Using the US Renal Data System (USRDS), a national registry for ESRD,3
we identified all patients aged 65 years or older who were first treated with long-term dialysis or kidney transplantation between June 1, 2005, and May 31, 2006, were of either black or white race, had complete information on baseline characteristics, and had Medicare coverage at onset of ESRD (N=41 420). Patients of other races were not included because there were too few to support stratified analyses.
The primary predictor variable for all analyses was each hospital referral region’s end-of-life expenditure index, which is a measure of intensity of care during the last 6 months of life.1
The index reflects both physician spending (from the Medicare Carrier File) and acute hospital spending (from the Medicare Provider Analysis and Review File) among Medicare beneficiaries who were between the ages of 65 and 100 years at the time of death. Only those who were eligible for Medicare for the 6-month period before death and were not enrolled in a health maintenance organization during this time were used to calculate the index. The index is calculated based on standardized national prices and is adjusted for the age, race, and sex of the Medicare beneficiaries in each hospital referral region. As such, it is intended to reflect that component of regional Medicare spending attributable to the overall quantity of medical services provided rather than to local differences in pricing and demographic structure. We obtained the most recent version of the end-of-life expenditure index (based on deaths occurring from 2000–2003) from the Dartmouth Atlas of Healthcare.6
Hospital referral regions were categorized by quintile of the end-of-life expenditure index.
Incident cases of treated ESRD (defined as first receipt of long-term dialysis or kidney transplant) over the 8-year period from January 1, 2000, through December 31, 2007, within each hospital referral region were identified using the USRDS’ Patients File based on zip code at the onset of ESRD. Denominator populations for each hospital referral region were identified using zip code data from the 2000 US Census. Using these 2 data sources, we calculated the crude average annual incidence of treated ESRD within each hospital referral region by age, race, and sex from 2000 through 2007.
The following measures of preparedness for ESRD were obtained from the USRDS’ Medical Evidence File: (1) receipt of care from a nephrologist before the onset of ESRD, (2) presence of optimal access for hemodialysis (ie, fistula vs graft or catheter), and (3) use of peritoneal dialysis (vs hemodialysis). Receipt of a kidney transplant as the initial treatment modality (preemptive transplant) was ascertained from the USRDS’ Patients File. Unlike hemodialysis, initial treatment of ESRD with either peritoneal dialysis or kidney transplant usually requires advance planning and is thus a marker of ESRD preparedness, with the caveat that not all patients will be eligible for or choose these modalities.
Information on end-of-life care practices was obtained from the USRDS’ Death File based on the report of the nephrologist (Centers for Medicare & Medicaid Services form 2746). Measures included whether dialysis was discontinued before death, whether the patient was receiving hospice care before death, and place of death (hospital vs home, dialysis unit, nursing home, or other).
Age at onset of ESRD, race, and sex were ascertained from the USRDS’ Patients File. The following characteristics were ascertained from the USRDS’ Medical Evidence File based on the report of the nephrologist at onset of ESRD (Centers for Medicare & Medicaid Services form 2728): (1) comorbid conditions, which included diabetes, coronary artery disease, peripheral arterial disease, stroke, congestive heart failure, chronic obstructive pulmonary disease, and cancer; (2) dual eligibility for Medicare and Medicaid; (3) clinical measures, which included each patient’s reported estimated glomerular filtration rate and body mass index (calculated as weight in kilograms divided by height in meters squared) at the onset of ESRD; (4) measures of functional status, which included whether patients needed assistance in activities of daily living, could ambulate, could transfer, and were living in a nursing home. The percentage of patients who died within 6 months of ESRD onset is also reported to provide a rough proxy measure for how sick patients were at the onset of ESRD, and is based on the date of death in the USRDS’ Patients File.
Patient characteristics, ESRD preparedness, and end-of-life care practices were described using means or proportions with 95% confidence intervals (CIs) and tests for trend across quintiles of the end-of-life expenditure index. For groups defined by age, race, and sex, the mean annual incidence of treated ESRD for hospital referral regions within each quintile of the end-of-life expenditure index was expressed as the number of cases of ESRD per 100 000 persons per year with 95% CIs. The ESRD incidence rate ratios with 95% CIs were calculated for the highest compared with the lowest quintile of the end-of-life expenditure index for groups defined by age, sex, and race.
Logistic regression analysis was used to describe the association of quintile of the end-of-life expenditure index with measures of ESRD preparedness. These analyses were adjusted for baseline patient characteristics. Logistic regression analysis also was used to measure the association of quintile of end-of-life expenditure index with end-of-life care practices among patients who died within 2 years of ESRD onset. These analyses were adjusted for baseline patient characteristics, receipt of care from a nephrologist, and treatment modality (hemodialysis, peritoneal dialysis, or transplant). Analyses of dialysis discontinuation excluded decedents who had received a kidney transplant. Significance testing was 2-sided and a P value of less than .05 was considered statistically significant. All analyses were conducted using Stata SE version 10.1 (Stata-Corp, College Station, Texas). The study was approved by the institutional review board at the University of Washington.