Hospitalized congestive heart failure after renal transplantation in the United States

Arteriovenous fistula for haemodialysis as a predictor of de novo heart failure in kidney transplant recipients

Background

The haemodynamic effects of a functioning haemodialysis arteriovenous fistula (AVF) can cause or exacerbate heart failure (HF). We investigated whether the presence of an AVF at the time of kidney transplant (KT) is associated with de novo HF.

Methods

This was an observational cohort study including adult patients who received a KT in the West of Scotland between 2010 and 2020. We evaluated the risk and associations of pretransplant factors with de novo HF, alone and as a composite cardiovascular (CV) outcome (including non-fatal myocardial infarction, non-fatal stroke, de novo HF and CV death). Multivariable proportional hazards regression and sensitivity analyses were used to identify independent correlates of the outcomes.

Results

Among 1330 included patients, the incident rate of de novo HF after transplantation was 58/1000 person-years [95% confidence interval (CI) 50-67] in AVF patients (n = 716) compared with 33/1000 person-years (95% CI 27-41) in non-AVF patients (n = 614). De novo HF was associated with the presence of an AVF [adjusted hazard ratio (aHR) 2.14 (95% CI 1.40-3.26)], duration of dialysis [aHR 1.03/year increase (95% CI 1.01-1.04)], age at transplant [aHR 1.03/year increase (95% CI 1.02-1.05)], female sex [aHR 1.93 (95% CI 1.40-2.65)] and pretransplant diabetes [aHR 2.43 (95% CI 1.48-4.01)]. The presence of an AVF was also associated with the composite CV outcome [aHR 1.91 (95% CI 1.31-2.78)].

Conclusions

The presence of an AVF may be an underrecognized modifiable predictor of de novo HF posttransplantation.

Cost-effectiveness of canagliflozin and dapagliflozin for treatment of patients with chronic kidney disease and type 2 diabetes

AIM

To examine the cost-effectiveness of adding canagliflozin or dapagliflozin to standard of care (SoC) versus SoC alone in patients with chronic kidney disease (CKD) and type 2 diabetes (T2D).

MATERIALS AND METHODS

We used a Markov microsimulation model to assess the cost-effectiveness of canagliflozin plus SoC (canagliflozin + SoC), dapagliflozin plus SoC (dapagliflozin + SoC) and SoC alone. Analyses were conducted from a healthcare system perspective. Costs were measured in 2021 Canadian dollars (C$), and effectiveness was measured in quality-adjusted life-years (QALYs).

RESULTS

Over a patient's lifetime, canagliflozin + SoC and dapagliflozin + SoC yielded cost savings of C$33 460 and C$26 764 and generated 1.38 and 1.44 additional QALYs compared with SoC alone, respectively. While QALY gains with dapagliflozin + SoC were higher than those with canagliflozin + SoC, this strategy was also more costly with the incremental cost-effectiveness ratio exceeding the willingness to pay threshold of C$50 000 per QALY. Dapagliflozin + SoC, however, generated cost savings and QALY gains compared with canagliflozin + SoC over shorter time horizons of 5 or 10 years.

CONCLUSIONS

Dapagliflozin + SoC was not cost-effective versus canagliflozin + SoC in patients with CKD and T2D over the lifetime horizon. However, adding canagliflozin or dapagliflozin to SoC was less costly and more effective relative to SoC alone for treatment of CKD and T2D.

Inequalities and outcomes: end stage kidney disease in ethnic minorities

Background

The international evidence about outcomes of End Stage Kidney Disease (ESKD) for ethnic minorities was reviewed to identify gaps and make recommendations for researchers and policy makers.

Methods

Nine databases were searched systematically with 112 studies from 14 different countries included and analysed to produce a thematic map of the literature.

Results

Reviews (n = 26) highlighted different mortality rates and specific causes between ethnic groups and by stage of kidney disease associated with individual, genetic, social and environmental factors. Primary studies focussing on uptake of treatment modalities (n = 19) found ethnic differences in access. Research evaluating intermediate outcomes and quality of care in different treatment phases (n = 35) e.g. dialysis adequacy, transplant evaluation and immunosuppression showed ethnic minorities were disadvantaged. This is despite a survival paradox for some ethnic minorities on dialysis seen in studies of longer term outcomes (n = 29) e.g. in survival time post-transplant and mortality. There were few studies which focussed on end of life care (n = 3) and ethnicity.

Gaps identified were: limited evidence from all stages of the ESKD pathway, particularly end of life care; a lack of system oriented studies with a reliance on national routine datasets which are limited in scope; a dearth of qualitative studies; and a lack studies from many countries with limited cross country comparison and learning.

Conclusions

Differences between ethnic groups occur at various points and in a variety of outcomes throughout the kidney care system. The combination of individual factors and system related variables affect ethnic groups differently indicating a need for culturally intelligent policy informed by research to prevent disadvantage.

Heart failure in chronic kidney disease: conclusions from a Kidney Disease: Improving Global Outcomes (KDIGO) Controversies Conference

The incidence and prevalence of heart failure (HF) and chronic kidney disease (CKD) are increasing, and as such a better understanding of the interface between both conditions is imperative for developing optimal strategies for their detection, prevention, diagnosis, and management. To this end, Kidney Disease: Improving Global Outcomes (KDIGO) convened an international, multidisciplinary Controversies Conference titled Heart Failure in CKD. Breakout group discussions included (i) HF with preserved ejection fraction (HFpEF) and nondialysis CKD, (ii) HF with reduced ejection fraction (HFrEF) and nondialysis CKD, (iii) HFpEF and dialysis-dependent CKD, (iv) HFrEF and dialysis-dependent CKD, and (v) HF in kidney transplant patients. The questions that formed the basis of discussions are available on the KDIGO website http://kdigo.org/conferences/heart-failure-in-ckd/, and the deliberations from the conference are summarized here.

Impact of Early Hospital Readmissions After Kidney Transplantation on Graft Function

Early hospital readmissions are common after kidney transplantation. This single-center retrospective study investigated the relationship between early hospital readmissions and clinical outcomes. All adult patients receiving a kidney transplant at this center between March 2009 and June 2015 were included. The early hospital readmissions within the first 30 days were numbered, and the diagnosis was ascertained. The patients were divided into None and Readmission groups. Clinical outcomes and patient- and death-censored graft survival were compared. Among the 103 patients included in the study, 32 (31.1%) had 1 or more readmissions within 30 days. Surgical complications, electrolyte imbalance, and acute rejection were common causes of readmission. No differences were observed in baseline characteristics between the two groups. Patients with early readmissions exhibited low renal function at 3, 6, and 12 months postoperatively (P = .002, .020, and .013, respectively). No difference in graft function was found 12 months after transplantation between the None and Readmission groups. Five-year graft and patient survival also showed no difference between the two groups (P = .424 and .442, respectively). In conclusion, early readmission after kidney transplantation affected lower graft function until 1 year after kidney transplantation. However, the long-term effect on graft function is limited in this study.

Predictors and prognostic implications of major adverse cardiovascular events after renal transplant: 10 years outcomes in 321 patients

Renal transplantation is the treatment of choice in patients with end-stage renal disease. Major adverse cardiac events (MACE) are common after renal transplant, especially in the perioperative period, leading to excess morbidity and mortality. The predictors and long-term prognostic implications of MACE are poorly understood. We analyzed predictors and implications of MACE in a cohort of 321 consecutive adult patients, who received renal allograft transplantation between 1995 and 2003 at our institution. The characteristics of 321 patients were: age at transplant 44 ± 13 years, 60% male, 36% diabetes mellitus (DM), left ventricular ejection fraction (LVEF) 60 ± 16%. MACE occurred in 21 patients with cumulative rate of 6.5% over 3 years after renal transplant, 57% occurring within 30 days, 67% within 90 days, and 86% within 180 days. MACE was not predicted by any clinical or pharmacological variables including age, gender, hypertension, DM, prior myocardial infarction, smoking, duration of dialysis, LVEF, or therapy with β-blockers (BB), angiotensin converting enzyme inhibitors, or calcium channel blockers. However, a clinical decision to perform a stress test or a coronary angiogram was predictive of higher MACE rate. MACE, irrespective of type, was independently associated with higher mortality over a period up to 15 years and this seemed to be blunted by BB therapy. MACE rate after renal transplantation decreases over time, most occurring in the first 90 days and is not predicted by any of the traditional risk factors or drug therapies. It is associated with higher long-term mortality.

Long-term outcomes in African American kidney transplant recipients under contemporary immunosuppression: a four-yr analysis of the Mycophenolic acid Observational REnal transplant (MORE) study

Mycophenolic acid Observational REnal transplant (MORE) was a prospective, observational study of de novo kidney transplant patients receiving mycophenolic acid (MPA). Four-yr data on 904 patients receiving tacrolimus and enteric-coated mycophenolate sodium (EC-MPS) or mycophenolate mofetil (MMF) were analyzed to evaluate immunosuppression and graft outcomes in African American (AA, n = 218) vs. non-AA (n = 686) patients. Mean tacrolimus dose was higher in AA vs. non-AA patients but mean tacrolimus trough concentration was similar. Use of the recommended MPA dose in AA patients decreased from 78.9% at baseline to 33.1% at year 3. More AA patients received the recommended MPA dose with EC-MPS than MMF at month 6 (56.2% vs. 35.7%, p = 0.016) and month 36 (46.6% vs. 16.7%, p = 0.029), with no safety penalty. Significantly, more AA patients received corticosteroids than non-AA patients. Biopsy-proven acute rejection was higher in AA vs. non-AA patients (18.9% vs. 10.7%, p = 0.003), as was graft loss (10.9% vs. 4.4%, p = 0.003); differences were confirmed by Cox regression analysis. Patient survival was similar. Estimated GFR was comparable in AA vs. non-AA patients. Kidney allograft survival remains lower for AA vs. non-AA recipients even under the current standard of care.

Cardiovascular complications after transplantation: treatment options in solid organ recipients

Premature cardiovascular disease is the commonest cause of death in solid organ transplant recipients, with coronary artery disease, sudden cardiac death and heart failure being highly prevalent. There are unique factors leading to CV disease in organ transplant recipients that include underlying comorbidities, and metabolic effects of immunosuppression. As a consequence management strategies developed in the general population may have limited benefit. In this review, we will focus on renal transplantation, where most research has been carried out and, despite incomplete understanding of the disease process, the incidence of cardiovascular disease appears to be falling.

Cardiovascular disease in renal transplant recipients

Renal transplant recipients have a markedly increased risk of premature cardiovascular disease (CVD) compared with the general population, although considerably lower than that of patients receiving maintenance haemodialysis. CVD in transplant recipients is poorly characterised and differs from the nonrenal population, with a much higher proportion of fatal to nonfatal cardiac events. In addition to traditional ischaemic heart disease risk factors such as age, gender, diabetes and smoking, there are additional factors to consider in this population such as the importance of hypertension, left ventricular hypertrophy and uraemic cardiomyopathy. There are factors specific to transplantation such immunosuppressive therapies and graft dysfunction which contribute to this altered risk profile. However, understanding and treatment is limited by the absence of large randomised intervention trials addressing risk factor modification, with the exception of the ALERT study. The approach to managing these patients should begin early and be multifactorial in nature.

Primary care of the renal transplant patient

There has been a remarkable rise in the number of kidney transplant recipients (KTR) in the US over the last decade. Increasing use of potent immunosuppressants, which are also potentially diabetogenic and atherogenic, can result in worsening of pre-existing medical conditions as well as development of post-transplant disease. This, coupled with improving long-term survival, is putting tremendous pressure on transplant centers that were not designed to deliver primary care to KTR. Thus, increasing numbers of KTR will present to their primary care physicians (PCP) post-transplant for routine medical care. Similar to native chronic kidney disease patients, KTRs are vulnerable to cardiovascular disease as well as a host of other problems including bone disease, infections and malignancies. Deaths related to complications of cardiovascular disease and malignancies account for 60-65% of long-term mortality among KTRs. Guidelines from the National Kidney Foundation and the European Best Practice Guidelines Expert Group on the management of hypertension, dyslipidemia, smoking, diabetes and bone disease should be incorporated into the long-term care plan of the KTR to improve outcomes. A number of transplant centers do not supply PCPs with protocols and guidelines, making the task of the PCP more difficult. Despite this, PCPs are expected to continue to provide general preventive medicine, vaccinations and management of chronic medical problems. In this narrative review, we examine the common medical problems seen in KTR from the PCP's perspective. Medical management issues related to immunosuppressive medications are also briefly discussed.

The impact of kidney transplantation on heart failure risk varies with candidate body mass index

BACKGROUND

The relationship of body mass index (BMI) with heart failure (HF) risk before and after kidney transplant is not well described.

METHODS

We examined United States Renal Data System records for 67,591 kidney transplant candidates (1995-2004) with Medicare insurance and BMI data at listing. Heart failure diagnoses were ascertained from Medicare billing claims. Body mass index was categorized per World Health Organization criteria. We modeled time-dependent associations (adjusted hazard ratio, aHR) of transplant with HF risk after listing compared with waiting in each BMI group by multivariable, stratified Cox regression. The time-dependent exposure variables partitioned relative risk of HF after transplant versus waiting into early (90 days) posttransplant periods.

RESULTS

The BMI distribution of listed candidates was as follows: 3.7% under, 40.4% normal, 32.0% over, 16.2% obese, and 7.7% morbidly obese weight. The prevalence of HF among patients awaiting transplant reached 57.4% by 3 years. Deceased-donor transplant was associated with increased early HF risk compared with continued waiting-aHRs ranged from 2.23 for normal-BMI to 2.82 for morbidly obese patients. However, transplant reduced the risk of HF in the late posttransplant period from 54% (aHR 0.46) in normal-BMI to 32% (aHR 0.68) for morbidly obese patients. Relative benefits were largest for normal-weight candidates who received live-donor transplants (aHR 0.31).

CONCLUSIONS

Heart failure risk improves in obese patients in the long term after kidney transplant, but not as much as for nonobese patients. There is need for close monitoring and for new strategies to reduce HF risk in obese patients before and after transplant.

Sensitivity of billing claims for cardiovascular disease events among kidney transplant recipients

BACKGROUND AND OBJECTIVES

Billing claims are increasingly examined beyond administrative functions as outcomes measures in observational research. Few studies have described the performance of billing claims as surrogate measures of clinical events among kidney transplant recipients.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

We investigated the sensitivity of Medicare billing claims for clinically verified cardiovascular diagnoses (five categories) and procedures (four categories) in a novel database linking Medicare claims to electronic medical records of one transplant program. Cardiovascular events identified in medical records for 571 Medicare-insured transplant recipients in 1991 through 2002 served as reference measures.

RESULTS

Within a claims-ascertainment period spanning +/-30 d of clinically recorded dates, aggregate sensitivity of single claims was higher for case definitions incorporating Medicare Parts A and B for diagnoses and procedures (90.9%) compared with either Part A (82.3%) or Part B (84.6%) alone. Perfect capture of the four procedures was possible within +/-30 d or with short claims window expansion, but sensitivity for the diagnoses trended lower with all study algorithms (91.2% with window up to +/-90 d). Requirement for additional confirmatory diagnosis claims did not appreciably reduce sensitivity. Sensitivity patterns were similar in the early compared with late periods of the study.

CONCLUSIONS

Combined use of Medicare Parts A and B billing claims composes a sensitive measure of cardiovascular events after kidney transplant. Further research is needed to define algorithms that maximize specificity as well as sensitivity of claims from Medicare and other insurers as research measures in this population.

Obesity and cardiac risk after kidney transplantation: experience at one center and comprehensive literature review

BACKGROUND

The cardiac implications of obesity in kidney transplant recipients are not well-described.

METHODS

We examined associations of body mass index (BMI) at transplant with posttransplant cardiac risk among 1102 renal allograft recipients at a single center in 1991 to 2004. Cumulative posttransplant incidences of congestive heart failure (CHF), atrial fibrillation (AF), myocardial infarction, and a composite of these cardiac diagnoses were estimated by the Kaplan-Meier method. Bivariate (hazards ratio) and covariate (adjusted hazards ratio) relationships of BMI increments with cardiac risk were modeled by Cox's regression. We also systematically reviewed the literature on BMI and cardiac events after transplant.

RESULTS

In the local data, 5-year cumulative incidence of any cardiac diagnosis rose from 8.67% to 29.35% across the lowest to highest BMI quartiles (P=0.02), driven primarily by increases in CHF and AF. In contrast, the rate of myocardial infarction did not differ by BMI quartile (P=0.56). Each 5 U BMI increase predicted 25% higher risk of the cardiac composite (hazards ratio 1.25, 95% CI 1.07-1.47, P=0.005), a relationship that persisted with significance after covariate adjustment (adjusted hazards ratio 1.19, 95% CI 1.00-1.43, P=0.049). BMI independently predicted cardiac risk in subcohorts with pretransplant heart disease and with nondiabetic renal failure. Data from 26 original articles support BMI as a risk factor for posttransplant CHF and AF, whereas findings for coronary/ischemic outcomes are inconsistent and predominantly negative.

CONCLUSIONS

High BMI at transplant predicts increased cardiac risk, especially of CHF and AF. Further research should examine whether obesity treatment modifies cardiac risk after kidney transplantation.

Variations in the risk for cerebrovascular events after kidney transplant compared with experience on the waiting list and after graft failure

BACKGROUND AND OBJECTIVES

This study examined the risks, predictors, and mortality implications of cerebrovascular disease events after kidney transplantation in a national cohort.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

This analysis used United States Renal Data System registry data to study retrospectively Medicare-insured kidney transplant candidates (n = 51,504), recipients (n = 29,614), and recipients with allograft failure (n = 2954) in 1995 through 2002. New-onset cerebrovascular disease events including ischemic stroke, hemorrhagic stroke, and transient ischemic attacks were ascertained from billing records, and participants were followed until Medicare-end or December 31, 2002. Multivariable survival analysis was used to compare cerebrovascular disease event incidence and risk profiles among the study samples.

RESULTS

The cumulative, 3-yr incidence of de novo cerebrovascular disease events after transplantation was 6.8% and was lower than adjusted 3-yr estimates of 11.8% on the waiting list and 11.2% after graft loss. In time-dependent regression, transplantation predicted a 34% reduction in subsequent, overall cerebrovascular disease events risk compared with remaining on the waiting list, whereas risk for cerebrovascular disease events increased >150% after graft failure. Similar relationships with transplantation and graft loss were observed for each type of cerebrovascular disease event. Smoking was a potentially preventable correlate of posttransplantation cerebrovascular disease events. Women were not protected. All forms of cerebrovascular disease event diagnoses after transplantation predicted increased mortality.

CONCLUSIONS

Along with known benefits for cardiac complications, transplantation with sustained graft function seems to reduce risk for vascular disease events involving the cerebral circulation.

Cardiovascular complications after renal transplantation and their prevention

By the time of renal transplantation, end-stage renal disease patients have a huge burden of cardiovascular disease (CVD) and are heavily saturated with atherosclerotic risk factors. Worsening of preexisting risk factors or new CVD risk factors may develop in the posttransplant period consequent in part to the diabetogenic and atherogenic potential of immunosuppressive drugs. The annual risk of a fatal or non-fatal CVD event of 3.5 to 5% in kidney transplant recipients is 50-fold higher than the general population. Renal allograft dysfunction, proteinuria, anemia, moderate hyperhomocysteinemia and elevated serum C-reactive protein concentrations, each dependently confer greater risk of CVD morbidity and mortality in the posttransplant period. Long-term care of renal transplant recipients should programmatically incorporate the recommendations of the National Kidney Foundation Working Groups and European Best Practice Guidelines Expert Group on Renal Transplantations into the management of hypertension, dyslipidemia, smoking, and posttransplant diabetes mellitus. Timely utilization of coronary revascularization procedures should be undertaken as these treatments are equally effective in the kidney transplant population.

De novo congestive heart failure after kidney transplantation: a common condition with poor prognostic implications

BACKGROUND

We aim to describe the risk, predictors, and outcomes associated with de novo congestive heart failure (CHF) after kidney transplantation.

METHODS

We used registry data from the US Renal Data System to retrospectively investigate de novo CHF in adult Medicare-insured transplant recipients and wait-listed candidates in 1995 to 2001. Heart failure was ascertained from inpatient and outpatient billing records, and participants were followed up until loss of Medicare or December 31, 2001. We used extended Cox hazards analysis to identify independent correlates of posttransplantation de novo CHF (adjusted hazard ratio [AHR], 95% confidence interval [CI]) and examine de novo CHF as a predictor of death and graft loss after transplantation.

RESULTS

In 27,011 transplant recipients, cumulative incidences of de novo CHF were 10.2% (95% CI, 9.8 to 10.6) and 18.3% (95% CI, 17.8 to 18.9) at 12 and 36 months and decreased to less than the demographic-adjusted incidence on the waiting list beyond the early posttransplantation period. Risk factors for de novo CHF included older recipient age, female sex, unemployed status at transplantation, pretransplantation comorbidities (anemia, diabetes mellitus, myocardial infarction, angina, cardiac arrhythmia, and peripheral vascular disease), transplant from older donors, donor cardiovascular death, and delayed graft function. We identified pretransplantation obesity, smoking, and posttransplantation complications, including hypertension, anemia, new-onset diabetes, myocardial infarction, and graft failure, as potentially modifiable correlates of de novo CHF. In separate analyses, de novo CHF predicted death (AHR, 2.6; 95% CI, 2.4 to 2.9) and death-censored graft failure (AHR, 2.7; 95% CI, 2.4 to 3.0).

CONCLUSION

Although associations may not reflect causality, identification of potentially mutable de novo CHF risk factors suggests targets for improving outcomes that should be evaluated prospectively.

Incidence and predictors of myocardial infarction after kidney transplantation

The risk and predictors of post-kidney transplantation myocardial infarction (PTMI) are not well described. Registry data collected by the United States Renal Data System were used to investigate retrospectively PTMI among adult first renal allograft recipients who received a transplant in 1995 to 2000 and had Medicare as the primary payer. PTMI events were ascertained from billing and death records, and participants were followed for up to 3 yr after transplant or until the end of observation (December 31, 2000). Extended Cox's hazards analysis was used to identify independent clinical correlates of PTMI (hazard ratio [HR]) and to examine PTMI as an outcomes predictor. Among 35,847 eligible participants, the cumulative incidence of PTMI was 4.3% (95% confidence interval [CI], 4.1 to 4.5%), 5.6% (95% CI, 5.3 to 5.8%), and 11.1% (95% CI, 10.7 to 11.5%) at 6, 12, and 36 mo, respectively. Risk factors for PTMI included older recipient age, pretransplantation comorbidities (diabetes, angina, peripheral vascular disease, and MI), transplantation from older donors and deceased donors, and delayed graft function. Women, blacks, Hispanics, and employed recipients experienced reduced risk. The hazard of PTMI rose after a diagnosis of posttransplantation diabetes (HR, 1.60; 95% CI, 1.35 to 1.88) and markedly increased after graft failure (HR, 2.78; 95% CI, 2.41 to 3.19). In separate analyses, PTMI predicted death-censored graft failure (HR, 1.89; 95% CI, 1.63 to 2.20) and strongly predicted death in a manner that declined with time after PTMI. Risk factors for PTMI include potentially modifiable posttransplantation complications. Because PTMI in turn predicts graft failure and death, reducing the risk for PTMI may improve outcomes after kidney transplantation.

Cardiovascular diseases in kidney transplant recipients: the role of anemia

Cardiovascular diseases are among the leading causes of mortality and death associated graft loss in kidney transplant recipients. Recently, there has been an increased awareness of the potential role of nontraditional risk factors such as anemia in contributing to the increased burden of cardiovascular diseases in kidney transplant recipients. Studies that are primarily based on retrospective data analyses have shown an association between anemia and cardiovascular outcomes. These findings underscore the need for prospective studies to better understand these risks and to implement management strategies that would have a positive impact on patient and graft outcomes. On the basis of the available data, this article reviews the magnitude of cardiovascular diseases and anemia in kidney transplant recipients with a focus on the role of anemia on cardiovascular outcomes in these patients.

Impact of kidney transplantation on the progression of cardiovascular disease

Kidney transplantation, of all the treatment modalities for end-stage renal disease, affords the greatest potential for prolonged survival and improved quality of life. Great strides in immunosuppressant therapy have improved graft survival and forced clinicians to consider other health-care needs of kidney transplant recipients. Chief among these needs is the prevention and treatment of cardiovascular disease. Cardiovascular disease is the most common cause of death among patients with a working renal allograft. Because therapies for primary and secondary prevention are successful in the general population, transplant clinicians are increasingly focused on preventing or limiting the progression of cardiovascular disease. Initiation of aggressive management of conventional atherosclerotic risk factors and uremia-related risk factors, ideally during the early stages of chronic kidney disease (CKD) or after kidney transplantation, and efforts to delay the progression of kidney disease will hopefully reduce the cardiovascular burden in transplant recipients.

Cardiovascular risk in stage 4 and 5 nephropathy

Severity of heart disease of almost all types, as well as mortality risk associated with heart disease, increases in step with severity of kidney disease, although not necessarily in a linear fashion. Heart failure is more common and just as lethal as ischemic heart disease in patients with severe chronic kidney disease (CKD). The incidence of nonfatal heart disease in dialysis and transplant populations has now been described in detail. Although standard risk factors for heart disease that are more common among patients with CKD than in the general population do not adequately explain the greatly increased risk of heart disease in patients with severe CKD, neither do as yet identified "nontraditional" risk factors. However, in addition to the factors not common in the general population, such as anemia, hyperphosphatemia, and markers of systemic inflammation, patients with CKD in the modern era may also exhibit excessive thrombotic tendencies. Screening for heart disease in this population relies mainly on dobutamine stress echocardiography or nuclear scintigraphy. The role of electron beam CT (EBCT) scanning is currently controversial. The indications for coronary angiography are the same for patients with CKD as for the general population, but patients with CKD are at greatly increased risk for contrast-associated nephropathy, the least controversial preventive therapy, which consists of isotonic saline and N-acetylcysteine. Finally, patients with CKD do not currently receive adequate medical therapy for prevention and treatment of heart disease.

Early renal insufficiency and hospitalized heart disease after renal transplantation in the era of modern immunosuppression

Renal insufficiency has been identified as a risk factor for graft loss and death after renal transplantation but has not been consistently linked to early, nonfatal, hospitalized heart disease (HHD). With the United States Renal Data System database, 29,597 patients who received a kidney transplant between January 1, 1996, and July 31, 2000, with Medicare as the primary payer, and were monitored until December 31, 2000, were studied. Cox proportional-hazards regression models were used to calculate the association of recipient estimated GFR (eGFR) at 1 yr after renal transplantation, as determined with the Modification of Diet in Renal Disease formula, with hospitalization for treatment of acute coronary syndromes (ACS) (International Classification of Diseases, version 9, code 410.x or 411.x) or congestive heart failure (CHF) (code 428.x) 1 to 3 yr after renal transplantation. Rates of ACS and CHF were 2.2 and 4.9%, respectively, for patients with eGFR of <44.8 ml/min per 1.73 m(2), compared with 1.2 and 1.4% for patients with eGFR of >69.7 ml/min per 1.73 m(2). Reduced eGFR (<44.8 ml/min per 1.73 m(2), compared with >69.7 ml/min per 1.73 m(2)) at the end of the first 1 yr after transplantation was independently associated with increased risks of both ACS (adjusted hazard ratio, 2.16; 95% confidence interval, 1.39 to 3.35) and CHF (adjusted hazard ratio, 2.95; 95% confidence interval, 2.24 to 3.90). It was concluded that early renal insufficiency (approximately stage 3 chronic kidney disease) was associated with higher rates of HHD 1 to 3 yr after kidney transplantation. Preservation of renal function after renal transplantation may reduce the rates of HHD, and renal transplant recipients with reduced eGFR should be considered at high risk of developing cardiovascular disease.

Heart failure as a cause for hospitalization in chronic dialysis patients

BACKGROUND

Risk factors for heart failure (HF) have not been reported previously in a nationally representative sample of dialysis patients.

METHODS

We conducted a historic cohort study of 1,995 patients enrolled in the US Renal Data System Dialysis Morbidity and Mortality Study Wave 2 who were Medicare eligible at the study start and were followed up until December 31, 1999, or receipt of a renal transplant. Cox regression analysis was used to model associations with time to first hospitalization for both recurrent and de novo HF (International Classification of Diseases, Ninth Revision code 428.x), defined as patients with and without a history of HF, respectively.

RESULTS

The incidence density of HF was 71/1,000 person-years. Angiotensin-converting enzyme inhibitors and beta-blockers were each used in less than 25% of patients with a known history of HF. A history of coronary heart disease was associated with an increased total risk for HF, as were hemodialysis (versus peritoneal dialysis), aspirin use, and a history of diabetes. However, hemodialysis and aspirin use were the only factors associated with both de novo and recurrent HF. Widened pulse pressure was associated with de novo HF. The mortality rate after HF was 83% at 3 years (adjusted hazard ratio for mortality, 2.10; 95% confidence interval, 1.80 to 2.45; P < 0.0001).

CONCLUSION

In chronic dialysis patients, hemodialysis and aspirin use were associated with increased risk for both total and de novo HF. Hospitalized HF was associated with a significantly increased risk for death.

Congestive heart failure in patients with chronic kidney disease and on dialysis

CHF is highly prevalent in ESRD and is a leading cause of death in such patients. Hypertension, renal anemia, and comorbid conditions such as coronary artery disease are particularly important risk factors for CHF in ESRD. Dialysis hypotension may be a marker of poor prognosis in such persons. Recent studies suggest that lipid peroxidation and L-carnitine deficiency may contribute to CHF in some patients with ESRD. All forms of renal replacement therapy are capable of ameliorating symptoms of CHF, but their effect on cardiovascular mortality has not been firmly established. Drug therapy, particularly angiotensin-converting enzyme inhibitors and beta-adrenergic receptor blockers, is under-used in patients with ESRD and CHF. Heart/kidney transplantation may be a viable option for some patients with advanced CHF and ESRD.

Hospitalized atrial fibrillation after renal transplantation in the United States

Renal transplant recipients have a high incidence of hypertension, a known risk factor for atrial fibrillation (AF), as well as factors that could increase their risk of AF. However, the incidence of, risk factors for, and mortality associated with AF after renal transplantation have not been reported. We present a historical cohort study of 39 628 renal transplant recipients in the United States Renal Data System between 1 July 1994 and 30 June 1998.

DATA SOURCE

USRDS files through May 2000. Associations with hospitalizations for a primary diagnosis of AF (ICD-9 codes 427.31) after renal transplant were assessed by Cox Regression analysis. Tacrolimus was not approved for use by the FDA during the time-frame of the study. The incidence of AF after renal transplantation was 5.8 episodes/1000 person-years. In Cox Regression analysis, recipients who were older age, experienced graft loss, rejection, had higher body mass index, renal failure due to hypertension, and cyclosporine use (vs. tacrolimus use) were associated with increased risk of hospitalized AF. Atrial fibrillation was not uncommon after renal transplantation, and was associated with increased risk of mortality, primarily from cardiovascular disease. The strongest risk factors for AF after renal transplantation were older age, allograft rejection, graft loss and obesity.

Hospitalized nephrolithiasis after renal transplantation in the United States

The national incidence of and risk factors for hospitalized nephrolithiasis (NEP) in renal transplant (RT) recipients has not been reported. We conducted a historical cohort study of 42 096 RT recipients in the United States Renal Data System between 1 July 1994 and 30 June 1998. The 1-year incidence of NEP (ICD-9 codes 592.x) after RT in 1997 was compared to the rate of NEP in the general population using the National Hospital Discharge Survey. Associations with time to hospitalizations for a primary diagnosis of nephrolithiasis were assessed by Cox Regression. NEP was uncommon after RT (104 cases per 100 000 person years in 1997). However, females, but not males, had a statistically significant increased risk of NEP compared to the general population (rate ratio for females, 2.84, 95% confidence interval, 2.35-3.58). Kidney stones were more common than ureteral stones, and percutaneous procedures were more common than ureteroscopy or extracorporeal shock wave lithotripsy (ESWL). The only risk factor identified for NEP was renal failure due to stone disease (only one case). NEP was uncommon after RT, but was still more common than in the general population. We identified differences in the presentation and management of NEP after RT in comparison to the general population.

Diabetic ketoacidosis and hyperglycemic hyperosmolar syndrome after renal transplantation in the United States

BACKGROUND: The incidence and risk factors for diabetic ketoacidosis (diabetic ketoacidosis) and hyperglycemic hyperosmolar syndrome (hyperglycemic hyperosmolar syndrome, previously called non-ketotic hyperosmolar coma) have not been reported in a national population of renal transplant (renal transplantation) recipients. METHODS: We performed a historical cohort study of 39,628 renal transplantation recipients in the United States Renal Data System between 1 July 1994 and 30 June 1998, followed until 31 Dec 1999. Outcomes were hospitalizations for a primary diagnosis of diabetic ketoacidosis (ICD-9 code 250.1x) and hyperglycemic hyperosmolar syndrome (code 250.2x). Cox Regression analysis was used to calculate adjusted hazard ratios for time to hospitalization for diabetic ketoacidosis or hyperglycemic hyperosmolar syndrome. RESULTS: The incidence of diabetic ketoacidosis and hyperglycemic hyperosmolar syndrome were 33.2/1000 person years (PY) and 2.7/1000 PY respectively for recipients with a prior diagnosis of diabetes mellitus (DM), and 2.0/1000 PY and 1.1/1000 PY in patients without DM. In Cox Regression analysis, African Americans (AHR, 2.71, 95 %CI, 1.96-3.75), females, recipients of cadaver kidneys, patients age 33-44 (vs. >55), more recent year of transplant, and patients with maintenance TAC (tacrolimus, vs. cyclosporine) had significantly higher risk of diabetic ketoacidosis. However, the rate of diabetic ketoacidosis decreased more over time in TAC users than overall. Risk factors for hyperglycemic hyperosmolar syndrome were similar except for the significance of positive recipient hepatitis C serology and non-significance of female gender. Both diabetic ketoacidosis (AHR, 2.44, 95% CI, 2.10-2.85, p < 0.0001) and hyperglycemic hyperosmolar syndrome (AHR 1.87, 95% CI, 1.22-2.88, p = 0.004) were independently associated with increased mortality. CONCLUSIONS: We conclude that diabetic ketoacidosis and hyperglycemic hyperosmolar syndrome were associated with increased risk of mortality and were not uncommon after renal transplantation. High-risk groups were identified.

Hospitalized avascular necrosis after renal transplantation in the United States

BACKGROUND

The national incidence of and risk factors for hospitalized avascular necrosis (AVN) in renal transplant recipients has not been reported.

METHODS

This historical cohort study consisted of 42,096 renal transplant recipients enrolled in the United States Renal Data System (USRDS) between 1 July 1994 and 30 June 1998. The data source was USRDS files through May 2000. Associations with hospitalizations for a primary diagnosis of AVN (ICD-9 codes 733.4x) within three years after renal transplant were assessed in an intention-to-treat design by Cox regression analysis.

RESULTS

Recipients had a cumulative incidence of 7.1 episodes/1000 person-years from 1994 to 1998. The two-year incidence of AVN did not change significantly over time. Eighty-nine percent of the cases of AVN were due to AVN of the hip (733.42) and 60.2% of patients with AVN underwent total hip arthroplasty (THA); these percentages did not change significantly over time. In the Cox regression analysis, an earlier year of transplant, African American race [adjusted hazard ratio (AHR), 1.65, 95% confidence interval (CI) 1.33 to 2.03], allograft rejection (AHR 1.67, 95% CI 1.35 to 2.07), peritoneal dialysis (vs. hemodialysis; AHR 1.44, 95% CI 1.15 to 1.81), and diabetes (AHR 0.41, 95% CI 0.27 to 0.64) were the only factors independently associated with hospitalizations for AVN.

CONCLUSIONS

The incidence of AVN did not decline significantly over time in the renal transplant population. Patients with allograft rejection, African American race, peritoneal dialysis and earlier date of transplant were at the highest risk of AVN, while diabetic recipients were at a decreased risk.

Hospitalized poisonings after renal transplantation in the United States

BACKGROUND

The national incidence of and risk factors for hospitalized poisonings in renal transplant recipients has not been reported.

METHODS

Historical cohort study of 39,628 renal transplant recipients in the United States Renal Data System between 1 July 1994 and 30 June 1998. Associations with time to hospitalizations for a primary diagnosis of poisonings (ICD-9 codes 960.x-989.x) within three years after renal transplant were assessed by Cox Regression.

RESULTS

The incidence of hospitalized poisonings was 2.3 patients per 1000 person years. The most frequent causes of poisonings were immunosuppressive agents (25.3%), analgesics/antipyretics (14.1%), psychotropic agents (10.0%), and insulin/antidiabetic agents (7.1%). In Cox Regression analysis, low body mass index (BMI, <21.6 vs. >28.3 kg/m2, adjusted hazard ratio (AHR), 3.02, 95% CI, 1.45-6.28, and allograft rejection, AHR 1.83, 95% CI, 1.15-2.89, were the only factors independently associated with hospitalized poisonings. Hospitalized poisonings were independently associated with increased mortality (AHR, 1.54, 95% CI 1.22-1.92, p = 0.002).

CONCLUSIONS

Hospitalized poisonings were associated with increased mortality after renal transplantation. However, almost all reported poisonings in renal transplant recipients were due to the use of prescribed medications. Allograft rejection and low BMI were the only independent risk factors for poisonings identified in this population.

Graft loss and acute coronary syndromes after renal transplantation in the United States

The impact of graft loss on acute coronary syndromes (ACS) after renal transplantation has not been studied in a national population. It was hypothesized that ACS might be more frequent after graft loss, as many of the benefits of a functioning allograft on metabolism and volume regulation would be lost. Data from the 2000 United States Renal Data System (USRDS) was used to conduct an historical cohort study of ACS in 14,237 patients who received renal transplants between April 1, 1995, and June 30, 1998, (followed until April 28, 2000) with valid information from CMS Form 2728, excluding patients with hospitalized ACS before renal transplant. Cox nonproportional regression models were used to calculate the time-dependent adjusted hazard ratio (AHR) of graft loss (censored for death) for time-to-first hospitalization for ACS (International Classification of Diseases 9th Modification Diagnosis Codes [ICD9] code 410.x or 411.x) occurring after transplant. The incidence of ACS was 12.1 per 1000 patient-years (PY) in patients after graft loss versus 6.5 per 1000 PY after transplantation (excluding patients with graft loss). As a time-dependent variable, graft loss had an AHR of 2.54 (95% confidence interval, 1.09 to 5.96; P = 0.031 by Cox regression). Other risk factors associated with ACS included diabetes, older recipient, and male recipient. Allograft rejection was NS. Renal transplant recipients share some of the risk factors for ACS with the general population. In addition, graft loss was identified as a unique risk factor for ACS in this population.