Data Sources

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• AASK (African American Study of Kidney Disease and Hypertension). The African American Study of Kidney Disease and Hypertension is a randomized, double-blind, controlled study in nondiabetic African Americans with hypertensive renal disease. Participants were assigned to received one of two levels of target blood pressure and also randomized to receive one of three antihypertensive drugs. The study aim was to determine the effects of blood pressure control level and specific antihypertensive dugs with the primary outcome of progression of hypertensive kidney disease as measured by change in GFR. The trial phase of the study was from 1995-2001 with a cohort follow-up phase from 2002-2007. Patients who provided written consent for DNA collection during the trial were genotyped for data including APOL1 marks.
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• ADD-CKD Cohort (ADD-CKD Cohort). The ADD-CKD cohort is comprised of 9,339 adults with type-2 diabetes mellitus (T2DM) from 466 different primary clinic sites across the United States. The study participants reflected a broad geographical distribution and had a variety of health insurance plans. On average, every site or provider involved in the study had 21 study participants. Participants had to be over 18 years old to qualify for the study, and must have had T2DM for one year or longer. Patients on dialysis or with a functioning transplant were excluded from the study. The ADD-CKD study is an observational study that assessed the prevalence of both undiagnosed and detected CKD in the cohort between 2011 and 2012. Investigators used a clinician survey, a patient physical exam, a blood draw for eGFR and HbA1c, a urine dipstick, urine albumin-creatinine ratio, two patient quality of life questionnaires, and a 15-month medical review to assess CKD prevalence.
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• AGRAWAL (Agrawal Survey). In the period of October to November 2007, Agrawal et al. (2009) conducted a national online survey of 479 internal medicine residents from 75 residency programs [166 post-graduate year 1 (PGY 1), 187 PGY 2 and 126 PGY 3 residents] identified via their fellowship program directors. The survey consisted of four clinical vignettes assessing nephrology referral patterns.
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• AMA (American Medical Association). AMA (American Medical Association) The American Medical Association (AMA) Physician Masterfile contains the most accurate and complete statistical data available about more than 972,000 U.S. physicians. The AMA obtains data from medical schools, hospitals, medical societies, the National Board of Medical Examiners, state licensing agencies and many others.
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• ARIC (Atherosclerosis Risk in Communities Study). ARIC (Atherosclerosis Risk in Communities Study) The Atherosclerosis Risk in Communities Study is a longitudinal study of 15,792 individuals ages 45-64 recruited from 4 U.S. suburban communities with a primary purpose of investigating the etiology and natural history of atherosclerosis, including the determination of risk factors. Baseline and follow-up visits (which occurred every 3 years) included measurements of demographics, lifestyle, physiologic characteristics, as well as laboratory measurements.
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• Atlanta Pediatric Clinics (Data from two pediatric practices in Atlanta and outpatient clinics at Children’s Healthcare of Atlanta). A cross-sectional cohort study comprised of children aged 8 to 18 years, living in the the metropolitan area of Atlanta. The control participants were recruited from two pediatric practices in Atlanta, while the participants with CKD were recruited from outpatient clinics and the hemodialysis unit at Children’s Health Care of Atlanta. The goal of the study was to compare the prevalence of restless leg syndrome between children with CKD and healthy controls. Participants in the CKD group had either a functioning transplant, were on dialysis, or had an eGFR less than 60 mL/min/1.73 m².   
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• BOULWARE (Boulware Survey). In the period August 2004-August 2005, Boulware et al. (citation: Boulware et al., 2006) conducted a national mail survey of 178 primary care providers (89 family physicians and 89 general internists; 28% response rate) and 126 nephrologists (39% response rate), identified with the American Medical Association Physician Masterfile. The questionnaire consisted of a hypothetical patient scenario, in which a primary care provider was evaluating a new patient with CKD stage 3 progressing to stage 4; the patient was identical for all cases (50-year-old female with creatinine values consistent with eGFR of 15-59 ml/min/1.73 m² and persistent proteinuria), except that her race/ethnicity (African-American or white) and comorbid illness status (hypertension only or hypertension with diabetes) varied by questionnaire. Physicians were asked to estimate the patient’s kidney function, and then were asked “How would you describe this patient’s kidney disease?” with possible responses of “normal or no kidney disease,” “mild kidney disease,” “moderate kidney disease,” “severe kidney disease,” and “end-stage kidney disease.” Responses of moderate or severe kidney disease were considered correct identification of CKD stage 3-4. Responding physicians were additionally asked: “Based on the information you know about this patient, do you recommend that the PCP refer the patient to a nephrologist at this time” with possible answers of “yes” or “no.”
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• CAP (College of American Pathologists). In June of 2003, 2005, and 2007-2010, CAP performed its General Chemistry B Survey, in which all College of American Pathologists (CAP)-accredited laboratories that performed routine chemistries (representing an estimated 80% or more of U.S. laboratories performing routine chemistries) were queried regarding their eGFR reporting practices. In the creatinine accuracy calibration survey, which is purchased by laboratories for self-assessment, CAP asked participants to state their creatinine calibration method: IDMS-traceable versus traditional calibration. Note that manufacturers were polled in June 2009; it was found that all major global manufacturers were currently distributing or planned by the end of 2009 to only distribute IDMS-traceable serum creatinine methods in all markets they serve.
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• CKiD (Chronic Kidney Disease in Children). Chronic Kidney Disease in Children (CKiD) Study is a prospective observational cohort study of 594 children (1-16 years old) with mild to moderate CKD (Schwartz-estimated GFR of 30-90 ml/min/1.73 m²) who are treated at 48 pediatric nephrology centers throughout North America (46 in the United States; 2 in Canada). Enrolled patients are approximately 60% male, 70% white, 16% African-American, and 16% obese. On average, enrolled patients have had CKD for 6-7 years and 22% have a glomerular diagnosis. As with all cohort studies, selection bias may affect study results, as those who participate in such a study may differ from the overall pediatric CKD population in important and possibly unmeasurable ways (e.g., very sick patients may be excluded if they cannot complete a baseline visit).
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• Clinformatics Commercial (Clinformatics Commercial). The Optum Clinformatics™ Data Mart provides paid medical and prescription claims and enrollment information for participants in commercial insurance plans and Medicare Advantage plans of a large U.S. managed care health insurance company. The data are purchased from OptumInsight, and included plan members are enrolled in both a medical and a prescription plan. All areas of the country are represented in the data. 
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• Clinformatics Medicare Advantage (Clinformatics Medicare Advantage). The Optum Clinformatics™ Data Mart provides paid medical and prescription claims and enrollment information for participants in commercial insurance plans and Medicare Advantage plans of a large U.S. managed care health insurance company. The data are purchased from OptumInsight, and included plan members are enrolled in both a medical and a prescription plan. All areas of the country are represented in the data. 
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• Clinical Trials (Meta-analysis based on one cohort study and five clinical trials).
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• CMS-ESRD (Centers for Medicare & Medicaid Services - ESRD Population). The Centers for Medicare & Medicaid Services (CMS) has substantial data on U.S. residents over the age of 65, the disabled, and those with end-stage renal disease, which is covered by CMS regardless of age.
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• CMS-Medicaid (CMS-Medicaid (Centers for Medicare & Medicaid Services-Medicaid) for Michigan). The Centers for Medicare & Medicaid Services (CMS) has substantial data on US residents with low incomes and limited resources that include low-income adults, children, pregnant women, older adults, and people with disabilities. Medicaid is funded jointly by states and the federal government. This program is administered by states, so the exact rules of Medicaid eligibility vary across states. The data arrives in separate files for each state. Data for additional states will be added when available.
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• CMS-Medicare (Centers for Medicare & Medicaid Services - Medicare). The Centers for Medicare & Medicaid Services (CMS) has substantial data on U.S. residents over the age of 65, the disabled, and those with end-stage renal disease, which is covered by CMS regardless of age.
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• CRIC (Chronic Renal Insufficiency Cohort Study). CRIC (Chronic Renal Insufficiency Cohort Study) The Chronic Renal Insufficiency Cohort (CRIC) Study is an observational cohort study of >3,000 individuals at 13 sites across the United States with chronic renal insufficiency, which was established to study the consequences of CKD with a particular focus on cardiovascular illnesses like myocardial infarction (heart attack) and stroke. No study treatments or interventions were given to participants in CRIC. Subjects were followed for 5 years and included a racially and ethnically diverse group of adults aged 21 to 74 yrs with a broad spectrum of renal disease severity, half of whom have diagnosed diabetes mellitus. As with all cohort studies, selection bias may affect study results, as those who participate in such a study may differ from the overall CKD population in important and possibly unmeasurable ways (e.g., very sick patients may be excluded if they cannot complete a baseline visit).
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• CRISP (The Consortium for Radiologic Imaging Studies of Polycystic Kidney Disease). CRISP (The Consortium for Radiologic Imaging Studies of Polycystic Kidney Disease) is a 10-year prospective cohort study that started in March 1999 and was created to develop innovative imaging techniques and analyses using magnetic resonance (MR) imaging to reliably and accurately measure cyst and renal volume in autosomal dominant polycystic kidney disease (ADPKD) individuals early in the course of their disease.
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• D-ARIC and JHS (Dental-Atherosclerosis Risk in Communities Study and the Jackson Heart Study). A cohort of African American participants enrolled in the Dental-Atherosclerosis Risk in Communities study (D-ARIC), were subsequently enrolled in the Jackson Heart Study (JHS). The Atherosclerosis Risk in Communities Study is a longitudinal study of 15,792 individuals ages 45-64 recruited from 4 U.S. suburban communities with a primary purpose of investigating the etiology and natural history of atherosclerosis, including the determination of risk factors. The D-ARIC study, which was conducted between 1996 and 1998, involved a subgroup of the ARIC cohort visit 4. Partcipants underwent an oral examination by dental hygenists. The clinical measures examined were bleeding on probing, probing depth, and gingival recession.The Jackson Heart Study is a community-based cohort study with the primary focus of examining risk factors for cardiovascular disease among African Americans. The study was conducted between 2000 and 2004. All participants were living in the tri-county area of Jackson, Mississippi. The final cohort of individuals enrolled in both the D-ARIC and JHS studies was comprised of 669 individuals. There were 240 males, 459 females, and the average age was 65. 
   
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• DoD-MHS (Department of Defense Military Health System).

  The US Department of Defense (DoD) Military Health System (MHS) is one of America’s largest health care institutions, providing comprehensive primary and specialty care for more than 9.6 million active duty personnel, military retirees, and their families worldwide. The MHS Data Repository (MDR) is the administrative claims database for all care received through the MHS, including direct care received in military treatment facilities and purchased care received in the civilian network. The MDR does not capture health care delivery in combat zones or care received in the Veterans Affairs (VA) system. All patients were in the TRICARE Prime managed care option.
  
  The views expressed are those of the authors and do not reflect the official policy of the Uniformed Services University, Departments of Army/Navy/Air Force, Department of Defense, Centers for Disease Control and Prevention, Department of Health and Human Services, or the US Government.

  
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• Framingham (Framingham Offspring Study). The Framingham Offspring Study (FOS) is a longitudinal cohort of the offspring of the original Framingham Heart Study, which comprised a cohort of primarily white men and women from Framingham, MA and was designed to study causes of cardiovascular disease. The FOS cohort, which began in 1971, contains 5,124 participants. Follow-up examinations of this cohort occur every 4 years.
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• Jackson Heart Study (Jackson Heart Study). The Jackson Heart Study is a longitudinal cohort study of noninstitutionalized African Americans aged 21 years and older from three Jackson, Mississippi Metropolitan Statistical Area counties, Hinds, Madison, and Rankin. A total of 5,301 participants were examined at baseline. The primary objective of the study is to monitor the cause and progression of cardiovascular disease in African Americans from Jackson, MS. Baseline data, which was collected between September 2000 and March 2004, were collected from a home visit, self-administered questionnaires, and a clinic visit. At the clinic visit, medication use was ascertained, fasting blood and urine samples were obtained, and blood pressure readings were taken. 
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• KPNC (Kaiser Permanente Northern California). The source population was Kaiser Permanente Northern California, a large integrated health care delivery system that provides comprehensive inpatient and outpatient care for >3.2 million members in the San Francisco and greater Bay Area. The Kaiser Permanente Northern California population is highly representative of the local surrounding and statewide population with regards, to age, gender, race/ethnicity and comorbidity burden, with only slightly lower representation at the extremes of age and income.  The study samples included all Kaiser Permanente Northern California adult members aged 40 years or older as of January 1^st of each calendar year of interest and who had known eGFR of 150 ml/min/1.73 m² or less based on ambulatory, non-emergency department serum creatinine measures found in health plan databases. Estimated GFR was calculated using the CKD-EPI equation. Given the focus on CKD prior to ESRD, all patients with prior chronic dialysis or receipt of renal transplant were excluded. 
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• NATIONAL VA (Veterans Affairs Health System). NATIONAL VA (Veterans Affairs Health System) The Department of Veterans Affairs (VA), through the Veterans Health Administration (VHA), operates the largest integrated health care system in the United States. The MedSAS Inpatient and Outpatient data sets and the Decision Support System (DSS) National Data Extracts for laboratory results (LAR) and pharmacy records (PHA) and vital status data from the Beneficiary Identification Records Locator Subsystem (BIRLS) were used for the Surveillance System. More information on these data sets can be retrieved at: http://www.virec.research.va.gov/
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• NHANES (National Health and Nutrition Examination Survey). NHANES is arguably the largest and longest-running national source of objectively measured health and nutrition data. Through physical examinations, clinical and laboratory tests, and personal interviews, NHANES provides a "snapshot" of the health and nutritional status of the U.S. population. Findings from NHANES provide health professionals and policymakers with the statistical data needed to determine rates of major diseases and health conditions (e.g., cardiovascular disease, diabetes, obesity, infectious diseases) as well as identify and monitor trends in medical conditions, risk factors, and emerging public health issues, so that the appropriate public health policies and prevention interventions can be developed.
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• NHANES and the CKD HPM (National Health and Nutrition Examination Survey and the CKD Health Policy Model). The CKD Health Policy Model is a microsimulation model for CKD progression that simulates the history of CKD for adults aged 30 to 90 years old. All adults used in the model had been participants in the National Health and Nutrition Examination Survey (NHANES) from 1999 through 2010. The model placed participants into one of seven different categories: no CKD, Stages 1-5, and death. CKD stage was determined by eGFR and the presence of albuminuria using the NKF-KDOQI guidelines. The model was used to project the prevalence and lifetime incidence of CKD through the year 2030. NHANES is arguably the largest and longest-running national source of objectively measured health and nutrition data. Through physical examinations, clinical and laboratory tests, and personal interviews, NHANES provides a "snapshot" of the health and nutritional status of the U.S. population. Findings from NHANES provide health professionals and policymakers with the statistical data needed to determine rates of major diseases and health conditions (e.g., cardiovascular disease, diabetes, obesity, infectious diseases) as well as identify and monitor trends in medical conditions, risk factors, and emerging public health issues, so that the appropriate public health policies and prevention interventions can be developed.
   
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• NHANES III (National Health and Nutrition Examination Survey III). The National Health and Nutrition Examination Survey III (NHANES III) is an earlier version of today’s continuous NHANES; this third iteration of the National Health Examination Survey was conducted from 1988-1994. NHANES III focused on oversampling many groups within the U.S. population aged 2 months and over. These oversampled groups included children aged 2 months to 5 years, persons over age 60, Mexican-American persons, and non-Hispanic black persons. This survey also concentrated on health and nutrition but additionally began to collect environmental exposure and infectious disease data. More information on this data set can be found at: http://www.cdc.gov/nchs/nhanes/nh3data.htm
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• NHANES-CMS (National Health and Nutrition Examination Survey-CMS). NHANES is arguably the largest and longest-running national source of objectively measured health and nutrition data. Through physical examinations, clinical and laboratory tests, and personal interviews, NHANES provides a "snapshot" of the health and nutritional status of the U.S. population. Findings from NHANES provide health professionals and policymakers with the statistical data needed to determine rates of major diseases and health conditions (e.g., cardiovascular disease, diabetes, obesity, infectious diseases) as well as identify and monitor trends in medical conditions, risk factors, and emerging public health issues, so that the appropriate public health policies and prevention interventions can be developed. There are 3 potential sources for CMS data related to CKD: (i) ResDac: The Research Data Assistance Center (ResDAC) is a CMS contractor (in Minnesota) that provides free assistance to academic, government and non-profit researchers interested in using Medicare and/or Medicaid data for their research. (ii) directly from the CMS, and (iii) from the USRDS (Annual reports from the USRDS include a section on CKD). We are investigating as to which will be the most cost-effective source for CMS data for the CKD Surveillance Project. A wide variety of data files would potentially be required and will require significant programmatic/analytic expertise and effort.
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• NHANES-NDI (National Health and Nutrition Examination Survey-NDI). NHANES is arguably the largest and longest-running national source of objectively measured health and nutrition data. Through physical examinations, clinical and laboratory tests, and personal interviews, NHANES provides a "snapshot" of the health and nutritional status of the U.S. population. Findings from NHANES provide health professionals and policymakers with the statistical data needed to determine rates of major diseases and health conditions (e.g., cardiovascular disease, diabetes, obesity, infectious diseases) as well as identify and monitor trends in medical conditions, risk factors, and emerging public health issues, so that the appropriate public health policies and prevention interventions can be developed. The National Death Index (NDI) is a central computerized index of death record information on file in the State vital statistics offices. Working with these State offices, NCHS established the NDI as a resource to aid epidemiologists and other health and medical investigators with their mortality ascertainment activities.
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• NiCK Study (Neurocognitive Assessment and Magnetic Resonance Imaging Analysis of Children and Young Adults with Chronic Kidney Disease (NiCK) Study). The Neurocognitive Assessment and Magnetic Resonance Imaging Analysis of Children and Young Adults with Chronic Kidney Disease (NiCK) study is a cross-sectional cohort study involving children and young adults, aged 8 to 25 years. The study compares the neurological function of those with CKD to those without CKD, with the goal of identifying any neurologial abnormalities in the CKD population. The study assessment involves neurocognitive testing, clinical phenotyping, multimodal magnetic resonance imaging (MRI) of the brain, functional connectivity, and blood flow. Participants were included in the CKD group if they had 2 estimated glomerular filtration rates (eGRFs) less than 90 mL/min/1.73 m² over at least 6 months. Participants could qualify for the CKD group regardless of whether they had received a transplant or were on dialysis. All study particpants spoke English as their primary language. Control participants were recruited from pediatric practices in the the Children's Hospital of Philadelphia network.
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• NIS (Nationwide Inpatient Sample). The Nationwide Inpatient Sample (NIS) is a U.S. nationally representative administrative database of hospitalizations. The NIS is the largest all-payer publicly available national hospital database containing a 20% stratified sample of all short-term, nonfederal, nonrehabilitation hospitals. Hospitals are sampled according to geographic region, location (urban/rural), teaching status, ownership, and bedside; all discharges from sampled hospitalizations are included in the database. The NIS was developed as a part of the Health Care Cost and Utilization Project (HCUP), sponsored by the Agency for Health Care Research and Quality (AHRQ).
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• NKDEP (National Kidney Disease Education Program). NKDEP (National Kidney Disease Education Program) is an initiative of the National Institutes of Health, designed to reduce the morbidity and mortality caused by kidney disease and its complications. NKDEP aims are: improving early detection of CKD facilitating identification of patients at greatest risk for progression to kidney failure; promoting evidence-based interventions to slow progression of kidney disease; and improving the coordination of Federal responses to CKD to raise awareness of the seriousness of kidney disease, the importance of testing those at high risk (those with diabetes, high blood pressure, or a family history of kidney failure), and the availability of treatment to prevent or slow kidney failure. NKDEP's Coordinating Panel includes representatives of voluntary and professional organizations that are actively engaged in kidney disease activities. NKDEP's reports include findings from focus groups, literature reviews, its strategic plan, and baseline report from its Strategic Development and Planning Meeting.1-“African-Americans Unaware of High Kidney Disease Risk”, released March 8, 2004. 2-The NKDEP’s eGFR Laboratory Implementation study.
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• Norwegian Tromso Study (Norwegian Tromso Study ). The Tromsø Study is a population-based, longitudinal study with repeated health surveys of inhabitants in the municipality of Tromsø, Norway. Originally a cardiovascular study, it now focuses on several chronic and lifestyle-related conditions such as atherosclerosis and diabetes.
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• Renal REGARDS (Renal Reasons for Geographic and Racial Differences in Stroke). Renal REGARDS represents a subcohort of 12,030 participants from the Reasons for Geographical and Racial Difference in Stroke (REGARDS) cohort study. Participants are a population-based sample of adults, 45 years and older, from the United States who were recruited in 2003-2005. All eligible participants were tested for kidney function.
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• SEARCH (SEARCH for Diabetes in Youth Study). The SEARCH for Diabetes in Youth Study (SEARCH for Diabetes in Youth Study) (Study Group, 2004) aimed to estimate population prevalence and incidence of diabetes in youth (children and adolescents aged 0-19) according to age, gender, race/ethnicity, and type of diabetes. SEARCH collected data from 6 centers in California (Kaiser Permanente of Southern California, excluding San Diego), Hawaii (Hawaii Medical Service Association, Med-Quest, and Kaiser Permanente Hawaii), Colorado (13 counties, including reservation-based American Indian populations), Ohio (8 counties including Cincinnati), Washington (5 counties including Seattle), and South Carolina. Active surveillance through endocrinologists, existing databases, health plan databases, and health providers was conducted in the latter 4 centers to identify cases of diabetes in 0- to 19-year-olds. Cases were validated by physician report, medical record review, or self-report of physician. Denominators for civilian youth populations were calculated by removing children of active-duty military personnel, and weighting for race/ethnicity and gender was performed to approximate the U.S. census population of youth.
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• SHS (Strong Heart Study). The Strong Heart Study is a prospective, observational cohort designed to measure cardiovascular disease and its risk factors among American Indian men and women.
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• SRTR (Scientific Registry of Transplant Recipients). The Scientific Registry of Transplant Recipients (SRTR) supports the ongoing evaluation of the scientific and clinical status of all solid organ transplantation in the United States, including kidney transplants.
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• U.S. Census (United States Census). The United States Census is a Congress-mandated effort performed every 10 years to establish the geographic distributions of U.S. residents. In 2000, information on age, race/ethnicity, and gender was collected from 115.9 million housing units and 281.4 million people across the United States.
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• USRDS (United States Renal Data System). The USRDS is an NIDDK and CMS-sponsored national database, predominantly for end-stage renal disease. It provides national statistics on ESRD incidence and prevalence, treatment modalities, achievement of clinical indicators, and clinical outcomes. The USRDS annual data report has a section on CKD based on the 5% Medicare sample and employee group health plans (predominantly based on data from the privately owned data warehouse Medstat). CKD diagnosis is by ICD-9 Codes. Laboratory Data are available in a small fraction of the Medstat data bases. Pharmacy claims data are available from the Medstat source for CKD.
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