United States renal data system
United States Renal Data System (USRDS): an example of a public health information system that supports chronic disease management
INDICATIONS FOR CLINICAL DATA SYSTEM IN CHRONIC KIDNEY DISEASE:
According to 2007 Medicare data, as many as 2.9 million Medicare recipients have the diagnosis of chronic kidney disease (CKD). Estimates obtained from the National Health and Nutritional Examination Survey (NHANES), suggests 26.3 million (13.1%) of the general United States (US) population suffers from stages 1 to 4 of CKD. In addition, 527,233 individuals suffer from the most severe form of CKD, also referred to as end stage renal disease (ESRD) as of 2007 year end. Patients with ESRD require life sustaining dialysis therapy for survival. Wide adoption of dialysis therapy in the US began in 1972 after the formation of the ESRD program under Medicare with congressional passage of Section 299I of Public Law 92-603, which extended Medicare coverage to all citizens with qualifying work history regardless of age if they were to require dialysis therapy. The economic impact of ESRD treatment has grown in a disproportionate manner relative to the percentage of the general population that it represents; the ESRD sub-population consumed 5.8% (23.9 million) of total Medicare expenditure in 2007, while comprising only 0.18% of that population. Given its central role in funding of ESRD treatment via Medicare, the federal government was uniquely positioned and incentivized to collect data regarding optimal utilization of financial resources in ESRD care.
FORMATIONS OF THE UNITED STATES RENAL DATA SYSTEM:
Initially, the Health Care Financing Administration (HCFA) gathered information on Medicare beneficiaries that included entitlement, demographic, cost and utilization data. In 1988 a national ESRD registry was established via funding from the National Institute of Diabetes Digestive and Kidney Diseases (NIDDK) at the National Institute of Health (NIH), resulting in formation of the United State Renal Data System (USRDS). The first contract was awarded to the Urban Institute in Washington, DC, which subsequently collaborated with researchers at the University of Michigan Kidney Epidemiology and Cost Center (UM-KECC). In 1999 under a new contract from NIDDK/NIH, the USRDS was divided into a Coordinating Center (CC) and four Special Studies Centers (SSCs). The CC and Cardiovascular SCC were awarded to the Minneapolis Medical Research Foundation, while the Economic SSC was awared to the University of Iowa. A year later, a Nutrition SSC was established at the University of California San Francisco and a Quality of Life/Rehabilitaiton SSC was formed at Emory University. In 2007 a new seven year contract was renewed with all the SSCs remaining intact with the exception of the Economic SSC merging with the CC.
- characterize the ESRD population
- describe the prevalence and incidence of ESRD along with trends in mortality and disease rates
- investigate relationships among patient demographics, treatment modalities, and morbidity
- identify new areas for special renal studies and support investigator-initiated research
- provide data sets and samples of national data to support research by the Special Studies Centers
USRDS DATA SOURCE:
The origin source of data collected by the USRDS was Medicare claims information of covered ESRD patients from HCFA, which has since been renamed the Centers for Medicare and Medicaid Services (CMS) in 2001. For patients not covered by CMS, information from employer group health plans (EGHP) were added as an additional data sources. Data collected from the National Health and Nutrition Examination Survey (NHANES) was also incorporated for information about the pre-ESRD population. Kidney transplant data was also included, first via CMS sources and later deriving solely from the Organ Procurement and Transplantation Network (OPTN) and Scientific Registry of Transplant Recipients (SRTR) projects within the national transplant organization, United Network for Organ Sharing (UNOS).
USRDS DATA CONTENT AND HANDLING:
Data collection for the USRDS began with the mandatory HCFA/CMS 2728 Medical Evidence Report form, which all patients with ESRD starting outpatient dialysis on a chronic basis are required to complete. The original form collected basic demographic information, date of dialysis initiation, type of dialysis treatment, transplant status from Medicare covered patients only. In 1995, all dialysis patients were required to complete the 2728 form regardless of Medicare eligibility status. The subsequent 2728 forms also expanded the scope of information required to include basic laboratory data at dialysis initiation, primary cause of kidney failure, comorbid conditions, employment status, type of dialysis access available, use of erythropoietin pre-ESRD, duration of nephrologist and dietician care pre-ESRD and insurance status. Dialysis treatment facilities send the 2728 forms to one of 18 established regional ESRD networks. Each regional network then enters the data electronically to a central respository, Standard Information Management System (SIMS). The regional ESRD network SIMS is the data interface between dialysis facilities and the overall CMS ESRD data set called the the Program Management and Medical Information System respository (PMMIS), which can be accessed via an interactive tool called the Renal Beneficiary and Utilization System (REBUS). Due in part to data access problems with REBUS and the need for improved data quality and integration with different information systems, CMS replaced REBUS with a modernized Renal Management Information System (REMIS) in the fall of 2003. Additional data sources for PMMIS/REBUS are the Social Security Administration, UNOS and other internal data of CMS. ESRD mortality information are obtained by CMS from the mandatory CMS 2746 ESRD Death Notification form, which is also sent by dialysis facilities to their respective regional ESRD networks. The USRDS uses the blinded data from PMMIS/REBUS/REMIS for incidence and prevelance information, hospitalization and transplant rates, causes of death and cost. Some additional sources of data available to the CMS are claims data from procedures and inpatient facilities (Medicare part A) and outpatient providers (Medicare part B).
Information regarding ESRD patients collected from enrollment and claims data of participating EGHPs and certain private insurers may be non-standardized or incomplete. This small subset is usually included in incidence and prevelance counts, but not included for ratio calculations of mortality and transplants.
At the dialysis facility level, CMS obtains annual surveys from each dialysis facility for patient counts, new starts and death rates. No patient-level data are kept within this data set.
The initial source of transplant data for the USRDS was from CMS, which had collect data on Medicare kidney transplants since 1976. In 1986, UNOS was commissioned by the federal government to facilitate the allocation of all transplants and manage the associate data collection in a centralized fashion. UNOS established the OPTN/SRTR operations for the data collection process on all transplants performed in the United State since 1987. From 1987-1993, transplant data was collected by both CMS and UNOS and uploaded to SIMS, from which USRDS obtained the data. In 1994, the transplant data collection process was consolidated into UNOS and from that time on all transplant data for USRDS came exclusively from UNOS. The aggregated transplant data within USRDS consists of transplant waiting list information, transplant donor and recipient characteristics, as well as patient and kidney allograft events and outcome results. In 1999, UNOS developed an internet-based database access application called UNet, which allows transplant institutions to directly enter transplant information into the database.
The National Health and Nutrition Examination Survey (NHANES) program is an effort supported by the CDC which aims to collect health and nutritional information from a representative sample of the US population. NHANES accomplishes this by conducting surveys and physical examination of 5000 representative patients from 15 different counties through the US. Information is collected not only about patient demographics, but also various health conditions with anemia, cardiavascular disease, diabetes, kidney disease and obesity data being particularly relevant the renal community. NHANES was started in the early 1960’s as a series of surveys conducted for a few years followed by 1-2 year breaks. However, since 1999 the survey has become a continuous endeavor. The USRDS made available the relevant NHANES data for analysis starting with their 2006 data reports. The information extracted from NHANES was primarily for characterizing the pre-ESRD or CKD patient popluation, estimating incidence and prevelance rates along with examining relationships between kidney disease and various other health conditions.
The CDC also conducted annual dialysis facility surveys as part of their National Surveillance of Dialysis-Associated Disease program. The most recent set of surveys conducted from 1993-2002 was included in the USRDS. These surveys contained only facility data regarding dialysis associated diseases and practice patterns, no individual patient data is included. Dialysis-associated diseases include hepatitis, HIV, access infections and others, while dialysis-associated practices relates to types of machines and components used along with measures taken for disease control such as water treatment or vaccination histories.
USRDS DATA INTEGRITY:
The validity, completeness and reliability of the USRDS database have been examined by two Special Studies conducted by USRDS. In the Data Validation Special Study, samples of 1,692 ESRD patients were selected from the USRDS database and their information were validated by comparison to the original patient medical charts from the reporting facilities. Average concordance rate of 90.6% was found over 50 variables that were compared. Completeness and reliability of the USRDS data set was evaluated by identification of 12,730 Medicare ESRD patients from USRDS who lived in Michigan. The USRDS information for these patients was compared with available data from the Michagan Kidney Registry (MKR). After accounting for non-ESRD patients, only about 5% of the patients were unmatched, suggested a high level of completeness of the USRDS data set.
USRDS DATA UTILIZATION AND PRODUCTS:
The USRDS produces an Annual Data Report (ADR). The 2009 ADR, includes 2 atlases, one for CKD and the other for ESRD, as well as reference tables for ESRD. The ADR atlases contains graphical, tabular and textural narratives that present the findings of the various data elements; such as incidence and prevalence data, patient characteristics, disease trends, provider characteristic and practice patters, cardiovascular disease association, morbidity and mortality, transplantation, costs.
In 2001, USRDS developed an online data query application called Renal Data Extraction and Referenceing System (RenDER). This application is availabe through the USRDS website and allows researchers and other interested parties to develop custom data summary tables or maps from the USRDS database based on user submitted queries. Additionally, the patient level data used to create the ADRs are made available to researchers by means of Standard Analysis Files (SAF) stored on different CD sets. The patient identifying information stored on these CDs are either de-identified or encoded to conform to privacy guidelines. Custom data request can also be submitted to the USRDS if a researcher is unable to obtain the necessary information from either the ADR or the SAF CDs.
One of the stated goals of the USRDS is to support the development of special data collection studies that enhance the database that already exists. The most recent USRDS special study is the Comprehensive Dialysis Study (CDS), which is a prospective survey of 1646 incident dialysis patients through out the US, coordinated by the Qualtiy of life/Rehabilitation SSC. The survey questionnaire assessed health status, qualtify of life, satisfaction, function status, physical activity and employment status assessments. The information obtained was added to the overall USRDS database, thereby providing an additional dimension of qualitative assessment to complement the existing quantitative survival and outcomes data. Another extensive special study conducted by the USRDS was the Dialysis Mortality and Morbidity Study (DMMS), which was conducted in 4 waves spanning a time frame of nearly a decade and included 20,600 dialysis patients. These series of data collection waves obtained information on a number of dialysis treatment variables that have potential impact on morbidity and mortality such as dialyzer usage pattern, anemia treatment with erythropoietin, vascular access, medications and nutrition[9,10].
Submitted by John Hsieh
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 Jon J. Snyder, Robert N. Foley, Allan J. Collins. Prevalence of CKD in the United States: A Sensitivity Analysis Using the National Health and Nutrition Examination Survey (NHANES) 1999-2004. American Journal of Kidney Diseases - February 2009 (Vol. 53, Issue 2, Pages 218-228, DOI: 10.1053/j.ajkd.2008.07.034)
 Renquist J. Problems Pervade the Renal Beneficiary and Utilizatio System. Department of Health and Human Serivces: Office of Inspector General report. February 2002.
 Centers for Disease Control and Prevention. “About the National Nutrition and Health Examination Survey.” Available from http://www.cdc.gov/nchs/nhanes/about_nhanes.htm. July 21 2009. May 30 2010.
 Finelli L, et al. National Surveillance of Dialysis-Associated Diseases in the United States 2002. Seminars in Dialysis. Jaunary-Februray 2005:18(1), 52-61.
 USRDS, How good are the data? USRDS data validation special study. Am J Kidney Dis. 1992 Nov;20(5 Suppl 2):68-83.
 Completeness and reliability of USRDS data: comparisons with the Michigan Kidney Registry. Am J Kidney Dis. 1992 Nov;20(5 Suppl 2):84-8.
 Kutner NG, Johansen KL et al. The Comprehensive Dialysis Study (CDS): A USRDS Special Study. Clin J Am Soc Nephrol 4: 645-650, 2009. Doi: 10.2215/CJN.05721108
 U.S. Renal Data System, USRDS 1995 Annual Data Report: Atlas of Chronic Kidney Disease and End-Stage Renal Disease in the United States, National Institutes of Health, National Institute of Diabetes and Digestive and Kidney Diseases, Bethesda, MD, 1995. http://www.usrds.org/adr_1995.htm
 U.S. Renal Data System, USRDS 1999 Annual Data Report: Atlas of Chronic Kidney Disease and End-Stage Renal Disease in the United States, National Institutes of Health, National Institute of Diabetes and Digestive and Kidney Diseases, Bethesda, MD, 1999. http://www.usrds.org/adr_1999.htm