Paul W. Eggers

Effects of race and income on mortality and use of services among Medicare beneficiaries.

BACKGROUND There are wide disparities between blacks and whites in the use of many Medicare services. We studied the effects of race and income on mortality and use of services. METHODS We linked 1990 census data on median income according to ZIP Code with 1993 Medicare administrative data for 26.3 million beneficiaries 65 years of age or older (24.2 million whites and 2.1 million blacks). We calculated age-adjusted mortality rates and age- and sex-adjusted rates of various diagnoses and procedures according to race and income and computed black:white ratios. The 1993 Medicare Current Beneficiary Survey was used to validate the results and determine rates of immunization against influenza. RESULTS For mortality, the black:white ratios were 1.19 for men and 1.16 for women (P<0.001 for both). For hospital discharges, the ratio was 1.14 (P<0.001), and for visits to physicians for ambulatory care it was 0.89 (P<0.001). For every 100 women, there were 26.0 mammograms among whites and 17.1 mammograms among blacks. As compared with mammography rates in the respective most affluent group, rates in the least affluent group were 33 percent lower among whites and 22 percent lower among blacks. The black:white rate ratio was 2.45 for bilateral orchiectomy and 3.64 for amputations of all or part of the lower limb (P<0.001 for both). For every 1000 beneficiaries, there were 515 influenza immunizations among whites and 313 among blacks. As compared with immunization rates in the respective most affluent group, rates in the least affluent group were 26 percent lower among whites and 39 percent lower among blacks. Adjusting the mortality and utilization rates for differences in income generally reduced the racial differences, but the effect was relatively small. CONCLUSIONS Race and income have substantial effects on mortality and use of services among Medicare beneficiaries. Providing health insurance is not enough to ensure that the program is used effectively and equitably by all beneficiaries.

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.

Chronic Kidney Disease Awareness, Prevalence, and Trends among U.S. Adults, 1999 to 2000

The incidence of kidney failure treatment in the United States increased 57% from 1991 to 2000. Chronic kidney disease (CKD) prevalence was 11% among U.S. adults surveyed in 1988 to 1994. The objective of this study was to estimate awareness of CKD in the U.S. population during 1999 to 2000 and to determine whether the prevalence of CKD in the United States increased compared with 1988 to 1994. Analysis was conducted of nationally representative samples of noninstitutionalized adults, aged 20 yr and older, in two National Health and Nutrition Examination Surveys conducted in 1988 to 1994 (n = 15,488) and 1999 to 2000 (n = 4101) for prevalence +/- SE. Awareness of CKD is self-reported. Kidney function (GFR), kidney damage (microalbuminuria or greater), and stages of CKD (GFR and albuminuria) were estimated from calibrated serum creatinine, spot urine albumin to creatinine ratio (ACR), age, gender, and race. GFR was estimated using the simplified Modification of Diet in Renal Disease Study equation. Self-reported awareness of weak or failing kidneys in 1999 to 2000 was strongly associated with decreased kidney function and albuminuria but was low even in the presence of both conditions. Only 24.3 +/- 6.4% of patients at GFR 15 to 59 ml/min per 1.73 m(2) and albuminuria were aware of CKD compared with 1.1 +/- 0.3% at GFR of 90 ml/min per 1.73 m(2) or greater and no microalbuminuria. At moderately decreased kidney function (GFR 30 to 59 ml/min per 1.73 m(2)), awareness was much lower among women than men (2.9 +/- 1.6 versus 17.9 +/- 5.9%; P = 0.008). The prevalence of moderately or severely decreased kidney function (GFR 15 to 59 ml/min per 1.73 m(2)) remained stable over the past decade (4.4 +/- 0.3% in 1988 to 1994 and 3.8 +/- 0.4% in 1999 to 2000; P = 0.23). At the same time, the prevalence of albuminuria (ACR >/= 30 mg/g) in single spot urine increased from 8.2 +/- 0.4% to 10.1 +/- 0.7% (P = 0.01). Overall CKD prevalence was similar in both surveys (9% using ACR > 30 mg/g for persistent microalbuminuria; 11% in 1988 to 1994 and 12% in 1999 to 2000 using gender-specific ACR cutoffs). Despite a high prevalence, CKD awareness in the U.S. population is low. In contrast to the dramatic increase in treated kidney failure, overall CKD prevalence in the U.S. population has been relatively stable.

In-center hemodialysis six times per week versus three times per week

BACKGROUND In this randomized clinical trial, we aimed to determine whether increasing the frequency of in-center hemodialysis would result in beneficial changes in left ventricular mass, self-reported physical health, and other intermediate outcomes among patients undergoing maintenance hemodialysis. METHODS Patients were randomly assigned to undergo hemodialysis six times per week (frequent hemodialysis, 125 patients) or three times per week (conventional hemodialysis, 120 patients) for 12 months. The two coprimary composite outcomes were death or change (from baseline to 12 months) in left ventricular mass, as assessed by cardiac magnetic resonance imaging, and death or change in the physical-health composite score of the RAND 36-item health survey. Secondary outcomes included cognitive performance; self-reported depression; laboratory markers of nutrition, mineral metabolism, and anemia; blood pressure; and rates of hospitalization and of interventions related to vascular access. RESULTS Patients in the frequent-hemodialysis group averaged 5.2 sessions per week; the weekly standard Kt/V(urea) (the product of the urea clearance and the duration of the dialysis session normalized to the volume of distribution of urea) was significantly higher in the frequent-hemodialysis group than in the conventional-hemodialysis group (3.54±0.56 vs. 2.49±0.27). Frequent hemodialysis was associated with significant benefits with respect to both coprimary composite outcomes (hazard ratio for death or increase in left ventricular mass, 0.61; 95% confidence interval [CI], 0.46 to 0.82; hazard ratio for death or a decrease in the physical-health composite score, 0.70; 95% CI, 0.53 to 0.92). Patients randomly assigned to frequent hemodialysis were more likely to undergo interventions related to vascular access than were patients assigned to conventional hemodialysis (hazard ratio, 1.71; 95% CI, 1.08 to 2.73). Frequent hemodialysis was associated with improved control of hypertension and hyperphosphatemia. There were no significant effects of frequent hemodialysis on cognitive performance, self-reported depression, serum albumin concentration, or use of erythropoiesis-stimulating agents. CONCLUSIONS Frequent hemodialysis, as compared with conventional hemodialysis, was associated with favorable results with respect to the composite outcomes of death or change in left ventricular mass and death or change in a physical-health composite score but prompted more frequent interventions related to vascular access. (Funded by the National Institute of Diabetes and Digestive and Kidney Diseases and others; ClinicalTrials.gov number, NCT00264758.).

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.

Acute Kidney Injury and Chronic Kidney Disease as Interconnected Syndromes

For more than 40 years, nephrologists have classified diminished kidney function as two distinct syndromes — acute and chronic kidney failure. Whereas chronic kidney disease was recognized in the 19th century, acute renal dysfunction became evident during the London Blitz of World War II, with the realization that crush injuries could cause dramatic but often reversible cessation of renal function. The disease states and stages of both acute and chronic renal syndromes are delineated according to the serum creatinine concentration or the glomerular filtration rate (GFR), functional markers that were identified in the early 20th century. 1 Advanced renal impairment in both syndromes is treated with dialysis. During the past decade, separate conceptual models for chronic kidney disease 2 and acute kidney injury 3 were developed to facilitate organized approaches to clinical research and trials. However, recent epidemiologic and mechanistic studies suggest that the two syndromes are not distinct entities but rather are closely interconnected — chronic kidney disease is a risk factor for acute kidney injury, acute kidney injury is a risk factor for the development of chronic kidney disease, and both acute kidney injury and chronic kidney disease are risk factors for cardiovascular disease (Fig. 1). 4

Comparative Performance of the CKD Epidemiology Collaboration (CKD-EPI) and the Modification of Diet in Renal Disease (MDRD) Study Equations for Estimating GFR Levels Above 60 mL/min/1.73 m2

BACKGROUND The Modification of Diet in Renal Disease (MDRD) Study equation underestimates measured glomerular filtration rate (GFR) at levels>60 mL/min/1.73 m2, with variable accuracy among subgroups; consequently, estimated GFR (eGFR)>or=60 mL/min/1.73 m2 is not reported by clinical laboratories. Here, performance of a more accurate GFR-estimating equation, the Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) equation, is reported by level of GFR and clinical characteristics. STUDY DESIGN Test of diagnostic accuracy. SETTING & PARTICIPANTS Pooled data set of 3,896 people from 16 studies with measured GFR (not used for the development of either equation). Subgroups were defined by eGFR, age, sex, race, diabetes, prior solid-organ transplant, and body mass index. INDEX TESTS eGFR from the CKD-EPI and MDRD Study equations and standardized serum creatinine. REFERENCE TEST Measured GFR using urinary or plasma clearance of exogenous filtration markers. RESULTS Mean measured GFR was 68+/-36 (SD) mL/min/1.73 m2. For eGFR<30 mL/min/1.73 m2, both equations have similar bias (median difference compared with measured GFR). For eGFR of 30-59 mL/min/1.73 m2, bias was decreased from 4.9 to 2.1 mL/min/1.73 m2 (57% improvement). For eGFR of 60-89 mL/min/1.73 m2, bias was decreased from 11.9 to 4.2 mL/min/1.73 m2 (61% improvement). For eGFR of 90-119 mL/min/1.73 m2, bias was decreased from 10.0 to 1.9 mL/min/1.73 m2 (75% improvement). Similar or improved performance was noted for most subgroups with eGFR<90 mL/min/1.73 m2, other than body mass index<20 kg/m2, with greater variation noted for some subgroups with eGFR>or=90 mL/min/1.73 m2. LIMITATIONS Limited number of elderly people and racial and ethnic minorities with measured GFR. CONCLUSIONS The CKD-EPI equation is more accurate than the MDRD Study equation overall and across most subgroups. In contrast to the MDRD Study equation, eGFR>or=60 mL/min/1.73 m2 can be reported using the CKD-EPI equation.

The effects of frequent nocturnal home hemodialysis: the Frequent Hemodialysis Network Nocturnal Trial

Prior small studies have shown multiple benefits of frequent nocturnal hemodialysis compared to conventional three times per week treatments. To study this further, we randomized 87 patients to three times per week conventional hemodialysis or to nocturnal hemodialysis six times per week, all with single-use high-flux dialyzers. The 45 patients in the frequent nocturnal arm had a 1.82-fold higher mean weekly stdKt/V(urea), a 1.74-fold higher average number of treatments per week, and a 2.45-fold higher average weekly treatment time than the 42 patients in the conventional arm. We did not find a significant effect of nocturnal hemodialysis for either of the two coprimary outcomes (death or left ventricular mass (measured by MRI) with a hazard ratio of 0.68, or of death or RAND Physical Health Composite with a hazard ratio of 0.91). Possible explanations for the left ventricular mass result include limited sample size and patient characteristics. Secondary outcomes included cognitive performance, self-reported depression, laboratory markers of nutrition, mineral metabolism and anemia, blood pressure and rates of hospitalization, and vascular access interventions. Patients in the nocturnal arm had improved control of hyperphosphatemia and hypertension, but no significant benefit among the other main secondary outcomes. There was a trend for increased vascular access events in the nocturnal arm. Thus, we were unable to demonstrate a definitive benefit of more frequent nocturnal hemodialysis for either coprimary outcome.

Effect of transplantation on the medicare end-stage renal disease program

The Medicare end-stage renal disease program has received considerable attention as a model of government funding for high-cost medical treatment. This paper examines how the program has been influenced by renal transplantation. In the past decade, the number of kidney transplantations has increased substantially, and the success rate of these procedures has improved. From 1980 to 1985, the number of transplantations increased by 10 percent per year. During that time, the survival rates for grafts from cadavers and living related donors increased by 7 and 3 percent, respectively, in part because of the introduction of cyclosporine. As a result, the fastest-growing group of beneficiaries of the Medicare end-stage renal disease program are those with functioning grafts. As of the end of 1985, these patients accounted for 18 percent of all beneficiaries and 32 percent of all beneficiaries less than 55 years of age. In the youngest groups, transplantation has reached a level sufficient to reduce the absolute numbers of patients on dialysis, beginning in 1983. Increases in transplantation are not evenly distributed among subgroups of beneficiaries. Relatively few patients 65 years of age and older receive transplants; blacks receive transplants at a rate roughly half that among whites, but the rate is increasing. Because the costs of maintaining patients with functioning grafts are only one third of those for patients on dialysis and because the quality of life is usually much better, renal transplantation is causing a convergence of the best clinical and economic outcomes for patients with end-stage renal disease.