Dataset Summary
Overview
NHATS is a nationally-representative longitudinal panel survey of approximately 9000 Medicare beneficiaries age 65 and older who are followed every year. It started in 2011, and the panel was replenished with new subjects in 2015.
Who is in the data, and how are they followed?
NHATS includes a nationally representative sample of Medicare beneficiaries age 65 and older identified from the Medicare enrollment file. At the time of enrollment, eligible participants included people living at home and in various types of residential care facilities, including assisted living facilities and nursing homes. Following their enrollment interview, subjects receive in-person followup interviews every year thereafter, regardless of place of residence. For example, if a subject moved from a residential care facility in wave 1 to a nursing home in wave 2, he/she has subsequent annual interviews done in the nursing home. People who were in the nursing home at the time of enrollment have more limited data collection, with questionnaires administered only to a facility staff member at the time of enrollment and in subsequent waves. Black/non-Hispanic older adults and the old-old are oversampled, allowing greater statistical power for studies focused on these populations. Patient weights and other survey design factors are provided in the data so that results can be adjusted to be nationally representative.
The first group of participants enrolled in 2011. A second group was enrolled in 2015. Proxy respondents are used when subjects cannot respond for themselves.
The National Study of Caregiving (NSOC) is a supplemental study concurrent with the 2011 and 2015 Rounds of NHATS. This study used telephone interviews to collect data about informal caregiving by family and non-paid helpers of NHATS participants who were receiving help with household activities, self-care, or mobility.
What kind of information is in the data?
NHATS collects information on a wide range of domains pertinent to older adults, including cognitive and physical capacity (both by self-report and objective testing), functional performance and activities of daily living, participation in valued activities, physical, social, and technological environments, living arrangements, economic status, and more. NHATS is unique in its detailed assessment of functioning with detailed questioning on how subjects conduct each activity and adapt to increasing difficulty. In addition, a last month of life interview is conducted among descendents to collect information on place and quality of end-of-life care, and on daily activities since the last interview. Many of the measures used have been validated (see user guide).
For patients living in residential care or nursing home facilities, a facility questionnaire is also completed based on responses of a staff person at the facility. As noted above, subjects receiving long-term care in a nursing home at the time of initial enrollment did not have interviews conducted, although a facility questionnaire was completed for these subjects.
The National Study of Caregiving contains information about the frequency, volume, and types of informal caregiving provided to older adults, and how caregiving affects the life, wellbeing, health, and economic status of caregivers.
Technical guidance about the origin and validity of measures in NHATS can be found in the user guide, technical papers, publications, and via the NHATS help desk.
Practical issues with acquiring and using NHATS data:
The main NHATS datasets are de-identified. SAS and STATA data files are available to download free of charge after registering through the NHATS website. Because the data are de-identified, many IRBs will provide an exemption from review.
Several types of additional data are available for linkage with NHATS data. These include:
- Data from the National Study of Caregiving (NSOC), described above
- “Sensitive” information about NHATS subjects and their family members, including expanded demographic data
- Geographic data about NHATS participants
- Linked Medicare beneficiary and claims data
Sensitive data and National Study of Caregiving data can be obtained after a review process conducted by the NHATS Data Confidentiality Committee. Geographic identifiers and linked Medicare data require an additional level of scrutiny, including application to the Centers for Medicare and Medicaid Services (CMS) for approval to use their data. Linked Medicare inpatient and outpatient claims data cost roughly $1000 per year of data, with higher fees for other types of data such as Medicare Part D (pharmacy) data.
NHATs data are organized in modules. The questions are well-documented but require close attention due to skip patterns in the data and question inputs that can be complex. NHATS provides survey weights and design features that can be incorporated into analyses to generate nationally representative adults. Not incorporating these features into analyses may lead to misleading results.
Data are available for researchers approximately 2 years after they are collected. Obtaining the basic deidentified NHATS data file is quick, requiring only registration on the NHATS website. Obtaining linked data, for example NHATS-Medicare data, typically takes months.
Overall, NHATS is still fairly young but is emerging as a valuable source of nationally representative data on older adults. While it takes substantial effort and time to learn the dataset and manage the many types of data available, NHATS data are relatively easy to obtain, easy to use, and well-documented, making them amenable for new users with a moderate amount of effort.
Areas of Particular Interest for Research on Function and Disability in Vulnerable Populations
NHATS is a valuable resource for research on function and disability in older adults and the multiple ways these phenomena can affect the lives of older adults and those around them. Annual follow-up interviews that follow the patient regardless of residence (i.e. staying in the community or moving to a residential care facility) provide an excellent means to evaluate trajectories of health, functioning, and other life parameters among older adults.
Measures from NHATS of particular interest include:
- Physical performance measures such as simple strength, gait, and balance parameters, and cognitive performance measures
- Extensive information on physical functioning, disability, and related domains, and how they restrict participation in valued activities.
- Home environment and compensatory strategies to manage functional limitations
- Self-reported chronic conditions, self-care activities, and medical care activities
- Economic parameters, labor history, and social connections
- Extensive information on informal caregiving via the National Study of Caregiving