Scott Reule

Renal Function Profile in White Kidney Donors: The First 4 Decades

Previous studies reported the risk of ESRD after kidney donation, but not the renal outcomes that precede ESRD. Here, we estimated the risk of proteinuria, reduced GFR, and ESRD in 3956 white kidney donors, assessed the contribution of postdonation hypertension and diabetes to these outcomes, and developed a risk calculator. After a mean±SD follow-up of 16.6±11.9 years, 215 (6.1%) donors developed proteinuria. Men had a higher risk of proteinuria (hazard ratio [HR], 1.56; 95% confidence interval [95% CI], 1.18 to 2.05; P<0.001) as did those with higher body mass index (HR, 1.10; 95% CI, 1.06 to 1.13; P<0.001). In all, 1410 (36%) donors reached an eGFR<60 ml/min per 1.73 m(2), and 112 (2.8%) donors had either an eGFR<30 ml/min per 1.73 m(2) or ESRD (28 donors developed ESRD). An eGFR<30 ml/min per 1.73 m(2) or ESRD associated with older age (HR, 1.07; 95% CI, 1.05 to 1.09; P<0.001), higher body mass index (HR, 1.08; 95% CI, 1.04 to 1.13; P<0.001), and higher systolic BP (HR, 1.02; 95% CI, 1.00 to 1.04; P=0.01) at donation. Postdonation diabetes and hypertension associated with a fourfold higher risk of proteinuria and a >2-fold higher risk of ESRD. Models predicting proteinuria and reduced eGFR performed well (C-index 0.77-1.00). In conclusion, severe reduction in GFR and ESRD after kidney donation were uncommon and were highly associated with postdonation diabetes and hypertension. Furthermore, information available before donation may predict long-term renal outcomes in white living kidney donors.

ESRD From Lupus Nephritis in the United States, 1995–2010

BACKGROUND AND OBJECTIVES While ESRD from lupus nephritis (ESLN) increased in the United States after the mid-1990s and racial disparities were apparent, current trends are unknown. DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS Retrospective US Renal Data System data (n=1,557,117) were used to calculate standardized incidence ratios (standardized to 1995-1996) and outcomes of ESLN (n=16,649). For events occurring after initiation of RRT, follow-up ended on June 30, 2011. RESULTS Overall ESLN rates (95% confidence intervals [95% CIs]) in 1995-1996 were 3.1 (2.9 to 3.2) cases per million per year. Rates were higher for subgroups characterized by African-American race (11.1 [95% CI, 10.3 to 11.9]); other race (4.9 [95% CI, 4.0 to 5.8]); female sex (4.9 [95% CI, 4.6 to 5.2]); and ages 20-29 years (4.9 [95% CI, 4.4 to 5.4]), 30-44 years (4.6 [95% CI, 4.2 to 5.0]), and 45-64 years (4.0 [95% CI, 3.7 to 4.4]). Standardized incidence ratios for the overall population in subsequent biennia were 1.19 (1.14 to 1.24) in 1997-1998, 1.17 (1.12 to 1.22) in 1999-2000, 1.17 (1.12 to 1.22) in 2001-2002, 1.21 (1.16 to 1.26) in 2003-2004, 1.18 (1.13 to 1.23) in 2005-2006, 1.16 (1.11 to 1.21) in 2007-2008, and 1.05 (1.01 to 1.09) in 2009-2010, respectively. During a median (interquartile range) follow-up of 4.4 (6.3) years, 42.6% of patients with ESLN died, 45.3% were listed for renal transplant, and 28.7% underwent transplantation. Patients with ESLN were more likely than matched controls to be listed for and to undergo transplantation, and mortality rates were similar. Among patients with ESLN, African Americans were less likely to undergo transplantation (adjusted hazard ratio, 0.54 [0.51 to 0.58]) and more likely to die prematurely (adjusted hazard ratio, 1.23 [1.17 to 1.30]). CONCLUSIONS While ESLN appears to have stopped increasing in the last decade, racial disparities in outcomes persist.

Heart Rate and Blood Pressure: Any Possible Implications for Management of Hypertension?

Hypertension is a common clinical problem and a major risk factor for cardiovascular disease and stroke. Elevated heart rate is associated with elevated blood pressure, increased risk for hypertension, and, among hypertensives, increased risk for cardiovascular disease. Despite these important relationships, heart rate is generally not a major consideration in choosing antihypertensive medications. In part, this is due to a lack of evidence supporting heart rate lowering as a therapeutic strategy in hypertension. Additionally, while there is a positive correlation between heart rate and peripheral blood pressure, there is an inverse relationship between heart rate and central blood pressure. The use of antihypertensive medications, specifically medications that affect heart rate, may not reliably reduce central blood pressure to a similar extent as observed peripherally. We review the relationship between heart rate and peripheral and central blood pressure, with a focus on the implications for chronotropic therapy in hypertension.

ESRD From Autosomal Dominant Polycystic Kidney Disease in the United States, 2001-2010

BACKGROUND Autosomal dominant polycystic kidney disease (ADPKD) is amenable to early detection and specialty care. Thus, while important to patients with the condition, end-stage renal disease (ESRD) from ADPKD also may be an indicator of the overall state of nephrology care. STUDY DESIGN Retrospective cohort study of temporal trends in ESRD from ADPKD and pre-renal replacement therapy (RRT) nephrologist care, 2001-2010 (n = 23,772). SETTING & PARTICIPANTS US patients who initiated maintenance RRT from 2001 through 2010 (n = 1,069,343) from US Renal Data System data. PREDICTOR ESRD from ADPKD versus from other causes for baseline characteristics and clinical outcomes; interval 2001-2005 versus 2006-2010 for comparisons of cohort of patients with ESRD from ADPKD. OUTCOMES Death, wait-listing for kidney transplant, kidney transplantation. MEASUREMENTS US census data were used as population denominators. Poisson distribution was used to compute incidence rates (IRs). Incidence ratios were standardized to rates in 2001-2002 for age, sex, and race/ethnicity. Patients with and without ADPKD were matched to compare clinical outcomes. Poisson regression was used to calculate IRs and adjusted HRs for clinical events after inception of RRT. RESULTS General population incidence ratios in 2009-2010 were unchanged from 2001-2002 (incidence ratio, 1.02). Of patients with ADPKD, 48.1% received more than 12 months of nephrology care before RRT; preemptive transplantation was the initial RRT in 14.3% and fistula was the initial hemodialysis access in 35.8%. During 4.9 years of follow-up, patients with ADPKD were more likely to be listed for transplantation (IR, 11.7 [95% CI, 11.5-12.0] vs 8.4 [95% CI, 8.2-8.7] per 100 person-years) and to undergo transplantation (IR, 9.8 [95% CI, 9.5-10.0] vs 4.8 [95% CI, 4.7-5.0] per 100 person-years) and less likely to die (IR, 5.6 [95% CI, 5.4-5.7] vs 15.5 [95% CI, 15.3-15.8] per 100 person-years) than matched controls without ADPKD. LIMITATIONS Retrospective nonexperimental registry-based study of associations; cause-and-effect relationships cannot be determined. CONCLUSIONS Although outcomes on dialysis therapy are better for patients with ADPKD than for those without ADPKD, access to predialysis nephrology care and nondeclining ESRD rates may be a cause for concern.

Low birthweight and risk of albuminuria in living kidney donors.

Low birthweight is linked to hypertension, chronic kidney disease and even end‐stage renal disease. We hypothesized that living kidney donors born with lower birthweight may be at increased risk of hypertension, albuminuria, or reduced GFR beyond what is typical following uninephrectomy. Two hundred fifty‐seven living kidney donors who donated at the University of Minnesota between 1967 and 2005 underwent iohexol GFR and urinary albumin excretion measurements. Predictors of iohexol GFR <60 mL/min/1.73 m2, albuminuria, and hypertension were examined using logistic regression. Predictors examined include age at GFR measurement, time since donation, BMI, gender, serum creatinine level (at donation and GFR measurement), systolic and diastolic blood pressure, race, and birthweight. The latter was obtained through self‐report and verified through birth certificates and family members. Older age, higher BMI, and time from donation were associated with reduced GFR. Older age and higher BMI were also associated with hypertension. Birthweight was not associated with GFR <60 mL/min/1.73 m2: OR=0.70, 95% CI (0.28, 1.74), p = 0.45 or hypertension: OR=0.92, 95% CI (0.46, 1.84), p = 0.82 but was associated with albuminuria: OR=0.37, 95% CI (0.15, 0.92), p = 0.03. These data further strengthen the link between low birthweight and potential adverse renal outcomes.

ESRD due to Multiple Myeloma in the United States, 2001–2010

Although management of multiple myeloma has changed substantially in the last decade, it is unknown whether the burden of ESRD due to multiple myeloma has changed, or whether survival of patients with multiple myeloma on RRT has improved. Regarding ESRD due to multiple myeloma necessitating RRT in the United States, we evaluated temporal trends between 2001 and 2010 for demography-adjusted incidence ratios, relative to rates in 2001-2002, and mortality hazards from RRT initiation, relative to hazards in 2001-2002. In this retrospective cohort study, we used the US Renal Data System database (n=1,069,343), 2001-2010, to identify patients with ESRD due to multiple myeloma treated with RRT (n=12,703). Demography-adjusted incidence ratios of ESRD from multiple myeloma decreased between 2001-2002 and 2009-2010 in the overall population (demography-adjusted incidence ratio 0.82; 95% confidence interval, 0.79 to 0.86) and in most demographic subgroups examined. Mortality rates were 86.7, 41.4, and 34.4 per 100 person-years in the first 3 years of RRT, respectively, compared with 32.3, 20.6, and 21.3 in matched controls without multiple myeloma. Unadjusted mortality hazards ratios declined monotonically after 2004 to a value of 0.72; 95% confidence interval, 0.67 to 0.77 in 2009-2010, and declines between 2001-2002 and 2008-2009 were observed (P<0.05) in most demographic subgroups examined. Findings were similar when adjustment was made for demographic characteristics, comorbidity markers, and laboratory test values. These data suggest the incidence of RRT from multiple myeloma in the United States has decreased in the last decade, and clinically meaningful increases in survival have occurred for these patients.

The renin-aldosterone axis in kidney transplant recipients and its association with allograft function and structure

The level of the renin-angiotensin-aldosterone system (RAAS) activity in kidney transplant recipients has not been extensively studied or serially profiled. To describe this axis and to determine its association with GFR change, interstitial expansion and end-stage renal disease (ESRD) we measured plasma renin activity (PRA) and plasma aldosterone levels annually for 5 years in 153 kidney transplant recipients randomly assigned to losartan or placebo. PRA and plasma aldosterone levels were in the normal range at all times and did not vary by immunosuppression regimen. Those on losartan exhibited higher PRA but similar plasma aldosterone levels. Neither baseline nor serial PRA or plasma aldosterone levels were associated with GFR decline, proteinuria or interstitial expansion. Losartan use, [HR 0.48 (95% CI 0.21–1.0), insignificant], and Caucasian donor, [HR 0.18 (95% CI 0.07–0.4), significant] were associated with less doubling of serum creatinine, death or ESRD. Hypertension, less than 3 HLA-matches, the combination of tacrolimus-rapamycin and acute rejection were associated with more events. Neither PRA nor plasma aldosterone levels were independently associated with this outcome. Higher serial plasma aldosterone levels were associated, however, with a significantly higher risk of ESRD, [HR 1.01 (95% CI 1.00–1.02)]. Thus, systemic RAAS is not overly activated in kidney transplant recipients but this may not reflect the intrarenal system. Importantly, plasma aldosterone levels may be associated with more ESRD.

Dual Renin-Angiotensin-Aldosterone System Inhibition for the Treatment of Diabetic Kidney Disease: Adverse Effects and Unfulfilled Promise

Diabetic nephropathy (DN) is a major complication of diabetes mellitus (DM) affecting individuals with type 1 or type 2 DM and is the leading cause of chronic kidney disease and end-stage kidney disease (ESKD) in the USA. Estimates of disease burden are projected to increase, with prevalence of nearly one in five adults by 2050. The role of renin-angiotensin-aldosterone system (RAAS) inhibition in delaying the progression of DN utilizing angiotensin-converting enzyme inhibitors or angiotensin receptor blockers has been well established in multiple controlled trials. Given greater reduction of proteinuria with dual RAAS blockade compared to monotherapy alone, the potential benefit of dual therapy on progression of DN has been tested in three large randomized clinical trials. Unfortunately, results from these studies demonstrated lack of benefit of dual blockade on renal or cardiovascular outcomes in patients with diabetes. The overall objectives of this review are to provide both the rationale for dual blockade as potential therapy as well as review the literature of its use in patients with DN.

Daily fluid intake and outcomes in kidney recipients: post hoc analysis from the randomized ABCAN trial.

Generous and even excessive fluid intake is routinely recommended to kidney transplant recipients despite minimal evidence to support this practice. We hypothesized that increased fluid intake, ascertained by 24‐h urine volume output, may adversely affect graft outcomes as it would impose an extra workload on a limited number of nephrons. Kidney transplant recipients who were randomized to losartan vs. placebo in the Angiotensin II Blockade for Chronic Allograft Nephropathy (ABCAN) trial (n = 153) underwent baseline, five‐yr biopsies, and annual iothalamate glomerular filtration rate assessment. Recipients with higher urine volume at randomization had higher urinary sodium and also higher urinary protein. The proportion using diuretics or CNI based regimens were similar across urinary volume tertiles. The highest urinary volume tertile (>2.56 L/d) did not predict the development of interstitial volume doubling or end‐stage renal disease (ESRD) from interstitial fibrosis/tubular atrophy (OR = 3.52, 95% CI 0.4, 31.24, p = 0.26), interstitial volume doubling or all‐cause ESRD (OR = 7.04, 95% CI 0.66, 74.87, p = 0.11), and was not associated with the conventional endpoint of doubling serum creatinine, all‐cause ESRD, or death (OR = 0.89, 95% CI 0.21, 3.71, p = 0.87). These results suggest that the current practice of liberal fluid intake may not be beneficial in low risk and mostly Caucasian transplant recipients.

End-Stage Renal Disease Attributed to Acute Tubular Necrosis in the United States, 2001-2010

Background/Aims: Though end-stage renal disease (ESRD) is increasingly attributed to acute tubular necrosis (ATN), contemporary trends in the rates of incidence and recovery of renal function are poorly defined. Hence, we set out to describe the clinical epidemiology of ESRD due to ATN between 2001 and 2010. Methods: We examined United States Renal Data System data (n = 1,070,490) for 2001 through 2010 to calculate the incidence rates and rates of renal recovery and death for patients with ESRD due to ATN treated with renal replacement therapy (RRT, n = 27,603). Results: Standardized incidence ratios increased between 2001-2002 and 2009-2010 in the overall population (ratio 2.14), having risen in all demographic subgroups examined. Recovery of renal function was more likely in patients with ATN than in matched controls (cumulative incidence 23% vs. 2% at 12 weeks, 34% vs. 4% at 1 year), as was death (cumulative incidence 38% vs. 27% at 1 year). Hazards ratios for renal recovery increased stepwise with year of RRT inception to 1.34 (95% confidence interval 1.24-1.45) for 2009-2010 (vs. 2001-2002). In contrast, hazards ratios for death declined stepwise to 0.83 (0.79-0.87) in 2009-2010. Conclusion: While the incidence of ESRD attributed to ATN has increased, prospects of renal recovery and survival have also increased. Despite substantial mortality risk on RRT, renal recovery is not a rare occurrence.