Providing Information for Health
Policy: National Health
Interview Survey (NHIS)
Eve Powell-Griner, PhD
National Center for Health Statistics
Centers for Disease Control and Prevention
National Center for Health Statistics
NHIS General Purposes
• Collect data on the health status of the US
population
• Address specific issues of current public
health concern
• Provide estimates for monitoring
(Health US, Healthy People)
NHIS Characteristics
• Household based
• Representative of U.S. and of four Census
regions (non-institutionalized civilian
population)
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Multi-stage, clustered design
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Computer-assisted personal interview (CAPI)
Data collected by U.S. Census Bureau
interviewers
NHIS Characteristics
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Proxy and self-report
Administered in English or Spanish
High response rates
Low item non-response
NHIS sample design
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2006 - 2013 design
 35,000 households
• 87,500 persons
• 28,000 sample adults
• 11,500 sample children
 Over-samples Black, Hispanic, and Asian
persons; adults 65 years of age or older
NHIS questionnaire modules
•
Basic module or core
 Fielded each year
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Supplemental modules
 New topics or more detail on core topics
 Different each year
NHIS Data Include
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•
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Health conditions
Health care access and utilization
Behavioral factors
Sociodemographic characteristics
NHIS Data and Policy
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Identify priority needs
Identify disparities
Identify health education needs
Track changes
Examples of NHIS Data Informing Policy
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Target appropriate populations for health
education and other interventions
 Obesity, hypertension
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Surveillance or monitoring
 Taking the longer view of lack of health
insurance coverage in the U.S.
 Vaccine availability and uptake
Percentage of adults aged 20 and older with
diagnosed hypertension, by race/ethnicity
1997
2007
40
Percentage
32.0
30
25.2
22.5
20
20.6
19.5
12.4
10
0
Non-Hispanic White
Non-Hispanic Black
Race/Ethnicity
SOURCE: CDC/NCHS, National Health Interview Survey
Hispanic
Prevalence of obesity among adults aged 20 years
and over: United States, 1997– September 2008
Percent
95% confidence interval
30
25
20
15
10
1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008
Jan.–Sept.
SOURCE: CDC/NCHS, National Health Interview Survey
Bars are 95% confidence intervals
Percentage of Adults Aged 18 and
Older Who are Obese
Non- Hispanic Black adults: 34.3%
Hispanic adults:
27.5%
Non-Hispanic White adults: 23.6%
Non-Hispanic Asian adults:
8.1%
Source: CDC/NCHS, National Health Interview Surve
SOURCE: CDC/NCHS, National Health Interview Survey
Percentage of Non-Hispanic Asian adults who are
obese, by Asian subgroup: 2004-2006
Chinese
Filipino
Asian Indian
Japanese
Vietnamese
20
14.1
Percentage
15
8.7
10
6.0
5
4.2
0
*Figure does not meet standards of reliability or precision.
SOURCE: CDC/NCHS, National Health Interview Survey
5.3
2.8 *
Korean
Percentage of adults aged 18 and older with diagnosed
hypertension, by obesity and race/ethnicity: 1997-2007
Obese
Not obese
Percent
40
20
0
NH White
NH Black
NH Asian
Hispanic
DATA SOURCE: CDC/NCHS: National Health Interview Survey, 1997-2007.
NH is Non-Hispanic. Non-Hispanic Asian refers to Non-Hispanic East Asian
Prevalence of diagnosed hypertension among adults aged 18 years
and older by BMI categories in four U.S. populations, 1997-2007
Adjusted for socio-demographics and health behaviors*
* Includes age, sex, education, poverty, marital status, insurance, residency, foreign-birth, health behaviors
SOURCE: CDC/NCHS, National Health Interview Survey, 1997-2007, Stommel and Schoenborn
Number and percentage of persons under 65
years of age without insurance: 1978 - 2007
50
43.3 million
Percentage
40
Number uninsured, in millions
30
20
16.6%
Percent uninsured
10
0
1978
1982
1986
1990
1994
1998
2002
2007
SOURCE: CDC/NCHS, National Health Interview Survey, health insurance supplements (prior to 1997) and family core questionnaire (starting
with 1997)
Percentage of near poor children with private coverage,
public coverage, and no coverage at the time of interview
Percent
60
Private coverage
50
40
30
20
Public coverage
Uninsured
10
0
1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008
(Jan – Sept)
Percentage of adults who had received an influenza vaccination
during the past 12 months, by quarter: 1997– September 2008
Percent
80
65 years and over
60
40
20
50–64 years
18–49 years
0
1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008
Year (quarter)
DATA SOURCE: Sample Adult Core component of the 1997–2008 NHIS. Data are based on household interviews of a
sample of the civilian noninstitutionalized population.
NHIS Strengths
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Large, representative sample
In-person survey
Broad range of information
Demographic detail
Ongoing annual survey
Topical supplementary information
Relatively high response rates
Links to other data sets
Timely release
NHIS Products
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Microdata files, questionnaires, related
products
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Reports
 Quarterly Early Release
 Annual summaries (U.S. population,
Adults, Children)
 Topical reports
 Data Briefs
 Health E-Stats
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Special web products
Where to find NHIS Products
http://www.cdc.gov/nchs/nhis.htm
NCHS Record Linkage Program
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Links survey data with data collected
from administrative records
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Designed to maximize the scientific
value of the NCHS population-based
surveys
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Examine factors that influence chronic
disease, disability, health care
utilization, morbidity, and mortality
Research Potential of NCHS Linked Data
• Aging
 Risk factors for poor health outcomes (hip fractures, stroke)
• Disability
 Effects of chronic illness and obesity on disability, mortality
• Disparities
 Mortality by race/ethnicity or socioeconomic status
• Health services
 Functional impairment and health care costs
• Methodologic Studies
 Validation of self-reports vs. administrative records
Record Linkage Activities
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Mortality
 National Death Index
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Social Security Retirement and
Disability
 Data from the Retirement, Survivors,
Disability Insurance (RSDI) and
Supplemental Security Income (SSI)
programs
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Medicare enrollment and claims data
NCHS Surveys with Linked Files
Mortality
(NDI)
NHIS 1986-2004
Medicare (CMS)
Retirement &
Disability (SSA)
X
X
X
NHIS 1994-2005
LSOA II
X
X
X
NHEFS
X
X
X
NHANES II
X
X
NHANES III
X
X
X
NHANES 1999-2004
X
X
X
NNHS 1985, 1995, 1997,
2004
X
NNHS 1997, 2004
X
X
Access to NCHS Linked Data Files
• All linked files accessible in the NCHS
Research Data Center
• Public-use linked mortality files contain
perturbed data to prevent disclosure risk
 1986-2000 NHIS, NHANES III, and LSOA II
available now
 Updated public-use files for mortality
linkages scheduled for release in early
2010
What is a Research Data Center
(RDC)?
• RDC provides a secure, controlled
environment where researchers can access
data files that cannot be released as Public
Use Files
• Confidentiality is protected because
researchers cannot link files to other data
sets that would allow subjects to be
identified
RDC Access Methods
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Four methods to access restricted data
 on-site at NCHS in Hyattsville MD
 remote – submit programs with output returned
by email
 staff assisted – RDC staff provide programming
for off-site researchers
 Census/RDC access
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Restricted data files remain in RDC and
output is inspected for disclosure
violations
For more information on
NCHS data linkage activities
http://www.cdc.gov/nchs/data_access
/data_linkage_activities.htm
Research Data Center
http://www.cdc.gov/nchs/r&d/rdc.htm