Acute kidney injury increases risk of ESRD among elderly.

Risk for ESRD among elderly patients with acute kidney injury (AKI) has not been studied in a large, representative sample. This study aimed to determine incidence rates and hazard ratios for developing ESRD in elderly individuals, with and without chronic kidney disease (CKD), who had AKI. In the 2000 5% random sample of Medicare beneficiaries, clinical conditions were identified using Medicare claims; ESRD treatment information was obtained from ESRD registration during 2 yr of follow-up. Our cohort of 233,803 patients were hospitalized in 2000, were aged > or = 67 yr on discharge, did not have previous ESRD or AKI, and were Medicare-entitled for > or = 2 yr before discharge. In this cohort, 3.1% survived to discharge with a diagnosis of AKI, and 5.3 per 1000 developed ESRD. Among patients who received treatment for ESRD, 25.2% had a previous history of AKI. After adjustment for age, gender, race, diabetes, and hypertension, the hazard ratio for developing ESRD was 41.2 (95% confidence interval [CI] 34.6 to 49.1) for patients with AKI and CKD relative to those without kidney disease, 13.0 (95% CI 10.6 to 16.0) for patients with AKI and without previous CKD, and 8.4 (95% CI 7.4 to 9.6) for patients with CKD and without AKI. In summary, elderly individuals with AKI, particularly those with previously diagnosed CKD, are at significantly increased risk for ESRD, suggesting that episodes of AKI may accelerate progression of renal disease.

Race and end-stage renal disease in the United States Medicare population: the disparity persists.

AIM: A marked preponderance of end-stage renal disease among African Americans was described more than two decades ago. The objective of this study was to determine whether racial disparities in end-stage renal disease in the United States have changed over time. METHODS: The authors compared renal replacement therapy rates in five biennial cohorts (1993-1994, 1995-1996, 1997-1998, 1999-2000, 2001-2002; n = 6 315 283), using annual random samples of 5% of the US Medicare population and the United States Renal Data System registry. RESULTS: The proportion of African American subjects rose from 8.8% in the first cohort to 9.4% in the last. Renal replacement therapy rates (per 1000 patient-years) among white Americans in successive cohorts were 0.84, 0.96, 1.08, 1.16 and 1.20, compared with 2.98, 3.24, 3.65, 3.80 and 3.57 among African Americans (P < 0.0001 for race comparison within each biennial cohort). Corresponding hazards ratios, adjusted for demographic characteristics and comorbid conditions, were 2.01 (95% confidence interval 1.82-2.33), 1.96 (1.78-2.17), 2.00 (1.81-2.20), 2.01 (1.83-2.21) and 1.86 (1.69-2.04), suggesting the absence of meaningful reduction in racial disparities in renal replacement therapy rates over time. CONCLUSION: Disparities in renal replacement therapy rates between white and African American Medicare beneficiaries have persisted over time.

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.

Incidence and mortality of acute renal failure in Medicare beneficiaries, 1992 to 2001.

This study's objective was to determine the incidence and mortality of acute renal failure (ARF) in Medicare beneficiaries. Data were from hospitalized Medicare beneficiaries (5,403,015 discharges) between 1992 and 2001 from the 5% sample of Medicare claims. For 1992 to 2001, the overall incidence rate of ARF was 23.8 cases per 1000 discharges, with rates increasing by approximately 11% per year. Older age, male gender, and black race were strongly associated (P < 0.0001) with ARF. The overall in-hospital death rate was 4.6% in discharges without ARF, 15.2% in discharges with ARF coded as the principal diagnosis, and 32.6% in discharges with ARF as a secondary diagnosis. In-hospital death rates were 32.9% in discharges with ARF that required renal dialysis and 27.5% in those with ARF that did not require dialysis. Death within 90 d after hospital admission was 13.1% in discharges without ARF, 34.5% in discharges with ARF coded as the principal diagnosis, and 48.6% in discharges with ARF as a secondary diagnosis. Discharges with ARF were more (P < 0.0001) likely to have intensive care and other acute organ dysfunction than those without ARF. For discharges both with and without ARF, rates for death within 90 d after hospital admission showed a declining trend. In conclusion, the incidence rate of ARF in Medicare beneficiaries has been increasing. Those of older age, male gender, and black race are more likely to have ARF. These data show ARF to be a major contributor to morbidity and mortality in hospitalized patients.

Projecting the number of patients with end-stage renal disease in the United States to the year 2015.

The size of the prevalent ESRD population in the United States increased dramatically during the 1990s, from 196,000 in 1991 to 382,000 in 2000. Incidence also increased considerably during the same period, from 53,000 to 93,000 per year. If previous trends in ESRD incidence and prevalence continue, then current levels of health care resources that are devoted to the care of these patients will eventually be unable to meet the demand. This study discusses a Markov model developed to predict ESRD incidence, prevalence, and mortality to the year 2015 and incorporating expected changes in age/race distributions, diabetes prevalence, ESRD incidence, and probability of death. The model predicted that by 2015 there will be 136,166 incident ESRD patients per year (lower/upper limits 110,989 to 164,550), 712,290 prevalent patients (595,046 to 842,761), and 107,760 ESRD deaths annually (96,068 to 118,220). Incidence and prevalence counts are expected to increase by 44 and 85%, respectively, from 2000 to 2015 and incidence and prevalence rates per million population by 32 and 70%, respectively. The financial and human resources that will be needed to care for these patients in 2015 will be considerably greater than in 2005.

Epidemic of end-stage renal disease in people with diabetes in the United States population: do we know the cause?

BACKGROUND: The number of individuals initiating renal replacement therapy in the United States population grew exponentially over the past two decades. Cases of end-stage renal diseae (ESRD) attributed to diabetes accounted for most of this increase. In this report we examined factors that may account for the increase to determine whether it truly represents an epidemic of ESRD due to diabetes. METHODS: We reviewed time trends in data of the United States Renal Data system, the Diabetes Surveillance Program of the Centers for Disease Control and Prevention, and diabetes literature. RESULTS: Recent growth of the number of individuals with diabetes accounted for less than 10% of the increase in the number of diabetes-related ESRD. Instead, most of it was due to a threefold increase in risk of ESRD in people with diabetes and, therefore, qualifies as an epidemic. Curiously, this epidemic occurred despite widening implementation of effective renoprotective therapies. Individuals with type 2 diabetes, regardless of gender, age, or race, experienced the greatest increase in risk. There is no evidence that diabetic patients have been surviving longer, so the increased risk was not attributable to the high risk associated with long duration diabetes. CONCLUSION: We hypothesize that an epidemic of ESRD has occurred in people with diabetes in the United States population over the last two decades. The nature of the factor responsible for the epidemic and the reasons it affects patients with type 2 diabetes particularly are unknown. Research efforts to identify the putative factor deserve high priority, as does a commitment of resources to provide care for the burgeoning number of patients with ESRD and type 2 diabetes.

Association of heart disease with diabetes and hypertension in patients with ESRD.

BACKGROUND: No published study has reported the combined effect of diabetes and hypertension on heart disease in patients with renal failure. We determined this effect by using data for all US adults who started renal replacement therapy from 1995 to 1999. METHODS: Data for patient characteristics, diabetes, hypertension, and heart disease were collected from the Medical Evidence Report, on which 6 cardiac conditions were recorded: congestive heart failure, ischemic heart disease, myocardial infarction, cardiac arrest, cardiac arrhythmia, and pericarditis. On the basis of diabetic-hypertensive status, we categorized patients into 4 groups: diabetes only, hypertension only, both diabetes and hypertension, and neither diabetes nor hypertension. Adjusting for age, sex, race-ethnicity, and incidence year with logistic regression, we estimated the likelihood of heart disease according to diabetic-hypertensive status. RESULTS: Of 373,539 patients, 49.8% had diabetes and 75.8% had hypertension; 11.4% had diabetes only, 37.4% had hypertension only, 38.4% had both diabetes and hypertension, and 12.8% had neither diabetes nor hypertension. Approximately 44% of patients (n = 163,570) had at least 1 condition, 19.4% had at least 2 conditions, and 6.5% had at least 3 of the 6 cardiac conditions. Logistic regression indicated that patients with diabetes only and hypertension only were 3.1 and 2.8 times more likely ( P < 0.0001) to have heart disease than those without diabetes and hypertension, respectively. Patients with both diabetes and hypertension were 5.9, 5.0, and 4.8 times more likely (P < 0.0001) to have at least 1, at least 2, and at least 3 cardiac conditions than those with neither diabetes nor hypertension, respectively. CONCLUSION: Patients with renal failure with both diabetes and hypertension are more likely to have heart disease than those with diabetes only and hypertension only.

Does predialysis nephrology care influence patient survival after initiation of dialysis?

BACKGROUND: Early nephrology referral of patients with chronic kidney disease (CKD) has been suggested to reduce mortality after initiation of dialysis. This retrospective cohort study of incident dialysis patients between 1995 and 1998 was performed to address the association between frequency of nephrology care during the 24 months before initiation of dialysis and first-year mortality after initiation of dialysis. METHODS: Patient data were obtained from the Centers for Medicare & Medicaid Services. Patients who started dialysis between 1995 and 1998, and were Medicare-eligible for at least 24 months before initiation of dialysis, were included. One or more nephrology visits during a month was considered a month of nephrology care (MNC). RESULTS: Of the total 109,321 patients, only 50% had received nephrology care during the 24 months before initiation of dialysis. Overall, first-year mortality after initiation of dialysis was 36%. Cardiac disease was the major cause of mortality (46%). After adjusting for comorbidity, higher mortality was associated with increasing age (HR, 1.04 per year increase; 95% CI, 1.03 to 1.04) and more frequent visits to generalists (HR, 1.009 per visit increase; 95% CI, 1.003 to 1.014) and specialists (HR, 1.012 per visit increase; 95% CI, 1.011 to 1.013). Compared to patients with >/=3 MNC in the six months before initiation of dialysis, higher mortality was observed among those with no MNC during the 24 months before initiation of dialysis (HR, 1.51; 95% CI, 1.45 to 1.58), no MNC during the six months before initiation of dialysis (HR, 1.28; 95% CI, 1.20 to 1.36), and one or two MNC during the six months before initiation of dialysis (HR, 1.23; 95% CI, 1.18 to 1.29). CONCLUSION: Nephrology care before dialysis is important, and consistency of care in the immediate six months before dialysis is a predictor of mortality. Consistent nephrology care may be more important than previously thought, particularly because the frequency and severity of CKD complications increase as patients approach dialysis.

The association of initial hemodialysis access type with mortality outcomes in elderly Medicare ESRD patients.

BACKGROUND: Dialysis access is critical for therapy delivery. Few studies have linked type of dialysis access to patient survival in the elderly population. METHODS: We included 1995 to 1997 incidence Medicare hemodialysis patients (N = 66,595) who were 67 years and older at dialysis therapy initiation. Medicare Physician/Supplier claims were used to determine initial access type: simple fistula, autologous vein graft, synthetic graft, and hemodialysis catheter. We used International Classification of Diseases, Ninth Revision, Clinical Modification, codes to determine vascular access placement for renal failure. A Cox regression analysis assessed risk for death within 1 year, with explanatory variables of incidence year, age, sex, race, diabetes, initial access type, body mass index, days from first access placement date to initial dialysis date, and serum albumin, creatinine, and blood urea nitrogen levels. RESULTS: One-year crude death rates were 24.9%, 27.2%, 28.1%, and 41.5% for patients with simple fistulae, autologous vein grafts, synthetic grafts, and hemodialysis catheters, respectively. Patients with simple fistulae (the reference) had the lowest (P < 0.0001) likelihood of death compared with those with synthetic grafts (hazard ratio [HR], 1.160; 95% confidence interval [CI], 1.084 to 1.241) or catheters (HR, 1.696; 95% CI, 1.593 to 1.806). No difference (P > 0.09) in mortality risk was detected between simple fistulae and autologous vein grafts or between autologous vein grafts and synthetic grafts. CONCLUSION: In the US Medicare dialysis population, type of initial hemodialysis access was associated with 1-year mortality. Mortality risks were (in ascending order) fistulae, grafts, and catheters.

Anemia treatment in the pre-ESRD period and associated mortality in elderly patients.

BACKGROUND: Anemia is a common complication of advancing chronic kidney disease, yet little is known about the consistency of anemia treatment before end-stage renal disease (ESRD) and mortality on dialysis therapy. METHODS: We studied 89,193 incident Medicare patients with ESRD in 1995 to 1997 aged 67 plus years with claims 2 years before their dialysis therapy initiation. Patients were classified as follows: no epoetin, 25% or less (least consistent), greater than 25% to 50%, greater than 50% to 75%, and greater than 75% (most consistent) epoetin treatment in the available months from the first pre-ESRD epoetin dose to the first ESRD service date. Cox regression modeled the risk for 1-year death in the post-ESRD period, adjusting for age, sex, race, diabetic status, albumin level, and incidence year. RESULTS: Sixty percent of patients had hematocrits less than 30% at ESRD initiation, yet only 15.6% (N = 13,877) had epoetin claims before ESRD. The most consistent epoetin treatment group had hematocrits increase from 27.5% to 30.8% (P < 0.0001) by month 4 of treatment. Patients with the most consistent epoetin treatment had a greater mean hematocrit (29.2% +/- 0.11%; P < 0.0001) and albumin level (3.31 +/- 0.01 g/dL [33.1 g/L]) at initiation than those with the least consistent treatment (28.1% +/- 0.10% and 3.21 +/- 0.01 g/dL [32.1 g/L], respectively). The relative risk for death in patients with the least consistent versus the most consistent (the reference) epoetin treatment was 1.460 (95% CI, 1.245 to 1.713; P < 0.0001) 1 year after the first ESRD service date. CONCLUSION: Elderly patients with consistent pre-ESRD epoetin treatment had lower risks for death in the first year of dialysis therapy after ESRD initiation.

Effect of seminal plasma concentration and various extenders on postthaw motility and glass wool-Sephadex filtration of cryopreserved stallion semen.

OBJECTIVE: To compare the effect of semen extender and seminal plasma on postthaw motility and filtration through a glass wool-Sephadex (GWS) filter for frozen stallion semen. SAMPLE POPULATION: 7 stallions from which we collected > or = 3 ejaculates/stallion. PROCEDURES: 4 experiments were conducted to evaluate postthaw quality of frozen stallion semen. Kenney extender was compared with glucose-EDTA extender by use of various dilution rates that resulted in differing concentrations of seminal plasma. Stallions known to produce semen with poor postthaw quality were used to investigate whether a particular extender or dilution rate could improve ability of such semen to survive freeze-thaw procedures. RESULTS: Use of Kenney extender as the centrifugation extender significantly improved postthaw motility and GWS filtration, compared with glucose-EDTA. Extending semen at a dilution of 1:3 was significantly better than 1:1 for both motility and GWS filtration. In addition, including seminal plasma at a concentration of 5% in the cryopreserved semen resulted in significantly higher yield of spermatozoa after GWS filtration, compared with complete removal of SP or use of seminal plasma at 25%. Lastly, semen with poor postthaw quality had significantly improved postthaw quality in regard to motility and GWS filtration when semen was frozen with seminal plasma at a concentration of 5%, compared with semen frozen with seminal plasma at a concentration of 25%. CONCLUSIONS AND CLINICAL RELEVANCE: Use of Kenney extender at a high dilution (> or = 1:3) immediately after collection of semen can improve postthaw quality of frozen stallion semen.

A prospective, randomized comparison of the metabolic effects of pioglitazone or rosiglitazone in patients with type 2 diabetes who were previously treated with troglitazone.

OBJECTIVE: To characterize potential differences in glycemic control, plasma lipid level, and weight in a cohort of patients previously treated with troglitazone (TROG) who were switched to either pioglitazone or rosiglitazone. RESEARCH DESIGN AND METHODS: After a 2-week washout from TROG, 186 patients were randomly assigned to receive either pioglitazone (PIO) or rosiglitazone (ROSI). Weight, HbA(1c), and fasting lipid profile were documented before discontinuing TROG and at 4 months after starting either pioglitazone or rosiglitazone. Secondarily, the effect of concurrent medications on study outcomes was assessed. RESULTS: A total of 127 patients completed follow-up: 67 individuals in the PIO group (32 women, 35 men) and 60 individuals in the ROSI group (33 women, 27 men). There were no significant differences in gender mix, age, weight, fasting lipid profile, or HbA(1c) between the ROSI and PIO groups. After 4 months of randomized treatment, no change in HbA(1c) from baseline between or within groups was noted. Both groups experienced an equal and significant increase in weight from baseline of approximately 2.0 kg. Thiazolidinedione and HMG-CoA reductase inhibitor therapy had significant and independent effects on lipid profile (P < 0.005). Significant improvements in lipid profile were noted in the PIO group (P < 0.01), whereas none were detected with conversion to ROSI. Specifically, the PIO group experienced an average decrease in total cholesterol of approximately 20 mg/dl. CONCLUSIONS: Differing effects on lipid profile were apparent after random conversion from TROG to either PIO or ROSI, despite similar weight increase and glycemic control. The clinical significance of these differences remains to be determined, and further comparative research is warranted.

Peritoneal and hemodialysis: I. Differences in patient characteristics at initiation.

BACKGROUND: Comparisons of mortality outcomes between peritoneal dialysis (PD) and hemodialysis (HD) patients have shown varying results, which may be caused by the unequally distributed clinical conditions of patients at initiation. To address this issue, we evaluated the clinical characteristics of 105,954 patients at the initiation of PD and HD, using the U.S. national incidence data on treated end-stage renal disease from the Medical Evidence Form, 1995 to 1997. METHODS: A general linear model was used to analyze differences of age, albumin, creatinine, blood urea nitrogen (BUN), and hematocrit; categorical data analysis to evaluate body mass index (BMI), grouped into four categories: < 19, 19-25 (< 25), 25-30 (< 30), and 30+; and logistic regression to assess the likelihood of initiating PD versus HD. Diabetics (DM) were analyzed separately from non-diabetics (NDM). Explanatory variables in the logistic regression included incidence year, race, gender, age, BMI, albumin, creatinine, BUN, and hematocrit. Race included white and black. Age was categorized into four groups: 20-44, 45-64, 65-74, and 75+. RESULTS: At the initiation of dialysis PD patients were approximately 6 years younger (P < 0.0001) than HD patients. PD patients also had higher (P < 0.0001) albumin (+0.35 g/dL for DM and +0.23 g/dL for NDM) and hematocrit (+1.64% for DM and +1.71% for NDM) levels, and lower (P < 0.04) BUN (-8.75 mg/dL for DM and -5.24 mg/dL for NDM) and creatinine (-0.51 mg/dL for DM and -0.23 mg/dL for NDM) levels than HD patients. Whites had a higher (P < 0.0001) likelihood of starting PD than blacks, and patients with BMI <19 had a lower (P < 0.0001) chance of beginning on PD. CONCLUSION: PD patients had favorable clinical conditions at the initiation of dialysis, which should be taken into consideration when comparing dialysis outcomes between the two modalities.

Peritoneal and hemodialysis: II. Mortality risk associated with initial patient characteristics.

BACKGROUND: Patients initiating with peritoneal dialysis (PD) have favorable clinical conditions compared with hemodialysis (HD) patients, which may contribute to the varying results found in studies of mortality across the two therapies. METHODS: National incidence data of end-stage renal disease patients from 1995 to 1997 were used, excluding the first 90 days of treatment and including all patients who were on either PD or HD on day 91. Patients were then followed for a one-year period. A Cox proportional hazards regression analysis was used, separating diabetics and non-diabetics, and two statistical models were applied. Model 1 included race, gender, age, initial modality, and incidence year as explanatory variables. Model 2 added body mass index (BMI), initial levels of serum albumin, creatinine, and blood urea nitrogen. RESULTS: Age was most highly associated with mortality, followed by biochemical variables, BMI, gender, and dialysis modality. In diabetics, the hazard ratio (HR) from Model 1 indicated no difference [1.046, 95% confidence limits (CL) 0.989-1.105; P> 0.1, HD was the reference] in mortality between PD and HD, while Model 2 demonstrated that PD patients had a 13.4% (1.134, CL 1.072-1.100, P < 0.0001) higher chance of death. In non-diabetics, hazard ratios (HRs) from Models 1 and 2 indicated that PD patients had a 23.5% (0.765, 0.722-0.812, P < 0.0001) and 11.9% (0.881, 0.30-0.935, P < 0.0001), respectively, lower likelihood of death than HD patients. CONCLUSION: Our study indicates that the results changed depending on the analytical methods used. We recommend that, due to the unequally distributed clinical conditions of patients at initiation, comparisons of mortality outcomes between dialysis modalities should be made with caution.

Forecast of the number of patients with end-stage renal disease in the United States to the year 2010.

As the United States end-stage renal disease (ESRD) program enters the new millennium, the continued growth of the ESRD population poses a challenge for policy makers, health care providers, and financial planners. To assist in future planning for the ESRD program, the growth of patient numbers and Medicare costs was forecasted to the year 2010 by modeling of historical data from 1982 through 1997. A stepwise autoregressive method and exponential smoothing models were used. The forecasting models for ESRD patient numbers demonstrated mean errors of -0.03 to 1.03%, relative to the observed values. The model for Medicare payments demonstrated -0.12% mean error. The R(2) values for the forecasting models ranged from 99.09 to 99.98%. On the basis of trends in patient numbers, this forecast projects average annual growth of the ESRD populations of approximately 4.1% for new patients, 6.4% for long-term ESRD patients, 7.1% for dialysis patients, 6.1% for patients with functioning transplants, and 8.2% for patients on waiting lists for transplants, as well as 7.7% for Medicare expenditures. The numbers of patients with ESRD in 2010 are forecasted to be 129,200 +/- 7742 (95% confidence limits) new patients, 651,330 +/- 15,874 long-term ESRD patients, 520,240 +/- 25,609 dialysis patients, 178,806 +/- 4349 patients with functioning transplants, and 95,550 +/- 5478 patients on waiting lists. The forecasted Medicare expenditures are projected to increase to $28.3 +/- 1.7 billion by 2010. These projections are subject to many factors that may alter the actual growth, compared with the historical patterns. They do, however, provide a basis for discussing the future growth of the ESRD program and how the ESRD community can meet the challenges ahead.