were defined by simultaneously classifying systolic ambulatory BP levels as being at goal (daytime SBP <135 and nighttime SBP <120 mm Hg) or above goal, and the presence or absence of nocturnal dipping (nighttime to daytime SBP ratio of <0.9 versus ≥0.9). OUTCOME: The composite of time to initiation of maintenance dialysis or estimated glomerular filtration rate (eGFR) decline ≥50%, and the composite of fatal and nonfatal cardiovascular events. ANALYTICAL APPROACH: Multivariable Cox proportional hazards models were used to estimate risks of kidney disease progression and cardiovascular disease in the 4 exposure groups where nocturnal dipping with systolic ambulatory BP at goal was the reference group. RESULTS: The mean patient age was 63.8 years, 61% were male, and 26.4% had diabetes; eGFR was 41.1 ± 20.8 mL/min/1.73 m2. The dipping prevalence in each of the 4 groups was as follows: nocturnal dipping with ambulatory BP at goal, 18.6%; no nocturnal dipping with ambulatory BP at goal, 20.5%; nocturnal dipping with ambulatory BP above goal, 11.8%; and no nocturnal dipping with ambulatory BP above goal, 49.1%. Among patients with ambulatory BP above goal, the risk of cardiovascular events was greater in the absence (HR, 2.79 [95% CI, 1.64-4.75]) and presence (HR, 2.05 [95% CI, 1.10-3.84]) of nocturnal dipping. The same held true for risk of kidney disease progression (HRs of 2.40 [95% CI, 1.58-3.65] and 2.11 [95% CI, 1.28-3.48] in the absence and presence of nocturnal dipping, respectively). Patients at the ambulatory BP goal but who did not experience nocturnal dipping had an increased risk of the cardiovascular end point (HR, 2.06 [95% CI, 1.15-3.68]) and the kidney disease progression outcome (HR, 1.82 [95% CI, 1.17-2.82]). LIMITATIONS: Lack of a diverse cohort (all those enrolled were White). Residual uncontrolled confounding. CONCLUSIONS: Systolic ambulatory BP above goal or the absence of nocturnal dipping, regardless of ambulatory BP, is associated with higher risks of cardiovascular disease and kidney disease progression among patients with CKD. PLAIN-LANGUAGE SUMMARY: Among patients with chronic kidney disease (CKD), ambulatory blood pressure (BP) monitoring improves the identification of individuals at high risk of clinical disease outcomes. Those with uncontrolled ambulatory BP are known to have a higher risk of developing cardiovascular disease and kidney disease progression, particularly when their ambulatory BP does not decline by at least 10% at night. Whether this is also true for patients with presence of optimal ambulatory BP levels but a BP pattern of no nighttime decline is largely unknown. We measured ambulatory BP in 900 Italian patients with CKD and followed them for several years. We found that, independent of ambulatory BP level, the absence of nighttime reductions in BP was associated with worsening of CKD and more frequent cardiovascular events. The absence of nighttime declines in BP is an independent risk factor for adverse events among patients with CKD. Future studies are needed to examine whether treating the absence of nighttime declines in BP improves clinical outcomes.

Sex difference in ambulatory blood pressure control associates with risk of ESKD and death in CKD patients receiving stable nephrology care.

BACKGROUND: It is unknown whether faster progression of chronic kidney disease (CKD) in men than in women relates to differences in ambulatory blood pressure (ABP) levels. METHODS: We prospectively evaluated 906 hypertensive CKD patients (553 men) regularly followed in renal clinics to compare men versus women in terms of ABP control [daytime <135/85 and nighttime blood pressure (BP) <120/70 mmHg] and risk of all-cause mortality and end-stage kidney disease (ESKD). RESULTS: Age, estimated glomerular filtration rate and use of renin-angiotensin system inhibitors were similar in men and women, while proteinuria was lower in women [0.30 g/24 h interquartile range (IQR) 0.10-1.00 versus 0.42 g/24 h, IQR 0.10-1.28, P = 0.025]. No sex-difference was detected in office BP levels; conversely, daytime and nighttime BP were higher in men (134 ± 17/78 ± 11 and 127 ± 19/70 ± 11 mmHg) than in women (131 ± 16/75 ± 11, P = 0.005/P < 0.001 and 123 ± 20/67 ± 12, P = 0.006/P < 0.001), with ABP goal achieved more frequently in women (39.1% versus 25.1%, P < 0.001). During a median follow-up of 10.7 years, 275 patients reached ESKD (60.7% men) and 245 died (62.4% men). Risks of ESKD and mortality (hazard ratio and 95% confidence interval), adjusted for demographic and clinical variables, were higher in men (1.34, 1.02-1.76 and 1.36, 1.02-1.83, respectively). Adjustment for office BP at goal did not modify this association. In contrast, adjustment for ABP at goal attenuated the increased risk in men for ESKD (1.29, 0.98-1.70) and death (1.31, 0.98-1.77). In the fully adjusted model, ABP at goal was associated with reduced risk of ESKD (0.49, 0.34-0.70) and death (0.59, 0.43-0.80). No interaction between sex and ABP at goal on the risk of ESKD and death was found, suggesting that ABP-driven risks are consistent in males and females. CONCLUSIONS: Our study highlights that higher ABP significantly contributes to higher risks of ESKD and mortality in men.

Proteinuria and nocturnal blood pressure dipping in hypertensive children and adolescents.

BACKGROUND: The absence of nocturnal blood pressure dipping is associated with adverse cardiovascular outcomes in adults, and proteinuria is a risk factor for non-dipping in this population. Risk factors for non-dipping in children are largely unknown. METHODS: We retrospectively identified patients aged 5-19 years who underwent 24-h ambulatory blood pressure monitoring (ABPM) from August 2018 to January 2019 and had a spot urine protein-to-creatinine ratio (PCR) within 1 year of their ABPM. Dipping was defined as ≥10% reduction in systolic and diastolic blood pressure from day to night. Multivariable logistic and linear regression models evaluated the association of proteinuria with non-dipping. RESULTS: Among 77 children identified, 27 (35.1%) were non-dippers. Each two-fold higher urine PCR was associated with 38% higher odds of non-dipping, after adjusting for body mass index (BMI). Higher urine PCR was also associated with a lower diastolic dipping percentage by 1.33 (95% confidence interval 0.31-2.34), after adjusting for BMI, age, and estimated glomerular filtration rate. CONCLUSIONS: Limitations of this study include its retrospective design and the time lapse between urine PCR and ABPM. Proteinuria appears to be associated with blood pressure non-dipping in children. This finding needs to be confirmed in prospective studies. IMPACT: Our study demonstrates the association of proteinuria with non-dipping of blood pressure in children. This association has been explored in adults, but to our knowledge, this is the first time it is evaluated in children referred for evaluation of elevated blood pressure. Non-dipping is a modifiable risk factor for kidney function decline and cardiovascular disease in adulthood, and thus early identification in children is important. The association between proteinuria and non-dipping in children will allow us to more readily identify those at risk, with a future focus on interventions to modify blood pressure dipping patterns.

Nephroprotection by SGLT2 Inhibition: Back to the Future?

The introduction of sodium/glucose cotransporter 2 inhibitors (SGLT2i) has opened new perspectives for the management of diabetic population at risk of or with chronic kidney disease (CKD). More important, recent, large real-world studies have repositioned the nephroprotective efficacy of SGLT2i emerged from randomized trials within the frame of effectiveness. Furthermore, the salutary effects of these agents may extend to the nondiabetic population according to the positive results of current studies. Nevertheless, the clear benefits of these agents on the prevention of organ damage contrast with their unexpected, limited use in clinical practice. One potential barrier is the acute decline in glomerular filtration rate (GFR) commonly observed at the beginning of treatment. This phenomenon is reminiscent of the early response to the traditional nephroprotective interventions, namely blood pressure lowering, dietary protein and salt restriction and the inhibition of the renin-angiotensin system. Under this perspective, the "check-mark" sign observed in the GFR trajectory over the first weeks of SGT2i therapy should renew interest on the very basic goal of CKD treatment, i.e., alleviate hyperfiltration in viable nephrons in order to prolong their function.

Sex Differences in the Progression of CKD Among Older Patients: Pooled Analysis of 4 Cohort Studies.

RATIONALE & OBJECTIVE: Data for the association of sex with chronic kidney disease (CKD) progression are conflicting, a relationship this study sought to examine. STUDY DESIGN: Pooled analysis of 4 Italian observational cohort studies. SETTING & PARTICIPANTS: 1,311 older men and 1,024 older women with estimated glomerular filtration rate (eGFR)<45mL/min/1.73m2 followed up in renal clinics. PREDICTOR: Sex. OUTCOMES: End-stage kidney disease (ESKD), defined as maintenance dialysis or kidney transplantation, as the primary outcome; all-cause mortality and eGFR decline as secondary outcomes. ANALYTICAL APPROACH: Cox proportional hazard analysis to estimate the relative risk for ESKD and mortality and linear mixed models to estimate the rate of eGFR decline. RESULTS: Age, systolic blood pressure, and use of renin-angiotensin system inhibitors were similar in men and women. Baseline eGFRs were 27.6±10.2 in men and 26.0±10.6mL/min/1.73m2 in women (P<0.001), while median proteinuria was lower in women (protein excretion, 0.45 [IQR, 0.14-1.10] g/d) compared with men (0.69 [IQR 0.19-1.60] g/d; P<0.001). During a median follow-up of 4.2 years, 757 developed ESKD (59.4% men) and 471 died (58.4% men). The adjusted risks for ESKD and mortality were higher in men (HRs of 1.50 [95% CI, 1.28-1.77] and 1.30 [95% CI, 1.06-1.60], respectively). This finding was consistent across CKD stages. We observed a significant interaction between sex and proteinuria, with the risk for ESKD in men being significantly greater than for women at a level of proteinuria of ∼0.5g/d or greater. The slope of decline in eGFR was steeper in men (-2.09; 95% CI, -2.21 to-1.97mL/min/1.73m2 per year) than in women (-1.79; 95% CI, -1.92 to-1.66mL/min/1.73m2 per year; P<0.001). Although sex differences in eGFR decline were not different across CKD stages (P=0.3), the difference in slopes between men and women was progressively larger with proteinuria >0.5g/d (P = 0.04). LIMITATIONS: Residual confounding; only whites were included. CONCLUSIONS: Excess renal risk in men may, at least in part, be related to higher levels of proteinuria in men compared with women.

Variations in 24-Hour BP Profiles in Cohorts of Patients with Kidney Disease around the World: The I-DARE Study.

BACKGROUND AND OBJECTIVES: Ambulatory BP is increasingly recognized as a better measure of the risk for adverse outcomes related to hypertension, an important comorbidity in patients with CKD. Varying definitions of white-coat and masked hypertension have made it difficult to evaluate differences in prevalence of these BP patterns across CKD cohorts. DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS: The International Database of Ambulatory BP in Renal Patients collaborative group established a large database of demographic, clinical, and ambulatory BP data from patients with CKD from cohorts in Italy, Spain, the Chronic Renal Insufficiency Cohort (CRIC) and the African American Study of Kidney Disease and Hypertension Cohort Study (AASK) in the United States, and the CKD Japan Cohort (CKD-JAC). Participants (n=7518) with CKD were included in the present analyses. Cutoffs for defining controlled BP were 140/90 mm Hg for clinic and 130/80 mm Hg for 24-hour ambulatory BP. RESULTS: Among those with controlled clinic BP, compared with CKD-JAC, AASK participants were more likely to have masked hypertension (prevalence ratio [PR], 1.21; 95% confidence interval [95% CI], 1.04 to 1.41) whereas CRIC (PR, 0.82; 0.72 to 0.94), Italian (PR, 0.73; 0.56 to 0.95), and Spanish participants (PR, 0.75; 0.64 to 0.88) were less likely. Among those with elevated clinic BP, AASK participants were more likely to have sustained hypertension (PR, 1.22; 95% CI, 1.13 to 1.32) whereas Italian (PR, 0.78; 0.70 to 0.87) and Spanish participants (PR, 0.89; 0.82 to 0.96) were less likely, although CRIC participants had similar prevalence as CKD-JAC. Prevalence of masked and sustained hypertension was elevated in males, patients with diabetes, participants on four or more antihypertensives, and those with moderate-to-severe proteinuria. CONCLUSIONS: In a large, multinational database, the prevalence of masked and sustained hypertension varied across cohorts independent of important comorbidities.

Cardiorenal prognosis by residual proteinuria level in diabetic chronic kidney disease: pooled analysis of four cohort studies.

Background: No study has assessed whether the prognosis of coexisting diabetes mellitus and chronic kidney disease (DM-CKD) is dictated by DM per se or by the extent of proteinuria. Methods: In this pooled analysis of four prospective studies in CKD patients treated with drugs inhibiting the renin-angiotensin system, we compared the risk of all-cause mortality, fatal and non-fatal cardiovascular (CV) events and end-stage renal disease (ESRD) between patients with (n = 693) and without diabetes (n = 1481) stratified by proteinuria level (<0.15, 0.15-0.49, 0.5-1 and >1 g/day). Results: The group with DM-CKD was older (69 ± 11 versus 65 ± 15 years), had a higher body mass index (29.6 ± 5.4 versus 27.5 ± 4.8 kg/m2) and systolic blood pressure (143 ± 19 versus 136 ± 18 mmHg), prevalent CV disease (48% versus 29%) and lower estimated glomerular filtration rate (34.5 ± 17.9 versus 36.6 ± 19.0 mL/min/1.73 m2). During 4.07 years of follow-up, there were 466 patients with ESRD, 334 deaths and 401 CV events occurred. In the subgroup with urine protein <0.15 g/day (N = 662), the risks of ESRD, CV events and mortality were similar in diabetic and non-diabetic patients. Conversely, in DM-CKD patients, the mortality risk was higher in proteinuric patients {hazard ratio 1.92 [95% confidence interval (CI) 1.25-2.95); 1.99 (1.26-3.15) and 1.98 (1.28-3.06) for proteinuria 0.15-0.49, 0.5-1 and >1 g/day, respectively}, whereas in non-diabetics the mortality risk increased only for proteinuria 0.5-1 g/day [HR 1.60 (95% CI 1.07-2.40)] and >1 g/day [HR 1.69 (95% CI1.20-2.55)]. In both groups, CV risk had a trend similar to that of mortality. ESRD risk increased progressively across strata >0.5 g/day independent of diabetic status. Conclusions: We provide evidence that patients with non-proteinuric DM-CKD are not exposed to higher cardiorenal risk. In contrast, in the presence of moderate proteinuria and diabetes per se is associated with a higher risk of mortality and CV events, whereas the entity of abnormal proteinuria modulates ESRD risk independent of diabetes.

The role of renal response to amino acid infusion and oral protein load in normal kidneys and kidney with acute and chronic disease.

PURPOSE OF REVIEW: High protein intake and hyperfiltration have been a focus of major interest as potential mechanism(s) of progression of renal disease. This review will examine: the renal response to a protein meal or amino acid infusion and its use to test the renal functional reserve (RFR); new methods to evaluate RFR; the use of RFR in various pathophysiologic conditions. RECENT FINDINGS: The renal response to protein/amino acid infusion involves several mechanisms, including nitric oxide, insulin, glucagon, arginine vasopressin, urea, the renal N-Methyl-D-Aspartate Glutamate receptor and modulation of the activity of the tubuloglomerular feedback system. Dose-response studies to evaluate RFR suggest the presence of a potential ceiling. The utilization of a noninvasive technique such as Doppler ultrasonography is trying to simplify the measurement of RFR and to bring this test into different clinical settings. There is increased interest in the presence or absence of RFR in patients with acute kidney injury, hypertension, chronic kidney disease, and its potential long-term implication regarding renal function. SUMMARY: The renal response to protein may help us understand the relationship between hyperfiltration, progression of renal disease, and other conditions (overall mortality, cardiovascular complications, and so on) currently being explored.

Urine Fibrosis Markers and Risk of Allograft Failure in Kidney Transplant Recipients: A Case-Cohort Ancillary Study of the FAVORIT Trial.

BACKGROUND: Kidney tubulointerstitial fibrosis marks risk for allograft failure in kidney transplant recipients, but is poorly captured by estimated glomerular filtration rate (eGFR) or urine albumin-creatinine ratio (ACR). Whether urinary markers of tubulointerstitial fibrosis can noninvasively identify risk for allograft failure above and beyond eGFR and ACR is unknown. STUDY DESIGN: Case-cohort study. SETTING & PARTICIPANTS: The FAVORIT (Folic Acid for Vascular Outcome Reduction in Transplantation) Trial was a randomized double-blind trial testing vitamin therapy to lower homocysteine levels in stable kidney transplant recipients. We selected a subset of participants at random (n=491) and all individuals with allograft failure during follow-up (cases; n=257). PREDICTOR: Using spot urine specimens from the baseline visit, we measured 4 urinary proteins known to correlate with tubulointerstitial fibrosis on biopsy (urine α1-microglobulin [A1M], monocyte chemoattractant protein 1 [MCP-1], and procollagen type III and type I amino-terminal amino pro-peptide). OUTCOME: Death-censored allograft failure. RESULTS: In models adjusted for demographics, chronic kidney disease risk factors, eGFR, and ACR, higher concentrations of urine A1M (HR per doubling, 1.73; 95% CI, 1.43-2.08) and MCP-1 (HR per doubling, 1.60; 95% CI, 1.32-1.93) were strongly associated with allograft failure. When additionally adjusted for concentrations of other urine fibrosis and several urine injury markers, urine A1M (HR per doubling, 1.76; 95% CI, 1.27-2.44]) and MCP-1 levels (HR per doubling, 1.49; 95% CI, 1.17-1.89) remained associated with allograft failure. Urine procollagen type III and type I levels were not associated with allograft failure. LIMITATIONS: We lack kidney biopsy data, BK titers, and HLA antibody status. CONCLUSIONS: Urine measurement of tubulointerstitial fibrosis may provide a noninvasive method to identify kidney transplant recipients at higher risk for future allograft failure, above and beyond eGFR and urine ACR.

Associations of Left Ventricular Hypertrophy and Geometry with Adverse Outcomes in Patients with CKD and Hypertension.

BACKGROUND AND OBJECTIVES: Left ventricular hypertrophy (LVH) and abnormal left ventricular (LV) geometry predict adverse outcomes in the general and hypertensive populations, but findings in CKD are still inconclusive. DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS: We enrolled 445 patients with hypertension and CKD stages 2-5 in two academic nephrology clinics in 1999-2003 who underwent both echocardiography and ambulatory BP monitoring. LVH (LV mass >100 g/m(2) [women] and >131 g/m(2) [men]) and relative wall thickness (RWT) were used to define LV geometry: no LVH and RWT≤0.45 (normal), no LVH and RWT>0.45 (remodeling), LVH and RWT≤0.45 (eccentric), and LVH and RWT>0.45 (concentric). We evaluated the prognostic role of LVH and LV geometry on cardiovascular (CV; composite of fatal and nonfatal events) and renal outcomes (composite of ESRD and all-cause death). RESULTS: Age was 64.1±13.8 years old; 19% had diabetes, and 22% had CV disease. eGFR was 39.9±20.2 ml/min per 1.73 m(2). LVH was detected in 249 patients (56.0%); of these, 125 had concentric LVH, and 124 had eccentric pattern, whereas 71 patients had concentric remodeling. Age, women, anemia, and nocturnal hypertension were independently associated with both concentric and eccentric LVH, whereas diabetes and history of CV disease associated with eccentric LVH only, and CKD stages 4 and 5 associated with concentric LVH only. During follow-up (median, 5.9 years; range, 0.04-15.3), 188 renal deaths (112 ESRD) and 103 CV events (61 fatal) occurred. Using multivariable Cox analysis, concentric and eccentric LVH was associated with higher risk of CV outcomes (hazard ratio [HR], 2.59; 95% confidence interval [95% CI], 1.39 to 4.84 and HR, 2.79; 95% CI, 1.47 to 5.26, respectively). Similarly, greater risk of renal end point was detected in concentric (HR, 2.33; 95% CI, 1.44 to 3.80) and eccentric (HR, 2.30; 95% CI, 1.42 to 3.74) LVH. Sensitivity analysis using LVH and RWT separately showed that LVH but not RWT was associated with higher cardiorenal risk. CONCLUSIONS: In patients with CKD, LVH is a strong predictor of the risk of poor CV and renal outcomes independent from LV geometry.

Reassessment of Ambulatory Blood Pressure Improves Renal Risk Stratification in Nondialysis Chronic Kidney Disease: Long-Term Cohort Study.

In nondialysis chronic kidney disease, ambulatory blood pressure (ABP) performs better than clinic BP in predicting outcome, but whether repeated assessment of ABP further refines prognosis remains ill-defined. We recruited 182 consecutive hypertensive patients with nondialysis chronic kidney disease who underwent 2 ABPs 12 months apart to evaluate the enhancement in risk stratification provided by a second ABP obtained 1 year after baseline on the risk (hazard ratio and 95% confidence interval) of composite renal end point (death, chronic dialysis, and estimated glomerular filtration rate decline ≥40%). The difference in daytime and nighttime systolic BP between the 2 ABPs (daytime and nighttime bias) was added to a survival model including baseline ABP. Net reclassification improvement was also calculated. Age was 65.6±13.4 years; 36% had diabetes mellitus and 36% had previous cardiovascular event; estimated glomerular filtration rate was 42.2±19.6 mL/min per 1.73 m(2), and clinic BP was 145±18/80±11 mm Hg. Baseline ABP (daytime, 131±16/75±10 and nighttime, 122±18/66±10 mm Hg) and daytime/nighttime BP goals (58.2% and 43.4%) did not change at month 12. Besides baseline ABP values, bias for daytime and nighttime systolic BP linearly associated with renal outcome (1.12, 1.04-1.21 and 1.18, 1.08-1.29 for every 5-mm Hg increase, respectively). Classification of patients at risk improved when considering nighttime systolic level at second ABP (net reclassification improvement, 0.224; 95% confidence interval, 0.005-0.435). Patients with first and second ABPs above target showed greater renal risk (2.15, 1.29-3.59 and 1.71, 1.07-2.72, for daytime and nighttime, respectively). In nondialysis chronic kidney disease, reassessment of ABP at 1 year further refines renal prognosis; such reassessment should specifically be considered in patients with uncontrolled BP at baseline.

Assessment of achieved clinic and ambulatory blood pressure recordings and outcomes during treatment in hypertensive patients with CKD: a multicenter prospective cohort study.

BACKGROUND: We investigated the effect of having clinic and/or ambulatory blood pressures (BPs) not at goal on cardiorenal risk in patients with non-dialysis-dependent chronic kidney disease (CKD). STUDY DESIGN: Multicenter prospective study. SETTING & PARTICIPANTS: 489 consecutive hypertensive patients with CKD (stages 1-5) with concomitant assessment of ambulatory and clinic BPs followed up in tertiary nephrology clinics. PREDICTORS: Achievement of goal for ambulatory (day- and night-time BPs <135/85 and <120/70mmHg, respectively) and clinic (<140/90mmHg) BPs was used to create 4 BP groups: clinic and ambulatory BPs at goal (group 1), clinic BP above goal and ambulatory BP at goal (group 2), clinic BP at goal and ambulatory BP above goal (group 3), and clinic and ambulatory BPs above goal (group 4). OUTCOMES: Composite cardiovascular event outcome (fatal and nonfatal myocardial infarction, congestive heart failure, stroke, revascularization, peripheral vascular disease, and nontraumatic amputation) and a composite renal outcome (maintenance dialysis therapy or death). MEASUREMENTS: Clinic and 24-hour ambulatory BPs. RESULTS: Mean age was 64.4±14.2 (SD) years; 41% were women, and diabetes and previous cardiovascular disease were present in 36% and 30%, respectively. Groups 1-4 contained 16.8%, 22.1%, 14.5%, and 46.6%, respectively, of the overall number of participants. Median follow-up was 5.2 years. Compared to group 1, the adjusted risk of the composite cardiovascular outcome was higher in groups 3 (HR, 3.17; 95%CI, 1.50-6.69) and 4 (HR, 2.83; 95%CI, 1.50-5.34), but not in group 2 (HR, 1.55; 95%CI, 0.75-3.19). Similarly, the risk of the composite renal outcome was higher in groups 3 (HR, 3.59; 95%CI, 2.05-6.27) and 4 (HR, 2.96; 95%CI, 1.83-4.78), but not group 2 (HR, 1.24; 95%CI, 0.67-2.27). Sensitivity analyses confirmed that these results were independent from the thresholds used for defining groups. LIMITATIONS: Only white patients were enrolled. Observational design does not allow for causality to be established. CONCLUSIONS: In patients with treated CKD, clinic BP above goal and ambulatory BP at goal identify a low-risk condition, whereas clinic BP at goal and ambulatory BP above goal are associated with higher cardiorenal risk, similar to that observed in patients with both clinic and ambulatory BPs above goal.

Sodium/glucose cotransporter 2 inhibitors and prevention of diabetic nephropathy: targeting the renal tubule in diabetes.

Optimal prevention and treatment of chronic kidney disease in diabetes requires implementing therapies that specifically interfere with the pathogenesis of diabetic nephropathy. In this regard, significant attention has been given to alterations of the proximal tubule and resulting changes in glomerular filtration rate. At the onset of diabetes mellitus, hyperglycemia causes increases in proximal tubular reabsorption secondary to induction of tubular growth with associated increases in sodium/glucose cotransport. The increase in proximal reabsorption leads to a decrease in solute load to the macula densa, deactivation of the tubuloglomerular feedback, and increases in glomerular filtration rate. Because glomerular hyperfiltration currently is recognized as a risk factor for progression of kidney disease in diabetic patients, limiting proximal tubular reabsorption constitutes a potential target to reduce hyperfiltration. The recent introduction of sodium/glucose cotransporter 2 (SGLT2) inhibitors opens new therapeutic perspectives for this high-risk patient population. Experimental studies have shown that these new agents attenuate the progressive nature of diabetic nephropathy by blood glucose-dependent and -independent mechanisms. SGLT2 inhibition may prevent glomerular hyperfiltration independent of the effect of lowering blood glucose levels while limiting kidney growth, inflammation, and albuminuria through reductions in blood glucose levels. Clinical data for the potential role of the proximal tubule in the pathophysiology of diabetic nephropathy and the nephroprotective effects of SGLT2 inhibitors currently are limited compared to the more extensive experimental literature. We review the evidence supporting this working hypothesis by integrating the experimental findings with the available clinical data.

Prevalence and prognostic role of resistant hypertension in chronic kidney disease patients.

OBJECTIVES: This study sought to evaluate in chronic kidney disease (CKD) prevalence and prognosis of true resistant hypertension (RH) (i.e., confirmed by ambulatory blood pressure [ABP] monitoring). BACKGROUND: In CKD, uncontrolled hypertension is a major risk factor, but no study has properly investigated the role of RH. METHODS: We prospectively studied 436 hypertensive CKD patients under nephrology care. Four groups were constituted by combining 24-h ABP with diagnosis of RH (office blood pressure ≥130/80 mm Hg, despite adherence to ≥3 full-dose antihypertensive drugs including a diuretic agent or ≥4 drugs): control (ABP <125/75 mm Hg without RH); pseudoresistance (ABP <125/75 mm Hg with RH); sustained hypertension (ABP ≥125/75 mm Hg without RH); and true resistance (ABP ≥125/75 mm Hg with RH). Endpoints of survival analysis were renal (end-stage renal disease or death) and cardiovascular events (fatal and nonfatal cardiovascular event). RESULTS: Age was 65 ± 14 years, men 58%, diabetes 36%, cardiovascular disease 30%, median proteinuria 0.24 (interquartile range 0.09 to 0.83) g/day, estimated glomerular filtration rate 43 ± 20 ml/min/1.73 m(2), office blood pressure 146 ± 19/82 ± 12 mm Hg, and 24-h ABP 129 ± 17/72 ± 10 mm Hg. True resistant patients were 22.9%, and pseudoresistant patients were 7.1%, whereas patients with sustained hypertension were 42.9%, and control subjects were 27.1%. Over 57 months of follow-up, 109 cardiovascular events and 165 renal events occurred. Cardiovascular risk (hazard ratio [95% confidence interval]) was 1.24 (0.55 to 2.78) in pseudoresistance, 1.11 (0.67 to 1.84) in sustained hypertension, and 1.98 (1.14 to 3.43) in true resistance, compared with control subjects. Corresponding hazards for renal events were 1.18 (0.45 to 3.13), 2.14 (1.35 to 3.40), and 2.66 (1.62 to 4.37). CONCLUSIONS: In CKD, pseudoresistance is not associated with an increased cardio-renal risk, and sustained hypertension predicts only renal outcome. True resistance is prevalent and identifies patients carrying the highest cardiovascular risk.

A trial of 2 strategies to reduce nocturnal blood pressure in blacks with chronic kidney disease.

The objective of our study was to determine the effects of 2 antihypertensive drug dose schedules (PM dose and add-on dose) on nocturnal blood pressure (BP) in comparison with usual therapy (AM dose) in blacks with hypertensive chronic kidney disease and controlled office BP. In a 3-period, crossover trial, former participants of the African American Study of Kidney Disease were assigned to receive the following 3 regimens, each lasting 6 weeks, presented in random order: AM dose (once-daily antihypertensive medications taken in the morning), PM dose (once-daily antihypertensives taken at bedtime), and add-on dose (once-daily antihypertensives taken in the morning and an additional antihypertensive medication before bedtime [diltiazem 60-120 mg, hydralazine 25 mg, or additional ramipril 5 mg]). Ambulatory BP monitoring was performed at the end of each period. The primary outcome was nocturnal systolic BP. Mean age of the study population (n=147) was 65.4 years, 64% were men, and mean estimated glomerular filtration rate was 44.9 mL/min per 1.73 m(2). At the end of each period, mean (SE) nocturnal systolic BP was 125.6 (1.2) mm Hg in the AM dose, 123.9 (1.2) mm Hg in the PM dose, and 123.5 (1.2) mm Hg in the add-on dose. None of the pairwise differences in nocturnal, 24-hour, and daytime systolic BP was statistically significant. Among blacks with hypertensive chronic kidney disease, neither PM (bedtime) dosing of once-daily antihypertensive nor the addition of drugs taken at bedtime significantly reduced nocturnal BP compared with morning dosing of antihypertensive medications.

Relationship between ambulatory BP and clinical outcomes in patients with hypertensive CKD.

BACKGROUND AND OBJECTIVES: Abnormal ambulatory BP (ABP) profiles are commonplace in CKD, yet the prognostic value of ABP for renal and cardiovascular outcomes is uncertain. This study assessed the relationship of baseline ABP profiles with CKD progression and subsequent cardiovascular outcomes to determine the prognostic value of ABP beyond that of clinic BP measurements. DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS: Between 2002 and 2003, 617 African Americans with hypertensive CKD treated to a clinic BP goal of <130/80 mmHg were enrolled in this prospective, observational study. Participants were followed for a median of 5 years. Primary renal outcome was a composite of doubling of serum creatinine, ESRD, or death. The primary cardiovascular outcome was a composite of myocardial infarction, hospitalized congestive heart failure, stroke, revascularization procedures, cardiovascular death, and ESRD. RESULTS: Multivariable Cox proportional hazard analysis showed that higher 24-hour systolic BP (SBP), daytime, night-time, and clinic SBP were each associated with subsequent renal (hazard ratio, 1.17-1.28; P<0.001) and cardiovascular outcomes (hazard ratio, 1.22-1.32; P<0.001). After controlling for clinic SBP, ABP measures were predictive of renal outcomes in participants with clinic SBP <130 mmHg (P<0.05 for interaction). ABP predicted cardiovascular outcomes with no interaction based on clinic BP control. CONCLUSIONS: ABP provides additional information beyond that of multiple clinic BP measures in predicting renal and cardiovascular outcomes in African Americans with hypertensive CKD. The primary utility of ABP in these CKD patients was to identify high-risk individuals among those patients with controlled clinic BP.

Aberrant tubuloglomerular feedback and HIF-1α confer resistance to ischemia after subtotal nephrectomy.

Nephron loss in a diseased kidney invokes adaptations in the remaining nephrons. Whether and how these adaptations condition the response of the kidney to injury is not known. We examined the susceptibility of the kidney after subtotal (5/6th) nephrectomy (STN) to ischemic injury in rats. GFR in STN kidneys did not significantly change after ischemia reperfusion (IR), whereas GFR fell by 70% after IR in unilateral nephrectomy controls. In micropuncture experiments, single-nephron GFR responses mirrored the whole-kidney responses: in STN, single-nephron GFR decreased by 7% after IR compared with 28% in controls. Furthermore, we found that tubuloglomerular feedback, a mechanism that links proximal tubular injury to a fall in GFR, was inoperative in STN but was normal in controls. Restoration of normal feedback in STN attenuated the functional resistance to IR. In addition to the functional resilience, the morphology of the kidney was better preserved in STN. In STN kidneys, the S3 segment of the proximal tubule, normally injured after ischemia, constitutively expressed hypoxia-inducible factor-1α (HIF-1α), which is cytoprotective in ischemia. Inducing HIF before IR improved GFR in control animals, and inhibiting the HIF target heme-oxygenase-1 before IR reduced GFR in STN animals. Taken together, these data suggest that fewer functioning nephrons in a diseased kidney do not increase the susceptibility to injury, but rather, hemodynamic and molecular adaptations in the remnant nephrons precondition them against ischemic injury.

Prognostic role of ambulatory blood pressure measurement in patients with nondialysis chronic kidney disease.

BACKGROUND: Ambulatory blood pressure (BP) measurement allows a better risk stratification in essential hypertension compared with office blood pressure measurement, but its prognostic role in nondialysis chronic kidney disease has been poorly investigated. METHODS: The prognostic role of daytime and nighttime systolic BP (SBP) and diastolic BP (DBP) in comparison with office measurements was evaluated in 436 consecutive patients with chronic kidney disease. Primary end points were time to renal death (end-stage renal disease or death) and time to fatal and nonfatal cardiovascular events. Quintiles of BP were used to classify patients. RESULTS: The mean (SD) age of the patients was 65.1 (13.6) years, and the glomerular filtration rate was 42.9 (19.7) mL/min/1.73 m(2); 41.7% of the participants were women, 36.5% had diabetes, and 30.5% had cardiovascular disease. Office-measured SBP/DBP values were 146 (19)/82 (12) mm Hg; daytime SBP/DBP was 131 (17)/75 (11) mm Hg, and nighttime SBP/DBP was 122 (20)/66 (10) mm Hg. During follow-up (median, 4.2 years), 155 and 103 patients reached the renal and cardiovascular end points, respectively. Compared with a daytime SBP of 126 to 135 mm Hg, patients with an SBP of 136 to 146 mm Hg and those with an SBP higher than 146 mm Hg had an increased adjusted risk of the cardiovascular end point (hazard ratio [HR], 2.23; 95% confidence interval [CI], 1.13-4.41 and 3.07; 1.54-6.09) and renal death (1.72; 1.02-2.89 and 1.85; 1.11-3.08). Nighttime SBPs of 125 to 137 mm Hg and higher than 137 mm Hg also increased the risk of the cardiovascular end point (HR, 2.52; 95% CI, 1.11-5.71 and 4.00; 1.77-9.02) and renal end point (1.87; 1.03-3.43 and 2.54; 1.41-4.57) with respect to the reference SBP value of 106-114 mm Hg. Office measurement of BP did not predict the risk of the renal or cardiovascular end point. Patients who were nondippers and those who were reverse dippers had a greater risk of both end points. CONCLUSION: In chronic kidney disease, ambulatory BP measurement and, in particular, nighttime BP measurement, allows more accurate prediction of renal and cardiovascular risk; office measurement of BP does not predict any outcome.

Hypertension management in chronic kidney disease: translating guidelines into daily practice.

BACKGROUND: Whether nephrology management improves over time achievement of blood pressure (BP) goal (<130/<80 mm Hg) in nondialysis CKD is still ill-defined. This historical cohort analysis evaluated the relationship between 1-year nephrology management and BP control in 275 incident CKD patients in an academic renal clinic. METHODS: Comparative analysis between referral and month-12 visit. RESULTS: Estimated glomerular filtration rate (GFR) was 42.1 ± 15.5 ml/min per 1.73 m2 and median proteinuria 0.20 g/24 hours. From baseline to month-12 visit, BP decreased from 148 ± 23 / 81 ± 12 mm Hg to 136 ± 18 / 76 ± 11 mm Hg, with BP goal prevalence increasing from 13.8% to 33.8%. We stratified patients into at-goal and not-at-goal on the basis of month-12 BP levels. Regression analysis identified diabetes (odds ratio [OR] = 1.96; 95% confidence interval [95% CI], 1.07-3.56) and basal systolic BP (OR=1.12; 95% CI, 1.03-1.21) as independent predictors of not-at-goal BP. The decrease in systolic/diastolic BP was smaller in not-at-goal versus at-goal patients (-7/3 mm Hg vs. -21/9 mm Hg); in not-at-goal reduction was, however, significant versus baseline (p<0.001) and coupled with a similar decline in proteinuria (p<0.001). CONCLUSIONS: Sustained nephrology management improves hypertension control in CKD, but achievement of BP goals remains suboptimal, with high systolic BP and diabetes being the main problems. Further studies are needed to verify the clinical significance of BP and proteinuria changes in patients whose BP remains above target levels.