Allan J. Collins

Poor long-term survival after acute myocardial infarction among patients on long-term dialysis.

BACKGROUND Cardiovascular disease is common in patients on long-term dialysis, and it accounts for 44 percent of overall mortality in this group. We undertook a study to assess long-term survival after acute myocardial infarction among patients in the United States who were receiving long-term dialysis. METHODS Patients on dialysis who were hospitalized during the period from 1977 to 1995 for a first myocardial infarction after the initiation of renal-replacement therapy were retrospectively identified from the U.S. Renal Data System data base. Overall mortality and mortality from cardiac causes (including all in-hospital deaths) were estimated by the life-table method. The effect of independent predictors on survival was examined in a Cox regression model with adjustment for existing illnesses. RESULTS The overall mortality (+/-SE) after acute myocardial infarction among 34,189 patients on long-term dialysis was 59.3+/-0.3 percent at one year, 73.0+/-0.3 percent at two years, and 89.9+/-0.2 percent at five years. The mortality from cardiac causes was 40.8+/-0.3 percent at one year, 51.8+/-0.3 percent at two years, and 70.2+/-0.4 percent at five years. Patients who were older or had diabetes had higher mortality than patients without these characteristics. Adverse outcomes occurred even in patients who had acute myocardial infarction in 1990 through 1995. Also, the mortality rate after myocardial infarction was considerably higher for patients on long-term dialysis than for renal-transplant recipients. CONCLUSIONS Patients on dialysis who have acute myocardial infarction have high mortality from cardiac causes and poor long-term survival.

Chronic Kidney Disease and the Risk for Cardiovascular Disease, Renal Replacement, and Death in the United States Medicare Population, 1998 to 1999

Knowledge of the excess risk posed by specific cardiovascular syndromes could help in the development of strategies to reduce premature mortality among patients with chronic kidney disease (CKD). The rates of atherosclerotic vascular disease, congestive heart failure, renal replacement therapy, and death were compared in a 5% sample of the United States Medicare population in 1998 and 1999 (n = 1,091,201). Patients were divided into the following groups: 1, no diabetes, no CKD (79.7%); 2, diabetes, no CKD (16.5%); 3, CKD, no diabetes (2.2%); and 4, both CKD and diabetes (1.6%). During the 2 yr of follow-up, the rates (per 100 patient-years) in the four groups were as follows: atherosclerotic vascular disease, 14.1, 25.3, 35.7, and 49.1; congestive heart failure, 8.6, 18.5, 30.7, and 52.3; renal replacement therapy, 0.04, 0.2, 1.6, and 3.4; and death, 5.5, 8.1, 17.7, and 19.9, respectively (P < 0.0001). With use of Cox regression, the corresponding adjusted hazards ratios were as follows: atherosclerotic vascular disease, 1, 1.30, 1.16, and 1.41 (P < 0.0001); congestive heart failure, 1, 1.44, 1.28, and 1.79 (P < 0.0001); renal replacement therapy, 1, 2.52, 23.1, and 38.9 (P < 0.0001); and death, 1, 1.21, 1.38, and 1.56 (P < 0.0001). On a relative basis, patients with CKD were at a much greater risk for the least frequent study outcome, renal replacement therapy. On an absolute basis, however, the high death rates of patients with CKD may reflect accelerated rates of atherosclerotic vascular disease and congestive heart failure.

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.

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.

Incidence and Mortality of Acute Renal Failure in Medicare Beneficiaries, 1992 to 2001

This studys 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.

End-Stage Renal Disease in the United States: An Update from the United States Renal Data System

Patients with ESRD consume a vastly disproportionate amount of financial and human resources. Approximately 0.03% of the US population began renal replacement therapy in 2004, an adjusted incidence rate of 339 per million. Declining incidence rates were observed for most primary causes of ESRD and in most major demographic categories; the worry is that rates of diabetic ESRD continue to rise in younger black adults. Although diabetes and hypertension remain the most commonly reported cause of ESRD, rates of end-stage atherosclerotic renovascular disease seem to be on the rise in older patients. Although clinical care indicators, such as the proportion of hemodialysis patients using fistulas, continue to improve gradually, the proportion of patients overshooting target hemoglobin levels under epoetin therapy may be a source of concern. Survival probabilities have improved steadily in the US ESRD population since the late 1980s, which is remarkable when one considers the ever-expanding burden of comorbidity in incident patients. However, although first-year dialysis mortality rates have clearly improved since 1987, meaningful improvements do not seem to have accrued since 1993, in contrast to steady annual improvements in years 2 through 5. Although most of these findings are grounds for cautious optimism, the same cannot be said for issues of cost; reflecting the growth in the size of the ESRD population, associated costs grew by 57% between 1999 and 2004 and now account for 6.7% of total Medicare expenditures.

Comparative Survival of Dialysis Patients in the United States After Coronary Angioplasty, Coronary Artery Stenting, and Coronary Artery Bypass Surgery and Impact of Diabetes

Background—The optimal method of coronary revascularization in dialysis patients is controversial. The purpose of this study was to compare the long-term survival of dialysis patients in the United States after PTCA, coronary stenting, or CABG. Methods and Results—Dialysis patients hospitalized from 1995 to 1998 for first coronary revascularization procedures after renal replacement therapy initiation were identified from the US Renal Data System database. All-cause and cardiac survival was estimated by the life-table method and compared by the log-rank test. The impact of independent predictors on survival was examined in a Cox regression model. The in-hospital mortality was 8.6% for 6668 CABG patients, 6.4% for 4836 PTCA patients, and 4.1% for 4280 stent patients. The 2-year all-cause survival (mean±SEM) was 56.4±1.4% for CABG patients, 48.2±1.5% for PTCA patients, and 48.4±2.0% for stent patients (P <0.0001). After comorbidity adjustment, the relative risk (RR) for CABG (versus PTCA) patients was 0.80 (95% CI 0.76 to 0.84, P <0.0001) for all-cause death and 0.72 (95% CI 0.67 to 0.77, P <0.0001) for cardiac death. For stent (versus PTCA) patients, the RR was 0.94 (95% CI 0.88 to 0.99, P =0.03) for all-cause death and 0.92 (95% CI 0.85 to 0.99, P =0.04) for cardiac death. In diabetic (versus PTCA) patients, the RR for CABG surgery was 0.81 (95% CI 0.75 to 0.88, P <0.0001) for all-cause death and 0.71 (95% CI 0.64 to 0.78, P <0.0001) for cardiac death, and the RR for the stent procedure was 0.99 (95% CI 0.91 to 1.08, P =NS) for all-cause death and 0.99 (95% CI 0.89 to 1.11, P =NS) for cardiac death. Conclusions—In this retrospective study, dialysis patients in the United States had better long-term survival after CABG surgery than after percutaneous coronary intervention. Stent outcomes were relatively worse in diabetic patients. Our data support the need for large clinical registries and prospective trials of surgical and percutaneous coronary revascularization procedures in dialysis patients.

Calcium, Phosphorus, Parathyroid Hormone, and Cardiovascular Disease in Hemodialysis Patients: The USRDS Waves 1, 3, and 4 Study

Animal studies suggest that calcium-phosphorus homeostatic abnormalities cause cardiovascular disease in uremia; few observational studies in humans have explored this. Associations in the retrospective United States Renal Data System Waves 1, 3, and 4 Study of 14,829 patients who were on hemodialysis on December 31, 1993, were examined. Mean age and duration of renal replacement therapy were 60.0 and 3.2 yr, respectively; 40.7% had diabetes. Quintiles (Q(1) to Q(5)) of (albumin-adjusted) calcium were </=8.7, 8.8 to 9.2, 9.3 to 9.6, 9.7 to 10.2, and >10.2 mg/dl; phosphorus, </=4.4, 4.5 to 5.3, 5.4 to 6.3, 6.4 to 7.5, and >7.5 mg/dl; calcium-phosphorus product, </=40.9, 41.0 to 50.1, 50.2 to 59.2, 59.3 to 71.0, and >71.0 mg(2)/dl(2); and parathyroid hormone (PTH), </=37, 38 to 99, 100 to 210, 211 to 480, and >480 pg/ml. Higher calcium levels were associated with fatal or nonfatal cardiovascular events (adjusted hazards ratio, 1.08 for Q(5), versus Q(1)) and all-cause mortality (Q(2), 1.07; Q(4), 1.11; Q(5), 1.14). Phosphorus levels were associated with cardiovascular events (Q(2), 1.06; Q(3), 1.13; Q(4), 1.14; Q(5), 1.25) and mortality (Q(4), 1.10; Q(5), 1.19), calcium-phosphorus product was associated with cardiovascular events (Q(3), 1.09; Q(4), 1.14; Q(5), 1.24) and mortality (Q(4), 1.09; Q(5), 1.19), and PTH levels were associated with cardiovascular events (Q(5), 1.12) and mortality (Q(5), 1.17). Despite limitations (including retrospective design; noncurrent study era; and lack of serial calcium, phosphorus, and PTH measurements), this study suggests that disorders of calcium homeostasis are associated with fatal and nonfatal cardiovascular events and all-cause mortality in hemodialysis patients.

Mortality risks of peritoneal dialysis and hemodialysis

Studies of outcomes associated with dialysis therapies have yielded conflicting results. Bloembergen et al showed that prevalent patients on continuous ambulatory peritoneal dialysis (CAPD) or continuous cycling peritoneal dialysis (CCPD) had a 19% higher mortality risk than hemodialysis patients, and Fenton et al, analyzing Canadian incident patients, found a 27% lower risk. Attempting to reconcile these differences, we evaluated incident Medicare patients (99,048 on hemodialysis, 18,110 on CAPD/CCPD) from 1994 through 1996, following up to June 30, 1997. Patients were followed to transplantation, death, loss to follow-up, 60 days after modality change, or end of the study period. For each 3-month survival period, we used an interval Poisson regression to compare death rates, adjusting for age, gender, race, and primary renal diagnosis. A Cox regression was used to evaluate cause-specific mortality, and proportionality was addressed in both regressions by separating diabetic and nondiabetic patients. The Poisson regressions showed CAPD/CCPD to have outcomes comparable with or significantly better than hemodialysis, although results varied over time. The Cox regression found a lower mortality risk in nondiabetic CAPD/CCPD patients (women younger than 55 years: risk ratio [RR] = 0. 61; Cl, 0.59 to 0.66; women age 55 years or older: RR = 0.87; Cl, 0. 84 to 0.91; men younger than 55 years: RR = 0.72; Cl, 0.67 to 0.77; men age 55 years or older: RR = 0.87; Cl, 0.83 to 0.92) and in diabetic CAPD/CCPD patients younger than 55 (women: RR = 0.88; Cl, 0. 82 to 0.94; men: RR = 0.86; Cl, 0.81 to 0.92). The risk of all-cause death for female diabetics 55 years of age and older, in contrast, was 1.21 (Cl, 1.17 to 1.24) for CAPD/CCPD, and in cause-specific analyses, these patients had a significantly higher risk of infectious death. We conclude that, overall, within the first 2 years of therapy, short-term CAPD/CCPD appears to be associated with superior outcomes compared with hemodialysis. It also appears that patients on the two therapies have different mortality patterns over time, a nonproportionality that makes survival analyses vulnerable to the length of follow-up. Further investigation is needed to evaluate both the potential explanations for these findings and the use of more advanced statistical methods in the analysis of mortality rates associated with these dialytic therapies.

Urea Index and Other Predictors of Hemodialysis Patient Survival

The mortality of dialysis patients in the United States has been a concern since the US Renal Data System 1989 report, which showed a lower survival rate in the United States compared with Europe. The differences were thought to be multifactorial, including case mix, malnutrition, and adequacy of dialysis. We reviewed the Regional Kidney Disease Programs 1976 to 1989 database for the pattern of co-morbidity, dialysis therapy, and low serum albumin in 1,082 nondiabetic and 691 diabetic patients followed to September 15, 1991. The number of patients over 60 years of age has increased by 15% to 20% per year since 1982. The primary renal diagnoses for nondiabetic patients have shifted from 26% glomerulonephritis, 18% vascular and hypertension, and 15% interstitial kidney disease cases during the period from 1976 to 1982 to 19% glomerulonephritis, 35% vascular and hypertension, and 10% interstitial disease cases during the period from 1986 to 1989. Co-morbidity as single and multiple conditions has increased from 66% to 85% in diabetic patients and from 57% to 66% in nondiabetic patients. The number of patients with two or more co-morbid conditions has increased 1.5-fold in nondiabetic patients and twofold in diabetic patients from the 1976 to 1982 period to the 1986 to 1989 period. Urea index and albumin were determined for these patients and were averaged as a risk factor. A Cox regression analysis was used to determine the relative risk of death of such characteristics as age, renal diagnosis, co-morbidity, urea index (KT/V), and albumin in nondiabetic and diabetic patients. Urea index was divided into ranges of less than 1.0 (mean, 0.9), 1.0 to less than 1.2, 1.2 to less than 1.4, and > or = 1.4 (mean, 1.6). The relative risk of death in nondiabetic patients was 0.65 (P = 0.0012) for KT/V 1.2 to less than 1.4 and 0.67 (P = 0.0029) for KT/V > or = 1.4 (mean, 1.6) compared with 1.0 to less than 1.2 as the baseline. In the diabetic patients, the relative risk of death was 0.70 (P = 0.009) for KT/V 1.2 to less than 1.4 and 0.59 (P = 0.0001) for KT/V > or = 1.4 (mean, 1.6) compared with 1.0 to less than 1.2. In the diabetic patients, KT/V > or = 1.4 also was significantly different from 1.2 to less than 1.4 as it impacted on death rates.(ABSTRACT TRUNCATED AT 400 WORDS)