National Health Interview Survey (NHIS)

1. National Health Interview Survey (NHIS) “The principal source of information on the health of the U.S. population”

2. Overview • Initiated in 1957 by the National Center for Health Statistics • NHIS data are collected through personal household interviews • Purpose: provide data to track • Health status • Health care access • Progress towards achieving national health objectives

3. Survey sample • Large-scale household interview survey of a statistically representative sample of U.S. civilian, non-institutionalized population • Interviewers visit 35,000-40,000 households across the country and collect data on 75,000 to 100,000 individuals

4. Sample Design • Multistage area probability design • State-level stratification to allow use of the NHIS for producing state estimates (for larger states only) • State identifiers not released  Research Data Centers • Oversampling of black, Hispanic, and Asian populations • Sample adult selection process has been revised so that when black, Hispanic, or Asian persons age ≥ 65 years are present, they have an increased chance of being selected as the sample adult.

5. NHIS Basic Module, or Core Sample Child Core Family Core • RANDOM SELECTION: • One sample child (< 18) • One sample adult Collects information on everyone in the family Sample Adult Core • Household composition • Sociodemographic characteristics • Basic indicators of health status • Activity limitations • Injuries • Health insurance coverage • Access to and use of health care servives

6. Data collection procedures • For the Family Core: • All members of the household age ≥ 18 years and who are at home at the time of the interview are invited to participate and to respond for themselves. • For children and those adults not at home during the interview, information is provided by a knowledgeable adult family member age ≥ 18 years residing in the household.

7. Data collection procedures, cont’d • For the Sample Child questionnaire: • Obtained from a knowledgeable adult residing in the household. • For the Sample Adult questionnaire: • One adult per family is randomly selected • This individual responds for him/herself to the questions in that section • Unless s/he is physically or mentally unable to do so  knowledgeable PROXY is allowed to answer for the sample adult (~350 cases per year)

8. Response rates • Response rates: • For the Family Component: 78.7% • Conditional (number of completed interviews divided by the number of eligible sample children/adults) • For the Sample Child Component: 89.8% • For the Sample Adult Component: 77.3% • FINAL RESPONSE RATE: 60.8%

9. Weighting information • The sample is chosen in such a way that each person in the covered population has a known non-zero probability of selection. • These probabilities of selection, along with various adjustments (e.g., for non-response), are reflected in the sample weights that are provided in the data files.

10. Survey content • A core set of questions that remain almost unchanged from year to year • Supplemental questions that change from year to year that collect additional data on about current issues of national importance. • Examples of supplements include: cancer screening, family history of cancer diet and nutrition, physical activity, tobacco use, sun protection. • Nearly 20 minutes of an average NHIS interview is devoted to supplemental questions.

11. What are NHIS data used for • Identify health problems • Determine barriers to accessing care • Evaluate health problems • Study health-related disparities • Monitor progress toward national health objectives • Monitor progress toward national well-being indicators.

12. The Health and Retirement Study (HRS)

13. Overview • The HRS is the largest ongoing prospective longitudinal study of older persons’ health in the U.S. • Beginning in 1992, a nationally representative sample of more than 30,000 persons over 50 years of age and their spouses has been interviewed every two years through 2008.

14. Overview, cont’d • At each interview, self- or proxy-reported data are collected on a number of domains. • The HRS employs a complex multistage area probability sampling design, with oversampling of households with a Black or Hispanic head.

15. Introduction » Data Collection Path Source: http://hrsonline.isr.umich.edu/sitedocs/surveydesign.pdf

16. Contents • Demographics, income, education • Self-reported comorbid conditions • Heart disease • Lung disease • Hypertension • Cancer • Diabetes • Arthritis • Stroke • Psychiatric Conditions

17. Contents, cont’d • Self-reported health status and decline • Functional status • Cognitive status • Depressive symptoms • A number of conditions that can be grouped under the rubric of geriatric syndromes • Urinary incontinence, fall, visual/hearing impairment

18. Contents, cont’d • Height and weight  BMI • Smoking • Alcohol consumption • Physical activity • Perceived life expectancy

19. Contents, cont’d • Hospitalizations • Nursing home admission • Use of preventive services (cancer screening)

20. The RAND files • Streamlined, processed files that combines data from all the waves to create a unique record for each respondent and their spouse • More user-friendly than the raw HRS files • However, not all the data elements are available in the RAND files.

21. Use of HRS data • Numerous ways by which to characterize the older U.S. population • Multimorbidity in relation to: • Socio-demographics • Health status, decline, mortality • Use of preventive services • Frailty, using various definitions (Cigolle et al.) • Health status/decline by cancer survivor status • …..

22. Important analytic considerations • Weighted data • Consider representativeness of the study cohort (people who have agreed to participate in the study every 2 years) • Mortal vs. non-mortal attrition

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