Prophylactic or Early Use of Eculizumab and Graft Survival in Kidney Transplant Recipients With Atypical Hemolytic Uremic Syndrome in the United States: Research Letter

Introduction:

Among kidney transplant recipients (KTRs) with end-stage kidney disease (ESKD) due to atypical hemolytic uremic syndrome (aHUS), recurrence is associated with poor allograft outcomes. We compared graft and patient survival of aHUS KTRs with and without prophylactic/early use of eculizumab, a monoclonal antibody that binds complement protein C5, at the time of transplantation.

Methods:

We conducted a retrospective cohort study using the United States Renal Data System. Out of 123 624 ESKD patients transplanted between January 1, 2008, and June 1, 2016, we identified 348 (0.28%) patients who had “hemolytic uremic syndrome” as the primary cause of ESKD. We then linked these patients to datasets containing the Healthcare Common Procedure Coding System (HCPCS) code for eculizumab infusion. Patients who received eculizumab prior to or within 30 days of transplant represented the exposure group. We calculated crude incidence rates and conducted exact logistic regression, adjusted for recipient age and sex, for the study outcomes of graft loss, death-censored graft loss, and mortality. We also estimated the average treatment effect (ATE) by propensity-score matching, to reduce the bias in the estimated treatment effect on graft loss.

Results:

Our final study cohort included 335 aHUS KTRs (23 received eculizumab, 312 did not), with a mean duration of follow-up of 5.8 ± 2.7 years. There were no significant differences in baseline demographic and clinical characteristics between the eculizumab versus non-eculizumab group. Patients who received prophylactic/early eculizumab were less likely to experience graft loss compared with those who did not receive eculizumab (0% vs 20%, P = .02), with an adjusted odds ratio of 0.13 (P = .02). In the propensity-score-matched sample, the ATE (eculizumab vs non-eculizumab) was −0.20 (95% confidence interval [CI] = −0.25 to −0.15, P < .001); thus, treatment was associated with an average of 20% reduction in graft loss. There was no significant difference in the risk of death between the 2 groups.

Conclusions:

Although there was no significant difference in the risk of death, prophylactic/early use of eculizumab was significantly associated with improved graft survival among aHUS KTRs. Given the high cost of eculizumab, randomized controlled trials are much needed to guide prophylactic strategies to prevent graft loss.

Global Epidemiology of End-Stage Kidney Disease and Disparities in Kidney Replacement Therapy

BACKGROUND

The global epidemiology of end-stage kidney disease (ESKD) reflects each nation's unique genetic, environmental, lifestyle, and sociodemographic characteristics. The response to ESKD, particularly regarding kidney replacement therapy (KRT), depends on local disease burden, culture, and socioeconomics. Here, we explore geographic variation and global trends in ESKD incidence and prevalence and examine variations in KRT modality, practice patterns, and mortality. We conclude with a discussion on disparities in access to KRT and strategies to reduce ESKD global burden and to improve access to treatment in low- and middle-income countries (LMICs).

SUMMARY

From 2003 to 2016, incidence rates of treated ESKD were relatively stable in many higher income countries but rose substantially predominantly in East and Southeast Asia. The prevalence of treated ESKD has increased worldwide, likely due to improving ESKD survival, population demographic shifts, higher prevalence of ESKD risk factors, and increasing KRT access in countries with growing economies. Unadjusted 5-year survival of ESKD patients on KRT was 41% in the USA, 48% in Europe, and 60% in Japan. Dialysis is the predominant KRT in most countries, with hemodialysis being the most common modality. Variations in dialysis practice patterns account for some of the differences in survival outcomes globally. Worldwide, there is a greater prevalence of KRT at higher income levels, and the number of people who die prematurely because of lack of KRT access is estimated at up to 3 times higher than the number who receive treatment. Key Messages: Many people worldwide in need of KRT as a life-sustaining treatment do not receive it, mostly in LMICs where health care resources are severely limited. This large treatment gap demands a focus on population-based prevention strategies and development of affordable and cost-effective KRT. Achieving global equity in KRT access will require concerted efforts in advocating effective public policy, health care delivery, workforce capacity, education, research, and support from the government, private sector, nongovernmental, and professional organizations.

Use of Percutaneous Coronary Intervention Among Black and White Patients With End-Stage Renal Disease in the United States

Background Racial disparities in invasive cardiac procedures such as percutaneous coronary intervention (PCI) in the general population are well documented; however, national-level data on such disparities in the end-stage renal disease (ESRD) population are lacking. We assessed racial differences in PCI between black and white patients with ESRD on maintenance dialysis. Methods and Results Using the US Renal Data System database, we abstracted Medicare inpatient procedure claims for PCI in a cohort of 268 575 Medicare-primary patients who initiated treatment on maintenance dialysis from January 1, 2009, through June 1, 2013. We conducted Cox regression analyses with PCI being the event, adjusted for demographic characteristics, Hispanic ethnicity, cause of ESRD, comorbidities, and socioeconomic factors. We also assessed the probability of PCI, accounting for death or transplant in competing risk regression models. The crude incidence rate of PCI among white patients was 25.8 per 1000 patient-years versus 15.5 per 1000 patient-years among black patients. Cox regression analyses demonstrated that black patients were significantly less likely to undergo PCI compared with white patients (adjusted hazard ratio: 0.64; 95% CI, 0.62-0.67; P<0.001). In the competing risk models, the racial gap for PCI among black and white patients remained significant with death (subdistribution hazard ratio: 0.81; 95% CI, 0.76-0.85; P<0.001) or transplant as a competing event (subdistribution hazard ratio: 0.67; 95% CI, 0.64-0.70; P<0.001). Conclusions A racial gap exists in PCI use among dialysis patients despite having comprehensive coverage with Medicare. These findings persisted despite accounting for demographic, clinical, socioeconomic factors, and death or transplant as competing events.

Association of Race and Poverty With Mortality Among Nursing Home Residents on Maintenance Dialysis

OBJECTIVES

The association of race, ethnicity, and socioeconomic factors with survival rates of nursing home (NH) residents with treated end-stage renal disease (ESRD) is unclear. We examined whether race/ethnicity, ZIP code-level, and individual-level indicators of poverty relate to mortality of NH residents on dialysis.

DESIGN

Retrospective cohort study.

PARTICIPANTS/SETTING

Using the United States Renal Data System database, we identified 56,194 nursing home residents initiated on maintenance dialysis from January 1, 2007 through December 31, 2013, followed until May 31, 2014.

MEASUREMENTS

We evaluated baseline characteristics of the NH cohort on dialysis, including race and ethnicity. We assessed the Medicare-Medicaid dual eligibility status as an indicator of individual-level poverty and ZIP code-level median household income (MHI) data. We conducted Cox regression analyses with all-cause mortality as the outcome variable, adjusted for clinical and sociodemographic factors including end-of-life preferences.

RESULTS

Adjusted Cox analysis showed a significantly lower risk of death among black vs nonblack NH residents [adjusted hazard ratio (AHR) 0.91, 95% confidence interval (CI) 0.89, 0.94]. Dual-eligibility status was significantly associated with lower risk of death compared to those with Medicare alone (AHR 0.80, 95% CI 0.78, 0.82). Compared to those in higher MHI quintile levels, NH ESRD patients in the lowest quintile were significantly associated with higher risk of death (AHR 1.09, 95% CI 1.06, 1.13).

CONCLUSIONS/IMPLICATIONS

Black and Hispanic NH residents on dialysis had an apparent survival advantage. This "survival paradox" occurs despite well-documented racial/ethnic disparities in ESRD and NH care and warrants further exploration that could generate new insights into means of improving survival of all NH residents on dialysis. Area-level indicator of poverty was independently associated with mortality, whereas dual-eligibility status for Medicare and Medicaid was associated with lower risk of death, which could be partly explained by improved access to care.

Pre-End-Stage Renal Disease Care and Early Survival among Incident Dialysis Patients in the US Military Health System

BACKGROUND

Previous reports showed an increased early mortality after chronic dialysis initiation among the end-stage renal disease (ESRD) population. We hypothesized that ESRD patients in the Military Health System (MHS) would have greater access to pre-ESRD care and hence better survival rates during this early high-risk period.

METHODS

In this retrospective cohort study, using the US Renal Data System database, we identified 1,256,640 patients initiated on chronic dialysis from January 2, 2004 through December 31, 2014, from which a bootstrap sample of 3,984 non-MHS incident dialysis patients were compared with 996 MHS patients. We assessed care by a nephrologist and dietitian, erythropoietin administration, and vascular access use at dialysis initiation as well as all-cause mortality as outcome variables.

RESULTS

MHS patients were significantly more likely to have had pre-ESRD nephrology care (adjusted OR [aOR] 2.9; 95% CI 2.3-3.7) and arteriovenous fistula used at dialysis initiation (aOR 2.2; 95% CI 1.7-2.7). Crude mortality rates peaked between the 4th and the 8th week for both cohorts but were reduced among MHS patients. The baseline adjusted Cox model showed significantly lower death rates among MHS vs. non-MHS patients at 6, 9, and 12 months. This survival advantage among MHS patients was attenuated after further adjustment for pre-ESRD nephrology care and dialysis vascular access.

CONCLUSIONS

MHS patients had improved survival within the first 12 months compared to the general ESRD population, which may be explained in part by differences in pre-ESRD nephrology care and vascular access types.

Impact of poverty and race on pre-end-stage renal disease care among dialysis patients in the United States

Background

Access to nephrology care prior to end-stage renal disease (ESRD) is significantly associated with lower rates of morbidity and mortality. We assessed the association of area-level and individual-level indicators of poverty and race/ethnicity on pre-ESRD care provided by nephrologists.

Methods

In this retrospective cohort study using the US Renal Data System database, we identified 739 537 patients initiated on maintenance dialysis from 1 January 2007 through 31 December 2012. We assessed the Medicare–Medicaid dual eligibility status as an indicator of individual-level poverty and ZIP code–level median household income (MHI) data obtained from the 2010 US census. We conducted multivariable logistic regression of pre-ESRD nephrology care as the outcome variable.

Results

Among patients in the lowest area-level MHI quintile, 61.28% received pre-ESRD nephrology care versus 67.68% among those in higher quintiles (P < 0.001). Similarly, the proportions of dual-eligible and nondual-eligible patients who had pre-ESRD nephrology care were 61.49 and 69.84%, respectively (P < 0.001). Patients in the lowest area-level MHI quintile were associated with significantly lower likelihood of pre-ESRD nephrology care (adjusted odds ratio [aOR] 0.86 [95% confidence interval (CI) 0.85–0.87]) compared with those in higher quintiles. Both African American (AA) and Hispanic patients were significantly less likely to have received pre-ESRD nephrology care [aOR 0.85 (95% CI 0.84–0.86) and aOR 0.72 (95% CI 0.71–0.74), respectively].

Conclusions

Individual- and area-level measures of poverty, AA race and Hispanic ethnicity were independently associated with a lower likelihood of pre-ESRD nephrology care. Efforts to improve pre-ESRD nephrology care may require focusing on the poor and minority groups.

Impact of Poverty and Health Care Insurance on Arteriovenous Fistula Use among Incident Hemodialysis Patients

BACKGROUND

The impact of socioeconomic factors on arteriovenous fistula (AVF) creation in hemodialysis (HD) patients is not well understood. We assessed the association of area and individual-level indicators of poverty and health care insurance on AVF use among incident end-stage renal disease (ESRD) patients initiated on HD.

METHODS

In this retrospective cohort study using the United States Renal Data System database, we identified 669,206 patients initiated on maintenance HD from January 1, 2007 through December 31, 2012. We assessed the Medicare-Medicaid dual-eligibility status as an indicator of individual-level poverty and ZIP code-level median household income (MHI) data obtained from the 2010 United States Census. We conducted logistic regression of AVF use at start of dialysis as the outcome variable.

RESULTS

The proportions of dual-eligible and non-dual-eligible patients who initiated HD with an AVF were 12.53 and 16.17%, respectively (p<0.001). Dual eligibility was associated with significantly lower likelihood of AVF use upon initiation of HD (adjusted odds ratio (aOR) 0.91; 95% CI 0.90-0.93). Patients in the lowest area-level MHI quintile had an aOR of 0.97 (95% CI 0.95-0.99) compared to those in higher quintile levels. However, dual eligibility and area-level MHI were not significant in patients with Veterans Affairs (VA) coverage.

CONCLUSIONS

Individual- and area-level measures of poverty were independently associated with a lower likelihood of AVF use at the start of HD, the only exception being patients with VA health care benefits. Efforts to improve incident AVF use may require focusing on pre-ESRD care to be successful.

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.

Effect of smoking on kidney transplant outcomes: analysis of the United States Renal Data System

BACKGROUND

We investigated the effect of smoking on postkidney transplant outcomes in the United States Renal Data System.

METHODS

In a retrospective cohort of 41,705 adult Medicare primary renal transplant recipients in the United States Renal Data System database transplanted from January 1, 2000, to June 30, 2006, and followed through October 31, 2006, we assessed Medicare claims for smoking. The association between renal allograft loss and death and smoking as a time-dependent variable was assessed with Cox nonproportional hazards regression.

RESULTS

Of 41,705 Medicare primary adult renal transplant patients, there were 9.9% patients who had evidence of prior smoking and 4.6% patients with new claims for smoking after transplant. Incident smoking (new onset smokers) occurred at a mean of 1.29±0.88 years after transplant. In the adjusted analysis, factors associated with new smoking included male gender, history of drug or alcohol use, history of chronic obstructive pulmonary disease, and later year of transplant. Compared with never smokers, incident smoking after transplant was associated with increased risk of death-censored allograft loss (adjusted hazard ratio [AHR] 1.46 [95% confidence interval {CI}: 1.19-1.79]; P<0.001) and death (AHR 2.32 [95% CI: 1.98-2.72]; P<0.001). In a sensitivity analysis excluding patients with history of chronic obstructive pulmonary disease, similar results were obtained with increased risk of death-censored allograft loss (AHR 1.43 [95% CI: 1.16-1.76]; P=0.001) and death (AHR 2.26 [95% CI: 1.91-2.66]; P<0.001).

DISCUSSION

Incident smoking was detrimental to graft and patient survival. Transplant programs should screen those at risk during transplant follow-up and have smoking cessation programs.

Poor outcomes in elderly kidney transplant recipients receiving alemtuzumab induction

INTRODUCTION

Alemtuzumab and rabbit antithymocyte globulin (rATG) are being used with increasing frequency as induction agents in kidney transplantation. Using the US Renal Data Base System, we analyzed the safety profile of these agents in the elderly.

METHODS

In a cohort of patients transplanted from January 2000 to July 2009 and followed through 2009, we assessed the effect of induction on allograft loss and death among elderly recipients. Recipients were censored at dates of allograft loss, death or the end of study. Independent associations between induction agents and allograft loss or death were examined using multivariate analysis with forward stepwise Cox regression.

RESULTS

Among 130,402 patients with first transplants, 14,907 were age 65 years or older. 4,466 (30%), 3,049 (20.5%), 1,501 (10.1%), and 999 (6.7%) were induced with thymoglobulin, basiliximab, daclizumab, and alemtuzumab, respectively. After adjusting for baseline differences, induction with alemtuzumab was associated with an increased risk of graft loss and death, with an adjusted hazard ratio (AHR) of 1.26 (95% CI 1.08-1.48). Risk was also present at other age cutoffs [age >60 (AHR 1.16; 95% CI 1.03-1.31; p = 0.014), age >70 (AHR 1.43; 95% CI 1.13-1.81; p = 0.003) and age >75 (AHR 1.68; 95% CI 1.07-2.63; p = 0.024)].

CONCLUSIONS

In the elderly, alemtuzumab is associated with an escalating risk of death and graft loss in recipients of kidney transplantations.

Outcomes associated with influenza vaccination in the first year after kidney transplantation

BACKGROUND AND OBJECTIVES

Influenza vaccination is recommended in all renal transplant recipients. However, immunosuppression in the early period post-transplant may attenuate the immunologic response to the vaccine. Additionally, it has been theorized that vaccination can induce an immune response that could trigger rejection episodes.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

In a retrospective cohort of 51,730 adult Medicare primary patients who were first transplanted from January 2000 to July 2006 and followed through October 2006, we assessed Medicare claims for influenza vaccination and influenza infections, respectively. Outcomes included allograft loss and death.

RESULTS

There were 9678 (18.7%) patients with claims for influenza vaccination in the first year post-transplant. Factors associated with vaccination included older age, diabetes, later year of transplant, and tacrolimus or mycophenolate at discharge. Vaccinations were less frequent among men, African Americans, highly sensitized patients, or those receiving induction immunosuppression or expanded criteria donor kidneys. Vaccination in the first year after transplant was associated with lower risk of subsequent allograft loss and death. Claims for influenza infection were reported in 310 (0.6%) patients and were not significantly associated with graft loss, although there was a trend toward death.

CONCLUSIONS

In the first year after renal transplantation, influenza vaccination was associated with a lower risk of subsequent allograft loss and death. Although this study cannot comment on formation of protective antibodies after vaccination, these data do not support withholding vaccination on the basis of concerns of adversely affecting allograft function.

Intensive blood-pressure control in hypertensive chronic kidney disease

BACKGROUND

In observational studies, the relationship between blood pressure and end-stage renal disease (ESRD) is direct and progressive. The burden of hypertension-related chronic kidney disease and ESRD is especially high among black patients. Yet few trials have tested whether intensive blood-pressure control retards the progression of chronic kidney disease among black patients.

METHODS

We randomly assigned 1094 black patients with hypertensive chronic kidney disease to receive either intensive or standard blood-pressure control. After completing the trial phase, patients were invited to enroll in a cohort phase in which the blood-pressure target was less than 130/80 mm Hg. The primary clinical outcome in the cohort phase was the progression of chronic kidney disease, which was defined as a doubling of the serum creatinine level, a diagnosis of ESRD, or death. Follow-up ranged from 8.8 to 12.2 years.

RESULTS

During the trial phase, the mean blood pressure was 130/78 mm Hg in the intensive-control group and 141/86 mm Hg in the standard-control group. During the cohort phase, corresponding mean blood pressures were 131/78 mm Hg and 134/78 mm Hg. In both phases, there was no significant between-group difference in the risk of the primary outcome (hazard ratio in the intensive-control group, 0.91; P=0.27). However, the effects differed according to the baseline level of proteinuria (P=0.02 for interaction), with a potential benefit in patients with a protein-to-creatinine ratio of more than 0.22 (hazard ratio, 0.73; P=0.01).

CONCLUSIONS

In overall analyses, intensive blood-pressure control had no effect on kidney disease progression. However, there may be differential effects of intensive blood-pressure control in patients with and those without baseline proteinuria. (Funded by the National Institute of Diabetes and Digestive and Kidney Diseases, the National Center on Minority Health and Health Disparities, and others.)

Arteriovenous fistulas among incident hemodialysis patients in Department of Defense and Veterans Affairs facilities

A higher proportion of patients initiate hemodialysis (HD) with an arteriovenous fistula (AVF) in countries with universal health care systems compared with the United States. Because federally sponsored national health care organizations in the United States, such as the Department of Veterans Affairs (DVA) and the Department of Defense (DoD), are similar to a universal health care model, we studied AVF use within these organizations. We used the US Renal Data System database to perform a cross-sectional analysis of patients who initiated HD between 2005 and 2006. Patients who received predialysis nephrology care had 10-fold greater odds of initiating dialysis with an AVF (adjusted odds ratio [aOR] 10.3; 95% confidence interval [CI] 9.6 to 11.1). DVA/DoD insurance also independently associated with initiating HD with an AVF (aOR 1.4; 95% CI 1.2 to 1.5). Fewer patients initiated HD at a DoD facility, but these patients were also approximately twice as likely to use an AVF (aOR 2.3; 95% CI 1.2 to 4.6). In conclusion, patients in DVA/DoD systems are significantly more likely to use an AVF at initiation of HD than patients with other insurance types, including Medicare. Further study of these federal systems may identify practices that could improve processes of care across health care systems to increase the number of patients who initiate HD with an AVF.

Incidence, predictors and outcomes of transplant renal artery stenosis after kidney transplantation: analysis of USRDS

OBJECTIVE

We analyzed the United States Renal Data System registry to study the risks, predictors, and outcomes of transplant renal artery stenosis (TRAS) in contemporary practice.

METHODS

The study sampled comprised adults with Medicare primary insurance who received kidney transplants in 2000-2005. We examined associations of recipient, donor and transplant factors with time-to-TRAS by the Kaplan-Meier method and multivariate Cox regression. Survival analysis methods were employed to estimate graft survival after TRAS, and to model TRAS as a time-dependent outcome predictor. Kaplan-Meier analysis was used to estimate time to allograft loss in patients who did or did not have an angioplasty procedure for TRAS.

RESULTS

There were 823 cases of TRAS among 41,867 transplant patients, with an incidence rate of 8.3 (95% CI 7.8-8.9) cases per 1,000 patient-years. Mean time to diagnosis of TRAS was 0.83 + or - 0.81 years after transplant. Factors associated with TRAS were older recipient and donor age, extended criteria donors, induction immunosuppression, delayed graft function, and ischemic heart disease. There was no association of TRAS with deceased donors, prolonged cold ischemia time, acute rejection or cytomegalovirus status. TRAS was associated with increased risk of graft loss (including death; adjusted hazard ratio 2.84, 95% CI 1.70-4.72). Among the 823 patients with TRAS, 145 (17.6%) underwent angioplasty. Graft survival after TRAS was not significantly different in patients treated with angioplasty compared to those without angioplasty.

CONCLUSIONS

TRAS is an important complication that predicts adverse patient and graft outcomes. Treatment strategies for TRAS warrant prospective investigation in clinical trials.

Incidence, predictors and associated outcomes of rhabdomyolysis after kidney transplantation

BACKGROUND

There are several case reports of rhabdomyolysis (RM) in renal transplant recipients, but the actual incidence of this complication is not known. Most of the reported cases have been attributed to drug-drug interactions with calcineurin inhibitors, with the majority of interactions reported between cyclosporine and 3-hydroxy-3-methylglutaryl-coenzyme A reductase inhibitors (statins). Pharmacokinetic studies have demonstrated that cyclosporine increases statin drug levels, presumably via competitive inhibition of cytochrome P450 3A4.

METHODS

In a retrospective cohort of 20 366 adult Medicare primary renal transplant recipients in the USRDS database transplanted from 1 January 2003 to 31 July 2005 and followed through 31 December 2005, we assessed Medicare claims for RM and dyslipidaemia (HPL), which was used as a surrogate for statin use.

RESULTS

The incidence rate of RM post-transplant for the study period was 1.4 (95% CI 1.1-1.8) per 1000 person-years. By Cox regression analysis, cyclosporine (versus tacrolimus) use [AHR 2.36 (95% CI 1.23-4.35); P = 0.006] and black race [AHR 2.33 (95% CI 1.30-4.17); P = 0.005] were associated with RM. By Cox non-proportional hazards regression, RM was associated with graft loss (including death) [AHR 2.84 (95% CI 1.70-4.72); P < 0.001].

CONCLUSIONS

RM is a rare complication after renal transplantation and is significantly associated with allograft loss (including death). RM is significantly more likely to occur with cyclosporine (versus tacrolimus)-based immunosuppression and possibly in persons of black race. Increased surveillance for RM is warranted in these at-risk patients.

The comprehensive dialysis study (CDS): a USRDS special study

BACKGROUND AND OBJECTIVES

The Comprehensive Dialysis Study (CDS) aimed to understand factors contributing to physical, functional, and nutritional health status among patients starting dialysis.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

A phone interview survey was conducted with patients from a geographically stratified national random sample of dialysis units, and quarterly serum samples were obtained for patients at a preidentified subset of units. The phone survey collected standardized measures of physical activity, employment and disability status, perceived health and well-being, and dietary intake. Serum samples were obtained to measure prealbumin, albumin, creatinine, normalized protein catabolic rate, and C-reactive protein. To comply with restrictions required under the Health Insurance Portability and Accountability Act (HIPAA), dialysis unit personnel could not participate in any research-related activities.

RESULTS

Overall participation rate was 18.5%. One thousand six hundred forty-six patients affiliated with 295 dialysis units completed the phone survey; 361 patients affiliated with 68 dialysis units also completed a dietary intake survey, with 269 providing serum samples. Despite challenges in the design and implementation of CDS, the population was diverse and results should be generalizable.

CONCLUSIONS

Constraints within the dialysis industry and HIPAA requirements render the assembly of nationally representative cohorts extremely difficult. Nevertheless, the CDS represents the largest cohort of incident dialysis patients containing detailed information on self-reported physical activity and dietary intake and is one of few cohorts simultaneously measuring laboratory proxies of nutrition and inflammatory status. Data from CDS can be used to inform the design of interventions addressing several conditions that affect longevity and health status in ESRD.

Incidence, predictors, and associated outcomes of prostatism after kidney transplantation

BACKGROUND AND OBJECTIVES

Renal transplantation is increasingly performed in elderly patients, and the incidence of benign prostatic hyperplasia (BPH) increases with age. Anuric males on dialysis may have occult BPH and not develop obstructive symptoms until urine flow is restored after transplantation. If left untreated, BPH poses a risk for numerous complications, including acute urinary retention (AUR), recurrent urinary tract infections (UTI), and renal failure. The authors hypothesized that incident BPH after renal transplantation would adversely affect allograft survival.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

Medicare claims for BPH, AUR, UTI, and prostate resection procedures (transurethral resection of the prostate; TURP) were assessed in a retrospective cohort of 23,622 adult male Medicare primary renal transplant recipients in the United States Renal Data System database who received transplants from 1 January 2000 to 31 July 2005 and followed through 31 December 2005.

RESULTS

The 3-yr incidence of BPH post-transplant was 9.7%. The incidences of AUR, UTI, and TURP after BPH diagnosis (up to 3 yr posttransplant) were 10.3%, 6.5%, and 7.3% respectively, and each was significantly associated with BPH. Cox regression analysis showed that recipient age per year, later year of transplant, and dialysis vintage were associated with incident BPH. Using Cox nonproportional hazards regression, BPH was significantly associated with renal allograft loss (including death).

CONCLUSIONS

BPH is common in males after renal transplant and is independently associated with AUR, UTI, and graft loss. It is unknown whether treatment of BPH, either medical or surgical, attenuates these risks.

Long-term effects of renin-angiotensin system-blocking therapy and a low blood pressure goal on progression of hypertensive chronic kidney disease in African Americans

BACKGROUND

Antihypertensive drugs that block the renin-angiotensin system (angiotensin-converting enzyme inhibitors [ACEIs] or angiotensin receptor blockers) are recommended for patients with chronic kidney disease (CKD). A low blood pressure (BP) goal (BP, <130/80 mm Hg) is also recommended. The objective of this study was to determine the long-term effects of currently recommended BP therapy in 1094 African Americans with hypertensive CKD.

METHODS

Multicenter cohort study following a randomized trial. Participants were 1094 African Americans with hypertensive renal disease (glomerular filtration rate, 20-65 mL/min/1.73 m2). Following a 3x2-factorial trial (1995-2001) that tested 3 drugs used as initial antihypertensive therapy (ACEIs, calcium channel blockers, and beta-blockers) and 2 levels of BP control (usual and low), we conducted a cohort study (2002-2007) in which participants were treated with ACEIs to a BP lower than 130/80 mm Hg. The outcome measures were a composite of doubling of the serum creatinine level, end-stage renal disease, or death.

RESULTS

During each year of the cohort study, the annual use of an ACEI or an angiotensin receptor blocker ranged from 83.7% to 89.0% (vs 38.5% to 49.8% during the trial). The mean BP in the cohort study was 133/78 mm Hg (vs 136/82 mm Hg in the trial). Overall, 567 participants experienced the primary outcome; the 10-year cumulative incidence rate was 53.9%. Of 576 participants with at least 7 years of follow-up, 33.5% experienced a slow decline in kidney function (mean annual decline in the estimated glomerular filtration rate, <1 mL/min/1.73 m2).

CONCLUSION

Despite the benefits of renin-angiotensin system-blocking therapy on CKD progression, most African Americans with hypertensive CKD who are treated with currently recommended BP therapy continue to progress during the long term.

Assessment of racial disparities in chronic kidney disease stage 3 and 4 care in the department of defense health system

BACKGROUND AND OBJECTIVES

Racial disparities in provision of healthcare are widespread in the United States but have not been specifically assessed in provision of chronic kidney disease (CKD) care.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

We conducted a retrospective cohort study of the clinical database used in a Department of Defense (DOD) medical system. Beneficiaries studied were DOD-eligible beneficiaries with CKD stage 3 (n = 7729) and 4 (n = 589) using the modified Modification of Diet in Renal Disease (MDRD)-estimated GFR formula but requiring manual correction for Black race. Compliance with selected Kidney Disease Outcomes Quality Initiative (KDOQI) CKD recommended targets (monitoring of recommended laboratory data, prescription of recommended medications, and referral to nephrology) was assessed over a 12-mo period, stratified by CKD stage. Logistic regression analysis was used to assess whether race (White, Black, or other) was independently associated with provider compliance with targets, adjusted for demographic factors and burden of comorbid conditions.

RESULTS

Among the targets, only monitoring of LDL cholesterol was significantly less common among Blacks. For all other measures, compliance was either not significantly different or significantly higher for Black compared with White beneficiaries. However, patients categorized as "Other" race were in general less likely to achieve targets than Whites, and at stage 3 CKD significantly less likely to achieve targets for monitoring of phosphorous, hemoglobin, and vitamin D.

CONCLUSIONS

In the DOD health system, provider compliance with selected CKD stage 3 and 4 targets was not significantly lower for Black beneficiaries than for Whites, with the exception of LDL cholesterol monitoring. Patients classified as Other race were generally less likely to achieve targets than Whites, in some patients significantly so.

Risk factors for hospitalization for bacterial or viral infection in renal transplant recipients--an analysis of USRDS data

We previously showed that children are more likely to develop viral infections post-kidney transplant while adults are more likely to develop bacterial infections. In this study we determined the overall risk factors for hospitalization with either a bacterial (HBI) or a viral infection (HVI). We analyzed data from 28 924 United States Renal Data System (USRDS) Medicare primary renal transplant recipients from January 1996 to July 2000, for adjusted hazard ratio (AHR) for HBI or HVI in the first 3 years posttransplant. For HVI, significantly higher AHR was seen with (a) recipient age <18 years (AHR 1.57, 95% CI = 1.02, 2.42), (b) donor CMV positive (AHR 1.72, 95% CI = 1.34, 2.19). For HBI, significantly higher AHR was seen with (i) delayed graft function (AHR 1.28, 95% CI = 1.076, 1.518), (ii) primary renal diagnosis chronic pyelonephritis (AHR 1.71, 95% CI = 1.18, 2.49); (iii) associated pretransplant diabetes (AHR 1.80, 95% CI = 1.53, 2.12); (iv) female gender AHR 1.63, 95% CI = 1.41, 1.88). Lower AHR for HVI was seen in CMV-positive recipients and for HBI with more recent year of transplant. Other covariates did not impact significantly in either HVI or HBI.

Longitudinal study of racial and ethnic differences in developing end-stage renal disease among aged medicare beneficiaries

Diabetes and hypertension are the leading causes of renal failure. This study investigated racial differences in developing ESRD by participants' diabetes and hypertension status. This longitudinal study included 1,306,825 Medicare beneficiaries who were aged > or =66 yr at the study start and followed up to 10 yr from January 1, 1993, for the development of ESRD or death. During the 10 yr, 0.93 patients per 100 received ESRD treatment. After adjustment for age and gender, among patients with diabetes, black patients were 2.4 to 2.7 times and other races/ethnicities 1.6 to 1.7 times more likely than white patients to develop ESRD. Among hypertensive patients, black patients were 2.5 to 2.9 and others 1.7 to 1.8 times more likely than white patients to develop ESRD. Among patients with neither diabetes nor hypertension, black patients were 3.5 and others 2.0 times more likely. Black men with diabetes were 1.9 to 2.1 and women 2.5 to 3.4 times more likely than their white counterparts to develop ESRD. Hypertensive black men were 2.1 to 2.2 and women 2.8 to 3.6 times more likely to develop ESRD. The same findings were noted in women of other races/ethnicities. Compared with white counterparts, mortality was higher for black patients in all cohorts but lower among patients with ESRD. Although they are leading causes for renal failure, diabetes and hypertension do not cause racial differences in developing ESRD. Minority women especially are at greater risk for ESRD than white women. Further studies are needed to determine whether earlier initiation of dialysis is a factor in higher ESRD incidence among minorities.

Effects of Urinary Tract Infection on Outcomes after Renal Transplantation in Children

Urinary tract infection (UTI) is the most common infection after kidney transplantation. A previous analysis showed that late (>6 mo after transplantation) UTI is associated with earlier graft loss in adults. It was hypothesized that children who are younger than 18 yr would be at higher risk to develop UTI and develop graft loss after both early and late UTI. The US Renal Data System database was analyzed from 1996 to 2000 for Medicare claims (composite of inpatient and outpatient) for UTI up to 36 mo after transplantation. SPSS software and Cox regression models were used to determine association of UTI and age after adjustment for covariates. Early UTI was defined as occurring <6 mo after transplantation, and late UTI was defined as occurring > or =6 mo after transplantation. The risk for graft loss after early UTI was elevated in all children (adjusted hazard ratio [AHR] 5.47; 95% confidence interval [CI] 1.93 to 15.4; P < 0.001) but not after late UTI (AHR 2.09; 95% CI 0.56 to 7.80; P = 0.27). Risk for posttransplantation death was not increased significantly after either early UTI (AHR 1.23; 95% CI 0.37 to 4.08) or late UTI (relative risk 2.22; 95% CI 0.90 to 5.44). Boys aged 2 to 5 (versus age 13 to <18 years) were at significantly higher risk for UTI. In girls, only those in the youngest age category (0 to 1) had higher risk for UTI. Children are at greater risk for graft loss after early but not necessarily late UTI. UTI was not an independent predictor of death in this population.

Risk factors for Mycobacterium tuberculosis in US chronic dialysis patients

BACKGROUND

End-stage renal disease is known to disrupt the cell-mediated immune response that is responsible for the killing of intracellular organisms such as Mycobacterium tuberculosis. Risk factors that contribute to the development of tuberculosis (TB) disease in the US dialysis population have not been studied on a large scale.

METHODS

A retrospective cohort study of TB disease in 272,024 patients in the US Renal Data System initiated on dialysis therapy between 1 April 1995 and 31 December 1999 with Medicare or Medicaid as primary payer were analysed. A total of 21 risk factors were analysed.

RESULTS

Among the US population studied, there is a 1.2 and 1.6% cumulative incidence of TB in patients undergoing either peritoneal or haemodialysis, respectively. Ten risk factors for TB that proved to be statistically significant included advanced age (P<0.001), unemployment (P<0.001), Medicaid insurance (P<0.001), reduced body mass index (P<0.001), decreased serum albumin (P<0.001), haemodialysis (P=0.019), both Asian (P=0.010) and Native American (P=0.020) race, ischaemic heart disease (P=0.032), smoking (P=0.010), illicit drug use (P=0.018) and anaemia (P=0.028). TB was independently associated with increased mortality, adjusted hazard ratio (AHR) 1.42 (95% CI 1.18-1.70, P<0.001).

CONCLUSIONS

The prevalence of TB disease in the US dialysis population is low compared with worldwide rates; however, the disease is associated with increased mortality. Of the 10 significant risk factors identified, five are potentially modifiable.

Dementia as a predictor of mortality in dialysis patients

The life expectancy of patients who have dementia and are initiated on dialysis in the United States has not been described in the medical literature. A retrospective cohort study was conducted of 272,024 Medicare/Medicaid primary patients in the US Renal Data System who were started on ESRD therapy between April 1, 1995, and December 31, 1999, and followed through December 31, 2001. Cox regression was used to calculate adjusted hazard ratios for risk for death after initiation of dialysis for patients whose dementia was diagnosed before the initiation of dialysis as shown by Medicare claims. The average time to death for patients with dementia was 1.09 versus 2.7 yr (P < 0.001) with an adjusted hazard ratio of 1.87 (95% confidence interval 1.77 to 1.98). The 2-yr survival for patients with dementia was 24 versus 66% for patients without dementia (P < 0.001 via log rank test). Dementia that is diagnosed before initiation on dialysis is an independent risk factor for subsequent death. Such patients should be considered for time-limited trials of dialysis and careful discussion in choosing whether to pursue initiation of dialysis or palliative care.

Infection frequency and profile in different age groups of kidney transplant recipients

BACKGROUND

Older transplant recipients have been shown to be at greater risk for infectious death than younger adults, but no study to date has looked at relative risk of infection and infection profile differences for children versus adults, which may be very different from one another.

METHODS

Data from primary Medicare renal transplant recipients between 1991 and 1998 (n=64,751), as reported in the United States Renal Data System (USRDS), were analyzed for Medicare claims (both inpatient and outpatient) for infection and type of infection in the first year posttransplant. Cox regression was used to model adjusted hazard ratios (AHR) for infection.

RESULTS

Total infections among renal transplant recipients increased significantly in more recent years. Patients transplanted in or after 1995 had a significantly higher adjusted risk for infection compared to those transplanted earlier (AHR 1.34, 95% CI=1.29-1.39). Older adults > or = 51 years of age had the highest percentage of experiencing infection, as compared to adults between 18-50 years and children < or = 17 years (P<0.001). Children were at highest risk of viral infection prior to 1995 but at lowest risk of viral infection after 1995, whereas elderly adults were at highest risk of bacterial infection throughout the study. Children experienced more claims for viral infections, whereas older transplant recipients experienced more claims for bacterial infections.

CONCLUSIONS

The two extremes of transplant recipient age display very different risks for infection claim frequency and profile.

Myeloma, Hodgkin disease, and lymphoid leukemia after renal transplantation: characteristics, risk factors and prognosis

BACKGROUND

Hodgkin disease and myeloma were recently included in the classification of posttransplant lymphoproliferative disorder (PTLD). However, because their incidence is low, not much is known about their particular features.

METHODS

The incidence, characteristics, risk, and prognostic factors of myeloma, Hodgkin disease, and lymphoid leukemia using the United States Renal Data System from 1991 to 2000 among 66,159 Medicare patients were analyzed.

RESULTS

In all, 1,169 recipients developed a lymphoid disease: 823 (1.2%) non-Hodgkin's lymphomas (NHL), 160 (0.24%) myelomas, 60 (0.1%) Hodgkin lymphomas, and 126 (0.2%) lymphoid leukemias. Older age was associated with an increased risk of myeloma and leukemia. The incidence of hepatitis C virus infection was higher in recipients with myeloma (6.9 vs. 3.9%, P=0.05). Induction therapy was associated with a greater risk of myeloma and leukemia, but not Hodgkin disease. Azathioprine was associated with a lower risk of myeloma, and tacrolimus with a lower risk of Hodgkin disease. According to the type of malignancy, ten-year survival rates were significantly different: 42, 26, 55 and 39% respectively for NHL, myeloma, Hodgkin disease, and leukemia.

CONCLUSION

These results support specific features and risk factors related to the occurrence of each type of lymphoid-proliferation and suggest for the first time a possible association between hepatitis C virus and myeloma in kidney transplant recipients.

Differing effects of antihypertensive drugs on the incidence of diabetes mellitus among patients with hypertensive kidney disease

BACKGROUND

The African American Study of Kidney Disease and Hypertension was a multicenter trial of African Americans with hypertensive kidney disease randomized to an angiotensin-converting enzyme inhibitor (ramipril), a beta-blocker (metoprolol succinate), or a calcium channel blocker (amlodipine besylate). We compared the incidence of type 2 diabetes mellitus (DM) and the composite outcome of impaired fasting glucose or DM (IFG/DM) for the African American Study of Kidney Disease and Hypertension interventions.

METHODS

Cox regression models were used to evaluate (post hoc) the association of the randomized interventions and the relative risk (RR) of DM and IFG/DM and to assess the RR of DM and IFG/DM by several prerandomization characteristics.

RESULTS

Among 1017 participants, 147 (14.5%) developed DM; 333 (42.9%) of 776 participants developed IFG/DM. Respective DM event rates were 2.8%, 4.4%, and 4.5% per patient-year in the ramipril-, amlodipine-, and metoprolol-treated groups. The RRs of DM with ramipril treatment were 0.53 (P = .001) compared with metoprolol treatment and 0.49 (P = .003) compared with amlodipine treatment. Respective IFG/DM event rates were 11.3%, 13.3%, and 15.8% per patient-year in the ramipril-, amlodipine-, and metoprolol-treated groups. The RRs of IFG/DM with ramipril treatment were 0.64 (P<.001) compared with metoprolol treatment and 0.76 (P = .09) compared with amlodipine treatment. The RRs of DM and IFG/DM with amlodipine treatment compared with metoprolol treatment were 1.07 (P = .76) and 0.84 (P = .26), respectively.

CONCLUSION

Ramipril treatment was associated with a significantly lower risk of DM in African Americans with hypertensive kidney disease than amlodipine or metoprolol treatment.

Unraveling the racial disparities associated with kidney disease

In the United States, chronic kidney disease (CKD), and in particular end-stage renal disease (ESRD), represent a growing problem. Many other countries also have an increasing number of ESRD cases. Racial/ethnic disparities have been documented globally in the prevalence, incidence, and treatment of CKD, most extensively in the United States, but also in the United Kingdom, Australia, and New Zealand, among others. In many circumstances, these disparities are of a negative nature, that is, certain racial/ethnic groups fare worse than their white counterparts with respect to the treatment or outcome of CKD. However, in a few circumstances, they are of a positive nature, such as the survival advantage seen in minorities with ESRD compared with whites. The reasons for racial disparities in the prevalence, incidence, and treatment of CKD are not fully understood, although they are explained partly by coexisting medical conditions and modifiable risk factors, such as socioeconomic, lifestyle, and cultural. It is likely, however, that the complete picture incorporates a complex interaction between these sociocultural, genetic, and environmental factors. In a global society that prides itself on a high level of sensitivity and equality, there is an ethical and moral imperative to address the continuing racial/ethnic disparities in CKD and many of the factors underlying this epidemic. We review data highlighting the racial/ethnic disparities that exist in the incidence and treatment of CKD, with particular emphasis on ESRD. A better understanding of both the negative and positive racial/ethnic disparities may yield important insights, which can inform future research strategies and improve health outcomes for all patients afflicted with CKD.

New-Onset Gout after Kidney Transplantation: Incidence, Risk Factors and Implications

BACKGROUND

Although cyclosporine use has been associated with an increased risk of new-onset gout after renal transplantation, the incidence and risk factors for new-onset gout have not been reported in the era of modern immunosuppression.

METHODS

We conducted a retrospective cohort study of Medicare primary renal transplant patients reported in the United States Renal Data System (USRDS), using Medicare claims data to determine the incidence of new-onset gout. Cox regression analysis was used to calculate adjusted hazard ratios (AHR) for cyclosporine (including separate analysis of Neoral) compared directly with tacrolimus, for the risk of new-onset gout, adjusted for baseline demographic factors and posttransplant renal function.

RESULTS

The cumulative incidence of new-onset gout was 7.6% at 3 years posttransplant. The following factors were independently associated with an increased risk of new-onset gout: use of Neoral (vs. tacrolimus, AHR 1.25, 95% CI 1.07-1.47) at discharge, recipient male sex (AHR 1.44, 95% CI 1.25-1.67), older age, higher body mass index, and more recent year of transplant. No other immunosuppressive medications were associated with new-onset gout. Diabetes was associated with a significantly lower risk of new-onset gout. The development of new-onset gout was independently associated with decreased patient survival (AHR 1.26, 95% CI 1.08-1.47) as well as death-censored graft survival.

CONCLUSIONS

Cyclosporine is an independent risk factor for new-onset gout after transplantation. The incidence of new-onset gout appears to be increasing even while the use of cyclosporine is decreasing, and the development of new-onset gout was an independent predictor for death and graft loss in this population.

Thrombotic microangiopathy in United States long-term dialysis patients

BACKGROUND

The incidence, risk factors, recurrence rates and prognosis of thrombotic microangiopathy (TMA) among long-term dialysis patients in the United States have not been previously described in a national population.

METHODS

272 024 Medicare primary patients in the United States Renal Data System (USRDS) initiated on end-stage renal disease (ESRD) therapy between 1 April 1995 and 31 December 1999 with Medicare as primary payer were analysed in a retrospective cohort study of USRDS of TMA. Cox regression was used to calculate adjusted hazard ratios (AHR) for risk of TMA and risk of death after TMA.

RESULTS

The incidence of TMA in the first year of dialysis was 0.5% overall. Among patients with renal failure due to haemolytic uraemic syndrome (HUS), the incidence of TMA was highest in the first year of dialysis (HUS, 11.3% first year, 4.5% per year thereafter), while among patients without HUS the incidence of TMA was much lower and more constant over time (0.3% per year). In Cox regression analysis, independent risk factors for TMA were renal failure due to HUS (adjusted hazard ratio (AHR) 179, 95% CI 95-338), paediatric age (<or=18 years vs older, AHR 2.59, 95% CI 1.48-4.55), female gender (AHR 1.99, 95% CI 1.43-2.78), and systemic lupus erythematosus (SLE, AHR 3.66, 95% CI 1.49-8.51). One-year survival after TMA was poor at 58% (AHR for mortality 2.04, 95% CI 1.23-3.38).

CONCLUSIONS

TMA is an uncommon cause of hospitalization after dialysis, but does recur in patients with HUS at a substantial rate. Younger age and SLE were risk factors for new onset TMA, which was associated with poor survival. Vigilant monitoring of select patients with HUS-related ESRD and higher-risk patients with SLE is warranted in the dialysis population.

Differing Manifestations of Hepatitis C and Tacrolimus on Hospitalized Diabetes Mellitus Occurring after Kidney Transplantation

PURPOSE

Previous studies suggest the association of recipient hepatitis C seropositivity (HCV+) and use of tacrolimus (TAC) with post-transplant diabetes mellitus (PTDM) may differ by manifestations of type I or type II diabetes, but this has not been assessed in the era of current immunosuppression.

METHODS

We performed a retrospective cohort study of 10,342 Medicare primary renal transplantation recipients without evidence of diabetes at the time of listing in the United States Renal Data System between January 1, 1998 and July 31, 2000, followed until December 31, 2000. Outcomes were hospitalizations for a primary diagnosis of diabetic ketoacidosis (DKA) or hyperglycemic hyperosmolar syndrome (HHS). Cox regression analysis was used to calculate adjusted hazard ratios (AHR) for time to DKA or HHS, stratified by diabetes status at the time of transplant.

RESULTS

In Cox regression analysis, use of TAC at discharge was independently associated with shorter time to DKA (AHR, 1.88; 95% CI, 1.05-3.37, p=0.034) but not HHS. In contrast, recipient HCV+ was independently associated with shorter time to HHS (AHR, 3.90; 1.59-9.60, p=.003), but not DKA. There was no interaction between TAC and HCV+ for either outcome.

CONCLUSION

These results confirm earlier findings that TAC and HCV+ may mediate the risk of PTDM through different mechanisms, even in the modern era.

Blood Pressure Control, Drug Therapy, and Kidney Disease

The African American Study of Kidney Disease and Hypertension examined the effect on renal function decline of 2 blood pressure (BP) goals (low mean arterial pressure [MAP] ≤92 versus usual MAP 102 to 107 mm Hg) and 3 antihypertensives (ramipril versus amlodipine versus metoprolol). We previously reported that in all drug groups combined the BP intervention had similar effects on the primary outcome of glomerular filtration rate (GFR) slope or the main secondary clinical composite outcome of end-stage renal disease (ESRD), death, or GFR decline by 50% or 25 mL/min per 1.73 m 2 . This report examines the effect of the BP intervention separately in the 3 drug groups. The BP effect was similar among the drug groups for either GFR slope or the main clinical composite. However, the BP effect differed significantly among the drug groups for the composite of ESRD or death ( P =0.035) and ESRD alone ( P =0.021). Higher event rates for amlodipine patients assigned to the usual BP goal (0.087 per patient-year for ESRD or death and 0.064 per patient-year for ESRD) were seen compared with the remaining groups of the factorial design (range, 0.041 to 0.050 for ESRD or death; and range, 0.027 to 0.036 for ESRD). The low BP goal was associated with reduced risk of ESRD or death (risk reduction 51%; 95% confidence interval, 13% to 73%) and ESRD (54%; 8% to 77%) for amlodipine patients, but not for patients assigned to the other drug groups. These secondary analyses suggest a benefit of the low BP goal among patients assigned to amlodipine, but they must be interpreted cautiously.

Impact of diabetes and hepatitis after kidney transplantation on patients who are affected by hepatitis C virus

Complications associated with use of donor hepatitis C-positive kidneys (DHCV+) have been attributed primarily to posttransplantation liver disease (as a result of hepatitis C disease). The role of posttransplantation diabetes has not been explored in this setting. With the use of the United States Renal Data System database, 28,942 Medicare KT recipients were studied from January 1, 1996, through July 31, 2000. Cox proportional hazards regression models were used to calculate adjusted hazard ratios (AHR) for the association of sero-pairs for HCV (D+/R-, D+/R+, D-/R+ and D-/R-) with Medicare claims for de novo posttransplantation HCV and posttransplantation diabetes. The peak risk for posttransplantation HCV was in the first 6 mo after transplantation. The incidence of posttransplantation HCV after transplantation was 9.1% in D+/R-, 6.3% in D+/R+, 2.4% in D-/R+, and 0.2% in D-/R-. The incidence of posttransplantation diabetes after transplantation also peaked early and was 43.8% in D+/R-, 46.6% in D+/R+, 32.3% in D-/R+, and 25.4% in D-/R-. Associations for both complications were significant in adjusted analysis (Cox regression). Both posttransplantation HCV (AHR, 3.36; 95% confidence interval, 2.44 to 4.61) and posttransplantation diabetes (AHR, 1.81; 95% confidence interval, 1.54 to 2.11) were independently associated with an increased risk of death, but posttransplantation diabetes accounted for more years of life lost, particularly among recipients of DHCV+ kidneys. Posttransplantation diabetes may contribute substantially to the increased risk of death associated with use of DHCV+ kidneys and accounts for more years of life lost than posttransplantation HCV. Because HCV infection acquired after transplantation is so difficult to treat, methods that have been shown to reduce viral transmission warrant renewed attention.

Late urinary tract infection after renal transplantation in the United States

BACKGROUND

Although urinary tract infection (UTI) occurring late after renal transplantation has been considered "benign," this has not been confirmed in a national population of renal transplant recipients.

METHODS

We conducted a retrospective cohort study of 28,942 Medicare primary renal transplant recipients in the United States Renal Data System (USRDS) database from January 1, 1996, through July 31, 2000, assessing Medicare claims for UTI occurring later than 6 months after transplantation based on International Classification of Diseases, 9th Revision (ICD-9), codes and using Cox regression to calculate adjusted hazard ratios (AHRs) for time to death and graft loss (censored for death), respectively.

RESULTS

The cumulative incidence of UTI during the first 6 months after renal transplantation was 17% (equivalent for both men and women), and at 3 years was 60% for women and 47% for men (P < 0.001 in Cox regression analysis). Late UTI was significantly associated with an increased risk of subsequent death in Cox regression analysis (P < 0.001; AHR, 2.93; 95% confidence interval [CI], 2.22, 3.85); and AHR for graft loss was 1.85 (95% CI, 1.29, 2.64). The association of UTI with death persisted after adjusting for cardiac and other infectious complications, and regardless of whether UTI was assessed as a composite of outpatient/inpatient claims, primary hospitalized UTI, or solely outpatient UTI.

CONCLUSION

Whether due to a direct effect or as a marker for serious underlying illness, UTI occurring late after renal transplantation, as coded by clinicians in the United States, does not portend a benign outcome.

β-Blocker Use in Long-term Dialysis Patients

BACKGROUND

beta-Blockers have been shown to be beneficial in the treatment and prevention of heart failure (HF) in the general population, but they have not been assessed for their association with nonfatal HF in a nationally representative population of long-term dialysis patients.

METHODS

We conducted a retrospective cohort study of 2550 patients enrolled in the US Renal Data System (USRDS) Wave 2 who were Medicare eligible at the start of the study. Analysis was stratified by the presence or absence of a known diagnosis of HF, and patients followed up until December 31, 2000. Cox regression analysis, including propensity scores, was used to model adjusted hazard ratios for beta-blocker use (assessed separately by cardioselective activity and lipid solubility) with time to the first Medicare institutional claim for HF, cardiovascular-related death, or death from any cause.

RESULTS

In patients without a previous history of HF, beta-blocker use was significantly associated with a lower adjusted risk of HF (adjusted hazard ratio, 0.69; 95% confidence interval, 0.52-0.91; P=.008), with a similar reduction in risk of cardiac-related and all-cause death. beta-Blocker use had no statistically significant associations with outcomes in patients with previous HF.

CONCLUSIONS

In dialysis patients without a previous documented history of HF, beta-blocker use was associated with a lower risk of new HF, cardiovascular death, and death from any cause. No such associations were seen for dialysis patients with a previous history of HF. These results are hypothesis generating only and should be confirmed in randomized trials.

The impact of transplantation with deceased donor hepatitis c-positive kidneys on survival in wait-listed long-term dialysis patients

Whether transplantation of deceased donor kidney allografts from donors with antibodies against hepatitis C virus (HCV) confers a survival advantage compared with remaining on the kidney transplant waiting list is not yet known. We studied 38,270 USRDS Medicare beneficiaries awaiting kidney transplantation who presented with end-stage renal disease from April 1, 1995 to July 31, 2000. Cox regression was used to compare the adjusted hazard ratios for death among recipients of kidneys from deceased donors, and donors with antibodies against hepatitis C (DHCV+), controlling for demographics and comorbidities. In comparison to staying on the waiting list, transplantation from DHCV+ was associated with improved survival among all patients (adjusted hazard ratio for death 0.76, 95% CI 0.60, 0.96). Of patients receiving DHCV+ kidneys, 52% were themselves hepatitis C antibody positive (HCV+), so outcomes associated with use of these grafts may have particular implications for HCV+ transplant candidates. Recommendations for use of DHCV+ kidneys may require analysis of data not currently collected from either dialysis or transplant patients. However, transplantation of DHCV+ kidneys is associated with improved patient survival compared to remaining wait-listed and dialysis dependent.

Body mass index, dialysis modality, and survival: analysis of the United States Renal Data System Dialysis Morbidity and Mortality Wave II Study

BACKGROUND

The impact of obesity on survival in end-stage renal disease (ESRD) patients as related to dialysis modality (i.e., a direct comparison of hemodialysis with peritoneal dialysis) has not been assessed adjusting for differences in medication use, follow-up > or =2 years, or accounting for changes in dialysis modality.

METHODS

We performed a retrospective cohort study of the United States Renal Data System (USRDS) Dialysis Morbidity and Mortality Wave II Study (DMMS) patients who started dialysis in 1996, and were followed until October 31 2001. Cox regression analysis was used to model adjusted hazard ratios (AHR) for mortality for categories of body mass index (BMI), both as quartiles and as > or =30 kg/m2 vs. lower. Because such a large proportion of peritoneal dialysis patients changed to hemodialysis during the study period (45.5%), a sensitivity analysis was performed calculating survival time both censoring and not censoring on the date of change from peritoneal dialysis to hemodialysis.

RESULTS

There were 1675 hemodialysis and 1662 peritoneal dialysis patients. Among hemodialysis patients, 5-year survival for patients with BMI > or =30 kg/m2 was 39.8% vs. 32.3% for lower BMI (P < 0.01 by log-rank test). Among peritoneal dialysis patients, 5-year survival for patients with BMI >/=30 kg/m2 was 38.7% vs. 40.4% for lower BMI (P > 0.05 by log-rank test). In adjusted analysis, BMI > or = 30 kg/m2 was associated with improved survival in hemodialysis patients (AHR 0.89; 95% CI 0.81, 0.99; P= 0.042) but not peritoneal dialysis patients (AHR = 0.99; 95% CI, 0.86, 1.15; P= 0.89). Results were not different on censoring of change from peritoneal dialysis to hemodialysis.

CONCLUSION

We conclude that any survival advantage associated with obesity among chronic dialysis patients is significantly less likely for peritoneal dialysis patients, compared to hemodialysis patients.