Differences in Use of Peritoneal Dialysis and Survival Among East Asian, Indo Asian, and White ESRD Patients in Canada

BACKGROUND

Racial differences in health outcomes in general are well documented; however, few studies examined the impact of East Asian and Indo Asian race on choice of dialytic modality and survival among patients with end-stage renal disease (ESRD).

METHODS

We compared the use of peritoneal dialysis (PD) and survival among East Asian, Indo Asian, and white patients with ESRD initiating dialysis therapy in Canada between January 1, 1990, and December 31, 2000.

RESULTS

Of 10,338 patients, 5.7% were East Asian, 3.2% were Indo Asian, and 91% were white. After controlling for sociodemographics and comorbidities, East Asian and Indo Asian patients were significantly more likely to initiate dialysis therapy on PD compared with white patients (odds ratio, 1.63; 95% confidence interval [CI], 1.36 to 1.96; odds ratio, 1.52; 95% CI, 1.21 to 1.93, respectively), with no difference in likelihood of technique failure. East Asian and Indo Asian patients had a lower risk for death after the initiation of dialysis therapy (irrespective of modality) compared with white patients, with adjusted hazard ratios of 0.66 (95% CI, 0.58 to 0.76) for East Asian patients and 0.63 (95% CI, 0.53 to 0.75) for Indo Asian patients. The survival benefit for East Asian and Indo Asian patients was similar in the subgroup that initiated dialysis therapy with PD.

CONCLUSION

We found that Asian patients with ESRD were more likely to initiate dialysis therapy using PD, with improved survival after the initiation of dialysis therapy, compared with white patients. Elucidation of factors in East Asian and Indo Asian ESRD populations that result in improved outcomes may have implications for ESRD treatment for other racial groups.

Performance of the automated BpTRU measurement device in the assessment of white-coat hypertension and white-coat effect

OBJECTIVES

BpTRU (VSM MedTech Ltd, Vancouver, Canada) is an automated oscillometric device that provides serial blood pressure measurements in an office setting in the absence of a healthcare professional. We sought to determine whether the white-coat effect is reduced by a blood pressure measurement protocol using BpTRU compared with casual office measurements. Secondarily, we also sought to determine whether a blood pressure measurement protocol using BpTRU reduced white-coat hypertension compared with the casual office measurements, and reduced white-coat effect and white-coat hypertension compared with blood pressure obtained by a research nurse.

METHODS

Blood pressure was measured in 107 adult hypertensive patients referred for ambulatory blood pressure monitoring using an ambulatory blood pressure monitor, a standardized protocol by a trained research nurse, and a protocol using BpTRU (five readings over 25 min, using the 5-min blood pressure measurement interval setting). Casual office blood pressure was also recorded in the family physicians' offices. Using the mean daytime ambulatory blood pressure as the reference standard, the proportion of patients with white-coat effect and white-coat hypertension were determined for measurements obtained by BpTRU, the research nurse, and the family physicians' offices.

RESULTS

Casual office blood pressure measurements demonstrated a white-coat effect in 39 (36.4%) patients; seven (6.5%) patients demonstrated a white-coat effect using BpTRU (P<0.0001). White-coat hypertension was also less common using BpTRU than with the casual office readings (13 vs. 1 patient, P<0.0001). White-coat effect was also reduced with BpTRU compared with the research nurse measurements. Unfortunately, percentage agreement for the diagnosis of hypertension between the protocol using BpTRU and the reference standard was only 48%. This resulted in substantial misclassification of hypertension by the BpTRU measurement protocol.

CONCLUSIONS

Although BpTRU reduces white-coat effect and white-coat hypertension, blood pressure is underestimated by the device, leading to misclassification of hypertension. BpTRU, when set at 5-min blood pressure measurement intervals, should not be used in clinical practice.

Refined characterization of the association between kidney function and mortality in patients undergoing cardiac catheterization

AIMS

Chronic kidney disease is associated with an increased risk of cardiovascular morbidity and mortality. The level of kidney function at which this risk increases remains to be determined. We sought to characterize the relationship between kidney function and survival among patients with cardiovascular disease (CVD) undergoing cardiac catheterization using estimated glomerular filtration rate (eGFR) and graded refinements in the classification of kidney function.

METHODS AND RESULTS

We included 8521 of 11 778 (72.3%) consecutive patients undergoing cardiac catheterization between 1 January 1999 and 31 December 2001 from the Alberta Provincial Project for Outcome Assessment in Coronary Heart Disease database. eGFR as a categorical and continuous variable was used to define kidney function. The outcome was all-cause mortality. During a median (interquartile range) follow-up of 2.2 (1.5-3.1) years, and after adjustment for clinical risk factors and severity of coronary disease, there was a steady incremental decrease in survival post-catheterization corresponding to a decline in eGFR categories of 10 mL/min/1.73 m(2). When eGFR was modelled as a continuous variable, there was an increased risk of death noted at an eGFR below 79 mL/min/1.73 m(2). Below an eGFR of 70 mL/min/1.73 m,(2), there was an approximate 17.2% relative increase in risk for every 10 unit decrease in eGFR (95% CI 8.4-26.6%).

CONCLUSION

The risk of death post-cardiac catheterization is elevated when eGFR is < or =79 mL/min/1.73 m(2). These findings provide considerable refinement in our understanding of eGFR as a powerful prognostic marker in patients with CVD undergoing cardiac catheterization.

Progression of kidney dysfunction in the community-dwelling elderly

Despite the high prevalence of chronic kidney disease among the elderly, few studies have described their loss of kidney function. We sought to determine the progression of kidney dysfunction among a community-based cohort of elderly subjects. The cohort included 10 184 subjects 66 years of age or older, who had one or more outpatient serum creatinine measurements during each of two time periods: 1 July to 31 December 2001 and 1 July to 31 December 2003. A mixed effects model, including covariates for age, gender, diabetes mellitus, and comorbidity, was used to determine the rate of decline in estimated glomerular filtration rate (eGFR, in ml/min/1.73 m2) per year over a median follow-up of 2.0 years. Subjects with diabetes mellitus had the greatest decline in eGFR of 2.1 (95% CI 1.8-2.5) and 2.7 (95% CI 2.3-3.1) ml/min/1.73 m2 per year in women and men, respectively. The rate of decline for women and men without diabetes mellitus was 0.8 (95% CI 0.6-1.0) and 1.4 (95% CI 1.2-1.6) ml/min/1.73 m2 per year. Subjects with a study mean eGFR<30 ml/min/1.73 m2, both those with and without diabetes mellitus, experienced the greatest decline in eGFR. In conclusion, we found that the majority of elderly subjects have no or minimal progression of kidney disease over 2 years. Strategies aimed at slowing progression of kidney disease should consider underlying risk factors for progression and the negligible loss of kidney function that occurs in the majority of older adults.

The effects of nocturnal hemodialysis compared to conventional hemodialysis on change in left ventricular mass: rationale and study design of a randomized controlled pilot study

Background

Nocturnal hemodialysis (NHD) is an alternative to conventional three times per week hemodialysis (CvHD) and has been reported to improve several health outcomes. To date, no randomized controlled trial (RCT) has compared NHD and CvHD. We have undertaken a multi-center RCT in hemodialysis patients comparing the effect of NHD to CvHD on left ventricular (LV) mass, as measured by cardiac magnetic resonance imaging (cMR).

Methodology/design

All patients in Alberta, Canada, expressing an interest in performing NHD are eligible for the study. Patients enrolled in the study will be randomized to either NHD or CvHD for a six month period. All patients will have a full clinical assessment, including collection of biochemical and cMR data at baseline and at 6 months. Both groups of patients will be monitored biweekly to optimize blood pressure (BP) to a goal of <130/80 mmHg post-dialysis using a predefined BP management protocol. The primary outcome is change in LV mass, a surrogate marker for cardiac mortality, measured at baseline and 6 months. The high sensitivity and reproducibility of cMR facilitates reduction of the required sample size and the time needed between measures compared with echocardiography. Secondary outcomes include BP control, anemia, mineral metabolism, health-related quality of life, and costs.

Discussion

To our knowledge, this study will be the first RCT evaluating health outcomes in NHD. The impact of NHD on LV mass represents a clinically important outcome which will further elucidate the potential benefits of NHD and guide future clinical endpoint studies.

Contrast-induced nephropathy: epidemiology and prevention

Contrast-induced nephropathy (CIN) is a leading cause of iatrogenic acute kidney failure. Periprocedural CIN results in a greater risk of requiring renal replacement therapy, prolonged hospitalization, excessive health care costs, potential long term kidney impairment and mortality. Identified risk factors for CIN include premorbid chronic kidney disease, diabetes mellitus, congestive heart failure, critical illness and volume of administered contrast media. Prophylactic interventions for the prevention of CIN remain controversial and uncertain. In this review we critically appraise the evidence for prevention of CIN. In general, every attempt should be made to correct underlying volume depletion, discontinue potential nephrotoxins, reverse any acute kidney dysfunction or when not possible, consider delay of procedure or an alternative modality for imaging. A minimum volume of contrast media should be employed, including going left ventriculogram and performing staged procedures if applicable. There are few interventions with quality evidence for reducing the incidence of CIN. procedure hydration and the use of nonionic iso-osmolar contrast media have consistently demonstrated efficacy. For patients at high risk, there is evidence to suggest benefit with N-acetylcysteine. Clinical studies with adenosine antagonists are encouraging; however, further confirmatory trials are required. Based on the available studies, there is inadequate evidence for the routine use of hemofiltration, atrial natriuretic peptides, calcium channel blockers, or prostaglandins. There is no evidence to support prophylaxis with diuretic therapy, forced diuresis, low dose dopamine, fenoldopam, captopril, or endothelin receptor antagonists. Despite recent advances in the epidemiology, pathophysiology and natural history of CIN, few effective prophylactic or therapeutic interventions have conclusively demonstrated evidence for a reduction in CIN incidence and no therapy has proven efficacious once CIN is established.

Impact of anemia on hospitalization and mortality in older adults

Although anemia is common in older adults, its prognostic significance is uncertain. A total of 17 030 community-dwelling subjects 66 years and older were identified between July 1 and December 31, 2001, and followed until December 31, 2004. Cox proportional hazards analyses were performed to determine the associations between anemia (defined as hemoglobin < 110 g/L) and hemoglobin and all-cause mortality, all-cause hospitalization, and cardiovascular-specific hospitalization. Overall, there were 1983 deaths and 7278 first hospitalizations. In patients with normal kidney function, adjusting for age, sex, diabetes mellitus, and comorbidity, anemia was associated with an increased risk for death (hazard ratio [HR], 4.29; 95% confidence interval [CI], 3.55-5.12), first all-cause hospitalization (HR, 2.16; 95% CI, 1.88-2.48), and first cardiovascular-specific hospitalization (HR, 2.49; 95% CI, 1.99-3.12). An inverse J-shaped relationship between hemoglobin and all-cause mortality was observed; the lowest risk for mortality occurred at hemoglobin values between 130 to 150 g/L for women and 140 to 170 g/L for men. Anemia is associated with an increased risk for hospitalization and death in community-dwelling older adults. Consideration should be given to redefine "normal" hemoglobin values in the elderly. Clinical trials are also necessary to determine whether anemia correction improves quality or quantity of life in this population.

Survival After Coronary Revascularization Among Patients With Kidney Disease

BACKGROUND

The optimal approach to revascularization in patients with kidney disease has not been determined. We studied survival by treatment group (CABG, percutaneous coronary intervention [PCI], or no revascularization) for patients with 3 categories of kidney function: dialysis-dependent kidney disease, non-dialysis-dependent kidney disease, and a reference group (serum creatinine <2.3 mg/dL).

METHODS AND RESULTS

Data were derived from the Alberta Provincial Project for Outcomes Assessment in Coronary Heart Disease (APPROACH), which captures information on all patients undergoing cardiac catheterization in Alberta, Canada. Characteristics and patient survival in 662 dialysis patients (1.6%) and 750 non-dialysis-dependent kidney disease patients (1.8%) were compared with the remainder of the 40,374 patients (96.6%). For the reference group, the adjusted 8-year survival rates for CABG, PCI, and no revascularization (NR) were 85.5%, 80.4%, and 72.3%, respectively (P<0.001 for CABG versus NR; P<0.001 for PCI versus NR). Adjusted survival rates were 45.9% for CABG, 32.7% for PCI, and 29.7% for NR in the nondialysis kidney disease group (P<0.001 for CABG versus NR; P=0.48 for PCI versus NR) and 44.8% for CABG, 41.2% for PCI, and 30.4% for NR in the dialysis group (P=0.003 for CABG versus NR; P=0.03 for PCI versus NR).

CONCLUSIONS

Compared with no revascularization, CABG was associated with better survival in all categories of kidney function. PCI was also associated with a lower risk of death than no revascularization in reference patients and dialysis-dependent kidney disease patients but not in patients with non-dialysis-dependent kidney disease. The presence of kidney disease or dependence on dialysis should not be a deterrent to revascularization, particularly with CABG.

Inadequate Treatment of Cardiovascular Disease and Cardiovascular Disease Risk Factors in Dialysis Patients: A Commentary

Cardiovascular disease (CVD) is the leading cause of morbidity and mortality in patients with end-stage renal disease (ESRD). Despite its significant impact on health outcomes, which would imply a need for aggressive intervention, both CVD and CVD risk factors are inadequately treated in this patient population. The reasons for this inadequate treatment are unclear. This article reviews the contribution of traditional risk factors to the burden of CVD in ESRD patients, outlines the evidence regarding undertreatment of CVD and traditional CVD risk factors, and identifies potential factors that may be responsible for inadequate cardiovascular care in ESRD patients.

Is chronic kidney disease a cardiovascular disease risk factor?

Cardiovascular disease (CVD) is prevalent in patients with chronic kidney disease (CKD) and may account for 50% of all deaths. The recent Dialysis Outcomes Quality Initiative (DOQI) publication on the evaluation, classification, and stratification of CKD states that a reduced glomerular filtration rate (GFR) identifies individuals at greater risk for CVD and death. This risk is the result of traditional and nontraditional CVD risk factors. However, the relative contribution of these risk factors in the CKD population remains uncertain. Recently interest in kidney disease (reduced GFR) as an independent nontraditional risk factor for CVD has come to the forefront. Studies examining this potential link have included community-based cohort studies, studies in patients with extensive comorbidity, and reports in kidney transplant recipients. Herein, results from these studies are reviewed. The difference between an independent CVD risk factor and a causal CVD risk factor is discussed, with particular emphasis on the temporal association between exposure (GFR) and outcome (CVD and CVD death).

Uric acid and cardiovascular disease: a renal-cardiac relationship?

Elevated serum uric acid is a frequent finding in patients with kidney disease and cardiovascular disease. Intrarenal ischaemia, induced by hypertension, increased sympathetic nervous system activity, and hyperinsulinaemia have all been implicated in reduced renal clearance of urate. This frequently results in elevated serum uric acid levels. The association of hyperuricaemia with cardiovascular disease remains controversial. Current evidence suggests that serum uric acid may provide additional prognostic information in patients with essential hypertension. However, there has been no test of the hypothesis that a reduction in serum uric acid would prevent cardiovascular disease. Furthermore, a critical review of the current literature does not support a causal role of serum uric acid in the development of cardiovascular disease. Serum uric acid probably reflects and integrates different risk factors and their possible interactions.

Proteinuria as a risk factor for cardiovascular disease and mortality in older people: a prospective study

BACKGROUND

The prognostic significance of proteinuria in older people is not well defined. We examined the associations between proteinuria and incident coronary heart disease, cardiovascular mortality, and all-cause mortality in older people.

SUBJECTS AND METHODS

Casual dipstick proteinuria was determined in 1,045 men (mean [+/- SD] age 68 +/- 7 years) and 1,541 women (mean age 69 +/- 7 years) attending the 15th biennial examination of the Framingham Heart Study. Participants were divided by grade of proteinuria: none (85.3%), trace (10.2%), and greater-than-trace (4.5%). Cox proportional hazards analyses were used to determine the relations of baseline proteinuria to the specified outcomes, adjusting for other risk factors, including serum creatinine level.

RESULTS

During 17 years of follow-up, there were 455 coronary heart disease events, 412 cardiovascular disease deaths, and 1,214 deaths. In men, baseline proteinuria was associated with all-cause mortality (hazards ratio [HR] = 1.3, 95% confidence interval [CI] 1.0 to 1.7 for trace proteinuria; HR = 1.3, 95% CI 1.0 to 1.8 for greater-than-trace proteinuria; P for trend = 0.02). In women, trace proteinuria was associated with cardiovascular disease death (HR = 1. 6, 95% CI 1.1 to 2.4), and all-cause mortality (HR = 1.4, 95% CI 1.1 to 1.7).

CONCLUSION

Proteinuria is a significant, although relatively weak, risk factor for all-cause mortality in men and women, and for cardiovascular disease mortality in women.

Cardiovascular disease and mortality in a community-based cohort with mild renal insufficiency

Cardiovascular disease and mortality in a community-based cohort with mild renal insufficiency.

BACKGROUND

Little is known about the prevalence of cardiovascular disease (CVD) and associated risk factors in individuals with mild renal insufficiency (RI). Furthermore, the long-term outcomes associated with mild RI in the community have not been described.

METHODS

Serum creatinine (SCr) was measured in 6233 adult participants of the Framingham Heart Study (mean age 54 years, 54% women). Mild RI was defined as SCr 136 to 265 micromol/liter (1.5 to 3.0 mg/dl) in men and 120 to 265 micromol/liter (1.4 to 3.0 mg/dl) in women. The lower limits for mild RI were defined by the sex-specific 95th percentile SCr values in a healthy subgroup of our sample. The upper limit for mild RI was chosen to exclude those subjects with more advanced renal failure. Cox proportional hazards analyses were used to determine the relationship of baseline RI to CVD and all-cause mortality.

RESULTS

At baseline, 8.7% of men (N = 246) and 8.0% of women (N = 270) had mild RI. Nineteen percent of the subjects with mild RI had prevalent CVD. During 15 years of follow-up, there were 1000 CVD events and 1406 deaths. In women, mild RI was not associated with increased risk for CVD events [hazards ratio (HR) 1.04, 95% CI, 0.79 to 1.37] or all-cause mortality (HR 1.08, 95% CI, 0.87 to 1.34). In men, mild RI showed no significant associations with CVD events (HR 1.17, 95% CI, 0.88 to 1.57), but it was associated with all-cause mortality in age-adjusted (HR 1.42, 95% CI, 1.12 to 1.79) and multivariable adjusted (HR 1.31, 95% CI, 1.02 to 1.67) analyses.

CONCLUSION

Mild RI in the community is common and is associated with a high prevalence of CVD. The association of RI with risk for adverse outcomes is strongly related to coexisting CVD and CVD risk factors.

Prevalence and correlates of elevated serum creatinine levels: the Framingham Heart Study

BACKGROUND

Elevated serum creatinine (SCr) levels are a predictor of end-stage renal disease, but little is known about the prevalence of elevated SCr levels and their correlates in the community.

METHODS

In this cross-sectional, community-based sample, SCr levels were measured in 6233 adults (mean age, 54 years; 54% women) who composed the "broad sample" of this investigation. A subset, consisting of 3241 individuals who were free of known renal disease, cardiovascular disease, hypertension, and diabetes, constituted the healthy reference sample. In this latter sample, sex-specific 95th percentiles for SCr levels (men, 136 micromol/L [1.5 mg/dL]; women, 120 micromol/L [1.4 mg/dL]) were labeled cutpoints. These cutpoints were applied to the broad sample in a logistic regression model to identify prevalence and correlates of elevated SCr levels.

RESULTS

The prevalence of elevated SCr levels was 8.9% in men and 8.0% in women. Logistic regression in men identified age, treatment for hypertension (odds ratio [OR], 1.75; 95% confidence interval [CI], 1.27-2.42), and body mass index (OR, 1.08; 95% CI, 1.01-1.15) as correlates of elevated SCr levels. Additionally, men with diabetes who were receiving antihypertensive medication were more likely to have raised SCr values (OR, 2.94; 95% CI, 1.60-5.39). In women, age, use of cardiac medications (OR, 1.58; 95% CI, 1.10-2.96), and treatment for hypertension (OR, 1.42; 95% CI, 1.07-1.87) were associated with elevated SCr levels.

CONCLUSIONS

Elevated SCr levels are common in the community and are strongly associated with older age, treatment for hypertension, and diabetes. Longitudinal studies are warranted to determine the clinical outcomes of individuals with elevated levels of SCr and to examine factors related to the progression of renal disease in the community.

Serum uric acid and risk for cardiovascular disease and death: the Framingham Heart Study

BACKGROUND

Hyperuricemia is associated with risk for cardiovascular disease and death. However, the role of uric acid independent of established risk factors is uncertain.

OBJECTIVE

To examine the relation of serum uric acid level to incident coronary heart disease, death from cardiovascular disease, and death from all causes.

DESIGN

Community-based, prospective observational study.

SETTING

Framingham, Massachusetts.

PATIENTS

6763 Framingham Heart Study participants (mean age, 47 years).

MEASUREMENTS

Serum uricacid level at baseline (1971 to 1976); event rates per 1000 person-years by sex-specific uric acid quintile.

RESULTS

During 117,376 person-years of follow-up, 617 coronary heart disease events, 429 cardiovascular disease deaths, and 1460 deaths from all causes occurred. In men, after adjustment for age, elevated serum uric acid level was not associated with increased risk for an adverse outcome. In women, after adjustment for age, uric acid level was predictive of coronary heart disease (P = 0.002), death from cardiovascular disease (P = 0.009), and death from all causes (P = 0.03). After additional adjustment for cardiovascular disease risk factors, uric acid level was no longer associated with coronary heart disease, death from cardiovascular disease, or death from all causes. In a stepwise Cox model, diuretic use was identified as the covariate responsible for rendering serum uric acid a statistically nonsignificant predictor of outcomes.

CONCLUSIONS

These findings indicate that uric acid does not have a causal role in the development of coronary heart disease, death from cardiovascular disease, or death from all causes. Any apparent association with these outcomes is probably due to the association of uric acid level with other risk factors.

Cardiovascular disease: risk factors, secular trends, and therapeutic guidelines

A brief review of cardiovascular disease incidence and risk factors for coronary heart disease and cardiac failure is presented. Secular trends in cardiovascular disease risk factors, morbidity, and mortality are a major focus. Declines in cardiovascular disease mortality over the past 30 yr, a more modest decline in coronary heart disease, and an increase in cardiac failure are demonstrated. Emphasis is placed on evidence from large-scale, prospective, observational and interventional studies, and the pertinent U.S. guidelines and recommendations for care are provided. Consideration is given to the major risk factors, including lipids, blood pressure, smoking, and diabetes mellitus. Additional information is also given concerning the role of vitamins, homocysteine metabolism, and left ventricular hypertrophy. Although this review focuses on commonly accepted risk factors in the general population, where appropriate, specific information that is relevant to patients with chronic renal disease is provided.