Using the Sampling Frame for Major National Health Surveys for Other HealthRelated Surveys

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Using the Sampling Frame for Major National
Health Surveys for Other Health-Related Surveys
Trena M. Ezzati-Rice National Center for
Health Statistics Centers for Disease Control
and Prevention
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Overview of data collection methods

• Vital statistics data collected in partnership
  with states
• Household interview surveys
• Examination surveys
• Health care provider surveys

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Four major data systems

• National Vital Statistics System and surveys
• National Health Interview Survey
• National Health and Nutrition Examination Survey
• National Health Care Survey

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NCHS data are used for

• Comparisons across populations, providers, and
  geographic areas
• Planning/assessing public health programs
• Identifying health problems, risk factors, and
  disease patterns

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Outline

• Overview of U.S. Dept. of Health and Human
  Services (DHHS) Survey Integration Plan
• Overview of the National Health Interview Survey
  (NHIS) sample design
• Overview of surveys targeted for linkage to the
  NHIS

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Outline

• Goals and objectives of the surveys targeted for
  linkage
• Summary of sample design and how linked to the
  NHIS (current or in past)
• Summary of advantages and limitations of linkage
• Other strategies for linkage
• Methodological research issues for integration of
  health surveys
• Summary

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Impetus for Survey Integration

• DHHS - number of population-based surveys
• Operation of surveys decentralized
• Perceived overlap and duplication
• Operational inefficiencies
• Major gaps in data or health care costs
  expenditures - on an annual basis

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Impetus for Survey Integration

• Inability to analytically link data from
  different sources
• Reduce costs
• Emerging health data needs at the State level

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Key Elements of DHHS Survey Integration Plan

• Use of common sampling frames - NHIS as sampling
  nucleus
• Use common core questionnaires and common
  definitions and terms
• Reduce overlap
• Increase analytic capabilities
• Ease of use for research analysts
• Consolidate field operations for surveys of
  employers and health care providers

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Key Elements of DHHS Survey Integration Plan

• Sharing knowledge and resources to reduce costs
• instrument testing
• sample design techniques
• estimation techniques
• Implement an ongoing longitudinal panel survey
• Redesigning NHANES using NHIS as its sampling
  frame
• Develop capacity for State-level estimates

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Household Surveys Targeted for Linkage to NHIS

• National Survey of Family Growth (NSFG)
• Medical Expenditure Panel Survey (MEPS)
• National Health and Nutrition Examination Survey
  (NHANES)

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Alternative Levels of Linkage

• Respondent level Same respondents in both
  surveys
• HH (address) level Same HH - but possibly
  different respondents
• Segment level Same second-stage units (segments)
  - but different HH within segments
• PSU level Same first-stage units (PSUs) - but
  different segments within PSUs

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Key Features of the NHIS

• Survey of the U.S. civilian noninstitutionalized
  population
• Continuously conducted since 1957
• Face-to-face interviews
• Broad range of health issues
• Stratified multistage area probability sample
  design
• Sample redesign every 10 years following
  decennial census

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NHIS Sample Design 1995-2004

• Oversampling of black and Hispanic persons
• State and Census region stratification
• 358 sample PSUs
• Sample partitioned into subdesigns
• Assignment of sample to weekly and quarterly
  subsamples
• 4 panels or subsamples

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National Survey of Family Growth (NSFG)

• Survey of women 15-44 years of age
• Reproductive history and health of women and
  children
• First national household survey linked to the
  NHIS

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National Survey of Family Growth (NSFG)

• Sample of women for NSFG Cycles IV (1988) and V
  (1995) selected from women previously sampled in
  the NHIS
• NSFG IV sample selected from 156 NHIS PSUs based
  on the 1985-1994 design
• NSFG V sample selected from all 198 PSUs based on
  the 1985-1994 design

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Advantages of NHIS NSFG Linked Design

• Avoids the costs of listing and screening with
  identification in the NHIS of HH containing women
  15-44 years of age
• Particularly useful for the oversampling of
  Hispanic and non-Hispanic black women

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Advantages of NHIS NSFG Linked Design

• Linked analyses, combining NHIS and NSFG data,
  can be done
• Use of NHIS data to adjust for nonresponse to the
  NSFG to compute the sample weights
• Use of NHIS data on income to help impute NSFG
  missing income data

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Limitations of NHIS NSFG Linked Design

• Size of the NSFG sample is limited by the size of
  the NHIS sample
• Number of women aged 15-44 cannot exceed the
  number of women in the NHIS sample (without
  supplemental area sample)
• Accumulation of more than one year of NHIS data
  may be needed to meet sample size requirements

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Limitations of NHIS NSFG Linked Design

• Need to trace persons who moved since their NHIS
  interview (moving rates vary by age)
• Potential for decreased response rates
• Tracing costs and lack of clustering of NHIS PSUs
  may increase survey costs
• Need for high completion rate in the NHIS of
  locator data (name, SSN, contact persons)
• Impact on field data collection

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National Health Nutrition Examination Survey
(NHANES)

• Collection of health and nutrition data via
  personal household interviews and physical
  examinations
• Periodic survey up until 1994
• Continuous annual survey starting in 1999
• Annual estimates for broad subdomains
• Linkage with other surveys (NHIS and CSFII)

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National Health Nutrition Examination Survey
(NHANES)

• Possible linkage at
• PSU level
• HH (address) level
• Person level
• Survey content level

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Advantages of NHIS NHANESLinked Design

• Common sampling frame
• Reduced cost of screening
• Enhanced analytic capabilities and modeling
• Correlation of self-reported disease incidence
  and examination results
• Enhanced nonresponse adjustment

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Limitations of NHIS NHANES Linked Design

• Survey operation constraints
• Standardized environment, equipment, and data
  collection through Mobile Exam Centers
• Logistics of moving/setting up exam center

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Limitations of NHIS NHANES Linked Design

• Fixed number of PSUs per year (about 15)
• Larger PSUs (single counties) needed in NHANES
  than NHIS
• Fixed sample size per PSU (about 450 examined
  persons)

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Limitations of NHIS NHANES Linked Design

• Fixed sample size requirements by age, sex, and
  race/ethnicity
• Tracking and tracing (approximately 17 of
  population moves every year)
• Linkage at sample or address level not possible
  without supplemental independent area sample

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Medical Expenditure Panel Survey (MEPS)

• Type, frequency of use, and cost of health
  services
• How health services paid for
• Cost, scope, and breadth of health insurance
  coverage

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1996 MEPS Sample Design

• 1996 MEPS sample linked to 1995 NHIS subsample
  (2nd and 3rd quarter from 2 panels)
• 1995 NHIS subsample nationally representative
• Minority oversample
• Fixed precision requirements

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1996 MEPS Sample Design

• 195 PSUs
• 1,675 area segments
• 10,597 NHIS dwelling units selected for the MEPS

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1996 MEPS Round 1 Response Rates

• 1995 NHIS response rate (93.9)
• 99.6 of NHIS eligible units fielded
• MEPS Round 1 response rate (83.1)
• Overall response rate of 77.7

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MEPS Design Improvements

• Savings achieved through elimination of
  independent sample and screening
• Analytical capacity enhanced
• Data linkage to NHIS
• Longitudinal 2-year panel
• Annual expenditure survey
• Efficiencies through continuous operation
• Improved nonresponse adjustments

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Limiting Features of the MEPS Linkage to NHIS

• Lower response rates relative to NMES (1987)
• Greater restrictions in access to data related to
  confidentiality of data
• Lower cost savings in non-peak years with limited
  oversampling of specific population subgroups

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Limiting Features of the MEPS Linkage to NHIS

• Need to track movers and re-enumerate NHIS
  households to capture changes in HH composition
• Dispersion of NHIS PSUs constrains flexibility of
  survey operations

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Other Survey Design Integration Strategies

• Use of NHIS questions in other surveys
• Integration of NHIS for state-level data
• Use of NHIS data to adjust for noncoverage of
  nontelephone HHs in a large RDD survey
• Dual frame NHIS/RDD design

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National Immunization Survey

• Large ongoing random-digit-dialing (RDD) survey
  (initiated in 1994)
• Provide vaccination coverage data at state and
  local level (50 states and 28 urban areas)
• Target population children 19-35 mo. (lt 5 of
  HHs in U.S.)

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NIS Data Collection

• Over 2 million telephone numbers sampled per year
  
• 1.6 million numbers dialed per year after
  pre-screening for business and non-working
  numbers
• About 929,000 with working numbers
• 900,000 screened for children 19-35 months
• 36,000 eligible HHs interviewed

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NIS and NHIS Integration

• Same questions on immunizations
• Immunization information on both phone and
  non-phone HHs in the NHIS
• Use of ratio of immunization status in phone and
  non-phone HHs from the NHIS used to adjust for
  non-telephone coverage in the NIS

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Expansion of the NIS

• Use of large random sample of telephone numbers
• Collect more broad based health and welfare data
  for adults and children
• New survey State and Local Area Integrated
  Telephone Survey (SLAITS)

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Key Features of SLAITS

• Consistent with DHHS survey integration plans
• Decreased survey costs
• Use of questions from NHIS and other national
  surveys
• Use of NHIS data to adjust for nontelephone
  coverage
• Comparisons across states and with national data
• Complements other state and local surveys

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Summary

• Survey integration - goal for HHS surveys
• Coordination of survey efforts
• Fill gaps in data
• Enhanced analyses
• Efficiencies in sampling, data collection,
  questionnaire design, and survey operations
• Progress on implementing MEPS-NHIS linkage

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Summary

• Progress on implementing NHANES on annual basis
  and linked to NHIS
• Progress on capacity for State level data
• Ongoing evaluations and research on
  methodological issues for the integration of
  health surveys

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Methodological Research Integrated Health Surveys

• Redesign NHIS with linkage as major goal
  (optimize NHIS design for family of surveys
  linked to it)
• Reduce percent of cases with missing recontact
  information
• Reduce time lag between surveys to reduce tracing
  and improve response rates

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Methodological Research Integrated Health Surveys

• Continued research on capacity for State-level
  estimates
• Assess risk of new sources of survey error
• Combined effect of area frame coverage and
  nonresponse in NHIS
• Recontact of NHIS respondents

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