Understanding the High Prevalence of Low-Prevalence Chronic Disease Combinations: Databases and Methods for Research. National Institute on Aging Dataset


National Health & Aging Trends Study
Database Description
White Paper(s): Data Systems and the Prevalence of Chronic Disease Combinations & Multiple Chronic Conditions and Disparities.
Sponsorship: National Institute on Aging

The National Health and Aging Trends Study (NHATS) is a new resource for the scientific study of functioning in later life.The NHATS is being conducted by the Johns Hopkins University Bloomberg School of Public Health, with data collection by Westat, and support from the National Institute on Aging. In design and content, NHATS is intended to foster research that will guide efforts to reduce disability, maximize health and independent functioning, and enhance quality of life at older ages.

The NHATS will gather information on a nationally representative sample of Medicare beneficiaries ages 65 and older. In-person interviews will be used to collect detailed information on activities of daily life, living arrangements, economic status and well-being, aspects of early life, and quality of life. Among the specific content areas included are: the general and technological environment of the home, health conditions, work status and participation in valued activities, mobility and use of assistive devices, cognitive functioning, and help provided with daily activities (self-care, household, and medical). Study participants will be re-interviewed every year in order to compile a record of change over time. The content and questions included in NHATS were developed by a multidisciplinary team of researchers from the fields of demography, geriatric medicine, epidemiology, health services research, economics, and gerontology.

As the population ages, NHATS will provide the basis for understanding trends in late-life functioning, how these differ for various population subgroups, and the economic and social consequences of aging and disability for individuals, families, and society.

Database: (Scope, Size, Setting, Population, Age Range) National; persons >=65 years old; Adolescents Only (< 20 years old); 2–3 million records a year.
Database Type: (Survey, Registry, Research Study, Program Database, Claims, Administrative Data, and Clinical Databases) Survey
Database Source/Origin: Sample of Medicare beneficiaries
Date or Frequency of Data Collection: Annual (round 1 completed in 2011)
Longitudinal vs. Cross-sectional Database: Longitudinal
Data Collection Methodology: Interview
Sampling Strategy: Sample of over 8,000 Medicare beneficiaries ages 65 and older living in the contiguous U.S. Age-stratified so that persons are selected from 5 year age groups between the ages of 65 and 90, and from among persons age 90 and older. Oversample of persons at older age groups and persons whose race is listed as Black on the CMS enrollment file. Replenishment of the sample to maintain the ability to represent the older Medicare population is planned at regular intervals.
Unit of Analysis: Patient
Diagnosis Information
Diagnosis Variable Type: (Chronic Condition Status, Principal Diagnosis, Primary Diagnosis, Secondary Diagnosis, Admit/Discharge Diagnosis and Self-Reported Diagnosis) Number of Chronic Conditions (based on a list of 25 possible chronic condition indicators) Primary and Secondary Diagnoses Admission and Discharge Status
Diagnosis Codes: (ICD-9, ICD-10, SNOMED) None (self-report by patient)
Number of Diagnoses Captured: 10 basic diagnoses (heart attack, heart disease, high blood pressure, arthritis, osteoporosis, diabetes, lung disease, stroke, dementia, cancer); more detailed questions are asked about each one if interviewee reports having or having had one or more of these illnesses. Additional questionnaires ask about cognitive status, mobility, sensory and physical impairments, and ACS disability questions
Cost, Utilization & Clinical Information
Measures of Cost: (Claims, Out-of-pocket expenses, Self- reported expenditures, and Prescription Drug Costs) Out-of-pocket cost of home environment modifications
Measures of Healthcare Utilization: (Number of Visits, Any Procedures/Number of Procedures/Type of Procedure, Number of Admission/Type of Admission, Length of Stay, Hospitalizations, Emergency Department Utilization, etc.) Hospital stays/surgery, use of a medical doctor
Measures of Healthcare Access: Measures of ability to handle medical care activities by oneself, whether patient has a regular doctor
Demographic Information: (Sex, Age, Race, Ethnicity, Marital Status, Disability Status, Language, Insurance Type, Educational Attainment). Sex, Age, Race, Ethnicity, Marital Status, Disability Status, Language, insurance, education
Clinical Information: (BMI, Medical Conditions [high blood pressure], Smoker Status, History of Various Conditions, Preventative Health Measures , Activities of Daily Living, Instrumental Activities of Daily Living) Various indicators of physical, social, sensory and cognitive functioning
Measures of Socioeconomic Status: (Occupation, Employment Status, Income, Wealth, Place of Residence, Household Size & Composition, geographic location) Income, assets, housing, car ownership, labor force participation, helpers
Site of Service Information:  
Measures of Healthcare Outcomes: (Mortality, Morbidity, Mobility, Functional Status, Quality of Life, Quality Measures, Quality of Care, Readmissions) Mortality (year to year), mobility, ability to complete activities of daily living, functional status
Strengths, Limitations & Feasibility
Data Strengths: Survey, longitudinal
Data Limitations: Small sample size (8,000), little information about rarer conditions
Data Access Restrictions: Users must register before downloading the data. Registration is instant and free online.
Data Linking Feasibility: (Unique identifiers or sufficient demographics to allow for data linkages) Does not appear to be linkable to Medicare file.
Related Grouping Systems: N/A


Full bibliography available at http://www.nhats.org/scripts/biblioRep.htm


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