Austin G. Stack

Mortality Differences by Dialysis Modality among Incident ESRD Patients with and without Coronary Artery Disease

It is unclear whether peritoneal dialysis (PD) compared with hemodialysis (HD) confers a survival advantage in end-stage renal disease (ESRD) patients with coronary artery disease (CAD). This hypothesis was tested in a national cohort of 107,922 patients starting dialysis therapy between May 1, 1995, and July 31, 1997. Data on patient characteristics were obtained from the Center for Medicare and Medicaid Services Medical Evidence Form (CMS) and linked to mortality data from the United States Renal Data System (USRDS). Patients were classified on the basis of CAD presence and followed until death or the end of 2 yr. Nonproportional Cox regression models estimated the relative risk (RR) of death for patients with and without CAD by dialysis modality using primarily the intent-to-treat but also the as-treated approach. Diabetic patients (DM) and nondiabetic patients (non-DM) were analyzed separately. Among DM, patients with CAD treated with PD had a 23% higher RR (95% CI, 1.12 to 1.34) compared with similar HD patients, whereas patients without CAD receiving PD had a 17% higher RR (CI, 1.08 to 1.26) compared with HD. Among non-DM, patients with CAD treated with PD had a 20% higher RR (CI. 1.10 to 1.32) compared with HD patients, whereas patients without CAD had similar survival on PD or HD (RR = 0.99; CI, 0.93 to 1.05). The mortality risk for new ESRD patients with CAD differed by treatment modality. In both DM and non-DM, patients with CAD treated with PD had significantly poorer survival compared with HD. Whether differences in solute clearance and/or cardiac risk profiles between PD and HD may explain these findings deserves further investigation.

Independent and conjoint associations of gout and hyperuricaemia with total and cardiovascular mortality

BACKGROUND Gout and serum uric acid are associated with mortality but their simultaneous contributions have not been fully evaluated in the general population. PURPOSE To explore the independent and conjoint relationships of gout and uric acid with mortality in the US population. METHODS Mortality risks of gout and serum uric acid were determined for 15 773 participants, aged 20 years or older, in the Third National Health and Nutrition Examination Survey by linking baseline information collected during 1988-1994 with mortality data up to 2006. Multivariable Cox proportional hazards regression determined adjusted hazard ratios (HRs) and 95% confidence intervals (CIs) for each exposure and all analyses were conducted in 2011 and 2012. RESULTS Compared with subjects without a history of gout, the multivariable HR for subjects with gout were 1.42 (CI 1.12-1.82) for total and 1.58 (CI 1.13-2.19) for cardiovascular mortality. Adjusted HRs per 59.5 µmol/l (1 mg/dl) increase in uric acid were 1.16 (CI 1.10-1.22) for total and cardiovascular mortality and this pattern was consistent across disease categories. In the conjoint analysis, the adjusted HRs for mortality in the highest two uric acid quartiles were 1.64 (CI 1.08-2.51) and 1.77 (CI 1.23-2.55), respectively, for subjects with gout, and were 1.09 (CI 0.87-1.37) and 1.37 (CI (1.11-1.70), respectively, for subjects without gout, compared with those without gout in the lowest quartile. A similar pattern emerged for cardiovascular mortality. CONCLUSION Gout and serum uric acid independently associate with total and cardiovascular mortality. These risks increase with rising uric acid concentrations.

Exercise and limitations in physical activity levels among new dialysis patients in the United States: an epidemiologic study.

PURPOSE Epidemiologic studies of physical activity among patients with end-stage renal disease (ESRD) are lacking. The aim of this study was to describe the patterns of physical activity among new dialysis patients in the United States. METHODS Multivariate logistic regression analyses examined associations of self-reported limitations in physical activity and exercise frequency with sociodemographic and clinical variables in 2,264 patients from Wave 2 of the Dialysis Morbidity and Mortality Study. RESULTS Overall, 56% of patients exercised less than once a week, 75% reported severe limitations in vigorous activities, whereas 42% had severe limitations in moderate physical activities. Fewer limitations in moderate or vigorous activities correlated positively with male gender (odds-ratio [OR] = 1.61), black race OR =1.49), Hispanic ethnicity (OR = 2.39), serum albumin (OR = 1.69 per 1 g/L higher), positive affect (OR = 2.33), peritoneal dialysis (OR = 1.90), and negatively with age (OR = 0.67), heart failure (OR = 0.75), peripheral vascular disease (OR = 0.69), malnutrition (OR = 0.67), and depression (OR = 0.39). Patients reporting fewer limitations in moderate or vigorous activities (OR = 1.35 and 1.28, respectively), or frequent visits with a dietitian (2 to 3 times per week vs. less) (OR = 1.21) in the pre-ESRD period exercised more frequently. CONCLUSIONS Limitations in physical activity are common among new ESRD patients and these, in part, are related to pre-existing cardiovascular disease, malnutrition, and mental health.

Survival Advantage of Hispanic Patients Initiating Dialysis in the United States Is Modified by Race

Differences in survival have been reported among ethnic groups in the general population. Whether these extend to patients with ESRD is unclear. Using national data, mortality risks of ethnic groups who began dialysis treatment in the United States between May 1, 1995, and July 31, 1997, were compared over 2 yr. Patients were classified as Hispanic or non-Hispanic and then subclassified by race forming six race-specific subgroups: Hispanic white, black, and other and non-Hispanic white, black, and other. Mortality rates for Hispanics compared with non-Hispanics were 19.2 versus 26 per 100 patient-years at risk for those with diabetes and were 14.7 versus 22.7 per 100 patient-years at risk for those without diabetes. For those with diabetes, adjusted mortality risks for Hispanics versus non-Hispanics were 30% lower (95% confidence interval [CI], 26 to 34%). In subgroup analysis, mortality risks for Hispanic whites and Hispanic blacks were 35% (95% CI, 31 to 39%) and 33% (95% CI, 12 to 48%) lower than non-Hispanic whites and were similar in magnitude to those of non-Hispanic blacks (32% lower; 95% CI, 29 to 35%) and non-Hispanic other (33% lower; 95% CI, 28 to 39%). Interestingly, mortality risks for Hispanic others were not significantly different from non-Hispanic whites. For those without diabetes, adjusted mortality risks for Hispanics versus non-Hispanics were 17% lower (95% CI, 9 to 23%), and subgroup analysis yielded similar patterns to those of individuals with diabetes. The survival advantage of Hispanic over non-Hispanic patients who receive chronic dialysis treatment in the United States is not consistent across subgroups and is modified by race. Cultural and genetic differences as well as variation in the access and delivery of care before and while on dialysis may account for these differences.

Surveillance of chronic kidney disease around the world: tracking and reining in a global problem.

In recent years, there has been a general recognition of the importance of tackling noncommunicable chronic diseases throughout the world and not just in developed nations. Chronic kidney disease (CKD) is increasingly recognized as a public health threat, based on its high prevalence, rising incidence, associated complications, and cost. It is imperative that nations develop screening and surveillance programs related to CKD. This article provides a global perspective on existing and emerging CKD surveillance efforts. A variety of programs are described, ranging from cross-sectional screening studies to determine CKD prevalence; targeted screening of high-risk populations presenting for voluntary testing; to more systematic surveillance within the scope of integrated health care systems in many developed nations. The choice of surveillance programs for many countries will depend on available resources and competing health care priorities. Integration with surveillance programs for other major chronic diseases such as diabetes, hypertension, and obesity is highly desirable and could be a key to the prevention of CKD. Finally, we propose the model of integrated health systems as one that is perhaps best suited to systematic, longitudinal surveillance of many chronic diseases, a model based on a national electronic health care record with linkage across primary care and hospital-based programs. Robust health education efforts and timely dissemination strategies will remain the key to the success of disease surveillance. It is gratifying to note that more and more countries are developing and adopting CKD surveillance programs as part of national disease prevention strategies.

The global nephrology workforce: emerging threats and potential solutions!

Amidst the rising tide of chronic kidney disease (CKD) burden, the global nephrology workforce has failed to expand in order to meet the growing healthcare needs of this vulnerable patient population. In truth, this shortage of nephrologists is seen in many parts of the world, including North America, Europe, Australia, New Zealand, Asia and the African continent. Moreover, expert groups on workforce planning as well as national and international professional organizations predict further reductions in the nephrology workforce over the next decade, with potentially serious implications. Although the full impact of this has not been clearly articulated, what is clear is that the delivery of care to patients with CKD may be threatened in many parts of the world unless effective country-specific workforce strategies are put in place and implemented. Multiple factors are responsible for this apparent shortage in the nephrology workforce and the underpinning reasons may vary across health systems and countries. Potential contributors include the increasing burden of CKD, aging workforce, declining interest in nephrology among trainees, lack of exposure to nephrology among students and residents, rising cost of medical education and specialist training, increasing cultural and ethnic disparities between patients and care providers, increasing reliance on foreign medical graduates, inflexible work schedules, erosion of nephrology practice scope by other specialists, inadequate training, reduced focus on scholarship and research funds, increased demand to meet quality of care standards and the development of new care delivery models. It is apparent from this list that the solution is not simple and that a comprehensive evaluation is required. Consequently, there is an urgent need for all countries to develop a policy framework for the provision of kidney disease services within their health systems, a framework that is based on accurate projections of disease burden, a full understanding of the internal care delivery systems and a framework that is underpinned by robust health intelligence on current and expected workforce numbers required to support the delivery of kidney disease care. Given the expected increases in global disease burden and the equally important increase in many established kidney disease risk factors such as diabetes and hypertension, the organization of delivery and sustainability of kidney disease care should be enshrined in governmental policy and legislation. Effective nephrology workforce planning should be comprehensive and detailed, taking into consideration the structure and organization of the health system, existing care delivery models, nephrology workforce practices and the size, quality and success of internal nephrology training programmes. Effective training programmes at the undergraduate and postgraduate levels, adoption of novel recruitment strategies, flexible workforce practices, greater ownership of the traditional nephrology landscape and enhanced opportunities for research should be part of the implementation process. Given that many of the factors that impact on workforce capacity are generic across countries, cooperation at an international level would be desirable to strengthen efforts in workforce planning and ensure sustainable models of healthcare delivery.

Cigarette use and cardiovascular risk in chronic kidney disease: an unappreciated modifiable lifestyle risk factor.

Tobacco use is a major modifiable cardiovascular risk factor in the general population and contributes to excess cardiovascular risk. Emerging evidence from large‐scale observational studies suggests that continued tobacco use is also an independent cardiovascular risk factor among patients with chronic kidney disease (CKD). The benefits of smoking cessation programs on improving the heath status of patients and reducing mortality are unequivocal in the general population. Despite this, there has been little effort in pursuing tobacco cessation programs in dialysis cohorts or those with lesser degrees of kidney impairment. Most of our attention to date has focused on the development of “kidney‐specific” interventions that reduce rates of renal disease progression and improve dialysis outcomes. The purpose of this current review is to describe the epidemiology of tobacco use among patients with CKD, draw attention to its negative impact on cardiovascular morbidity and mortality, and finally highlight potential strategies for successful intervention. We hope that this study heightens the importance of tobacco use in CKD, stimulates renewed interest in the barriers and challenges that exist in achieving smoking cessation, and endorses the efficacy of intervention strategies and the immeasurable benefits of quitting on cardiovascular and noncardiovascular outcomes.

Renal Replacement Therapy in the Elderly: Medical, Ethical, and Psychosocial Considerations

As patients over the age of 65 become the fastest growing segment of our treated end-stage renal disease (ESRD) population, nephrologists and allied healthcare workers who care for these patients must become well versed in the many issues specific to this group. Elderly patients contribute the greatest fraction to the incidence and prevalence of the United States ESRD population. Their life expectancy is greatly reduced compared with age-matched counterparts from the general population. Cardiac disease is the leading cause of death. Although renal transplantation remains the most successful form of renal replacement therapy, only a small fraction of elderly ESRD patients are transplanted. The renal research community has made great strides in improving patient outcomes on dialysis over the last decade in many areas; however, little attention has been focused on the elderly ESRD patient. The substantial mortality and comorbidity experienced by this population makes their management an ongoing challenge. Many unresolved issues remain for elderly ESRD patients in the timing of dialysis initiation, choice of dialytic therapy, use of renal transplantation, and management of cardiovascular disease. It is anticipated that future research in these areas will identify optimal treatment strategies for elderly ESRD patients starting on dialysis and improve patient outcomes.

The Impact of Chronic Obstructive Pulmonary Disease and Smoking on Mortality and Kidney Transplantation in End-Stage Kidney Disease

Background: Chronic obstructive pulmonary disease (COPD) and tobacco use are leading causes of morbidity and mortality. The prevalence and clinical impact of COPD on mortality and kidney transplantation among patients who begin dialysis therapy is unclear. Methods: We explored the clinical impact of COPD and continued tobacco use on overall mortality and kidney transplantation in a national cohort study of US dialysis patients. National data on all dialysis patients (n = 769,984), incident between May 1995 and December 2004 and followed until October 31, 2006, were analyzed from the United States Renal Data System. Prevalence and period trends were determined while multivariable Cox regression evaluated relative hazard ratios (RR) for death and kidney transplantation. Results: The prevalence of COPD was 7.5% overall and increased from 6.7 to 8.1% from 1995–2004. COPD correlated significantly with older age, cardiovascular conditions, cancer, malnutrition, poor functional status, and tobacco use. Adjusted mortality risks were significantly higher for patients with COPD (RR = 1.20, 95% CI 1.18–1.21), especially among current smokers (RR = 1.28, 95% CI 1.25–1.32), and varied inversely with advancing age. In contrast, the adjusted risks of kidney transplantation were significantly lower for patients with COPD (RR = 0.47, 95% CI 0.41–0.54, for smokers and RR = 0.54, 95% CI 0.50–0.58, for non-smokers) than without COPD [RR = 0.72, 95% CI 0.70–0.75, for smokers and RR = 1.00 for non-smokers (referent category)]. Conclusions: Patients with COPD who begin dialysis therapy in the US experience higher mortality and lower rates of kidney transplantation, outcomes that are far worse among current smokers.

Survival Trends of US Dialysis Patients with Heart Failure: 1995 to 2005

BACKGROUND AND OBJECTIVES Congestive heart failure (CHF) is a major risk factor for death in end-stage kidney disease; however, data on prevalence and survival trends are limited. The objective of this study was to determine the prevalence and mortality effect of CHF in successive incident dialysis cohorts. DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS This was a population-based cohort of incident US dialysis patients (n = 926,298) from 1995 to 2005. Age- and gender-specific prevalence of CHF was determined by incident year, whereas temporal trends in mortality were compared using multivariable Cox regression. RESULTS The prevalence of CHF was significantly higher in women than men and in older than younger patients, but it did not change over time in men (range 28% to 33%) or women (range 33% to 36%). From 1995 to 2005, incident death rates decreased for younger men (≤70 years) and increased for older men (>70 years). For women, the pattern was similar but less impressive. During this period, the adjusted mortality risks (relative risk [RR]) from CHF decreased in men (from RR = 1.06 95% Confidence intervals (CI) 1.02-1.11 in 1995 to 0.91 95% CI 0.87-0.96 in 2005) and women (from RR = 1.06 95% CI 1.01-1.10 in 1995 to 0.90 95% CI 0.85-0.95 in 2005 compared with referent year 2000; RR = 1.00). The reduction in mortality over time was greater for younger than older patients (20% to 30% versus 5% to 10% decrease per decade). CONCLUSIONS Although CHF remains a common condition at dialysis initiation, mortality risks in US patients have declined from 1995 to 2005.