An overview of the National Asthma Survey (NAS)

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An overview of the National Asthma Survey
(NAS)

• Kathleen S. OConnor, MPH
• National Center for Health Statistics
• Division of Health Interview Statistics
• Special Populations Survey Branch
• State and Local Area Integrated Telephone Survey
  (SLAITS)
• July 13, 2004

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Objectives

• Examine the health, socioeconomic, behavioral,
  and environmental predictors that relate to
  better control of asthma
• Characterize the content of care and health care
  experiences of persons with asthma
• Provide detailed information about asthma
  treatment and control

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Background and unique features

• Sponsored by National Center for Environmental
  Health (CDC)
• Complements and extends survey work from other
  large Federal survey and surveillance systems
  such as the NHIS, NHANES, and the BRFSS
• Adds depth to the existing body of asthma data
• Helps address critical questions surrounding the
  health, physical environment, and experiences of
  persons with asthma
• Assists researchers in understanding factors that
  relate to better control of asthma

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Unique features

• Comprehensive snapshot
• Includes BRFSS asthma variables for direct
  comparison
• Indicators are consistent across the samples
  (same instrument)
• Adults and children

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Methodology

• Random-Digit-Dial (RDD) telephone survey
• National Immunization Survey (NIS) sampling
  frame
• 20 25 minutes in length excluding the NIS
  interview (NAS after the NIS)
• Also had a NAS-only component that did not
  receive the NIS

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Methodology

• Multiple samples
• National
• Four states (AL, CA, IL, TX)
• Fielded February 27, 2003 February 20, 2004
  (national)
• Fielded March 1, 2003 March 10, 2004 (states)
• Adjusted weights (non-response bias, non-coverage
  of non-telephone households)

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NAS interview process

• National
• All HH members eligible
• One person (adult or child) randomly selected per
  HH regardless of asthma status
• Collected detailed information on asthma status,
  history, knowledge, management, and home
  environment for persons with asthma
• Collected insurance, home environment, and family
  history for persons with and without asthma
• Four States (AL, CA, IL, TX)
• Screened all household members for asthma
• In asthma HHmax one child and one adult per HH
  were randomly selected for detailed questionnaire
  (child MKP report, adult self report)

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• A brief stroll through the questionnaire
• select indicators by survey domain

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Asthma Introduction

• Lifetime and current asthma status
• Age and gender of selected person
• Respondent relationship

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Detailed asthma screening

• Age at diagnosis
• Length of time since last discussion with doctor
  about asthma
• Length of time since taking asthma meds
• Length of time since experiencing asthma symptoms

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History of asthma

• Any symptoms past 30 days
• Continuity of symptoms throughout day
• Difficult sleep due to asthmapast 30 days
• Past 2 weekshow many days symptom free
• Past 12 months--asthma episodes
• Past 3 monthsnumber of asthma attacks
• Length of most recent attack
• Relative length of most recent attack

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Health care utilization

• Most Qs past 12 months
• Insurance coverage
• Doctor visit for asthma
• ER/urgent care visits
• Urgent doctor visits due to worsening symptoms
• Overnight stays in hospital
• After last hospital stay did HCP talk about how
  to better control asthma to prevent episodes or
  hospitalization
• Unable to work or carry out usual activities
• Missed school days
• Limited usual activities

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Knowledge of asthma

• MD or HCP ever taught
• Recognition of early signs/symptoms of attack
• What to do during attack
• How to use a peak flow meter
• Presence/absence of asthma management plan
• Taken course on how to manage asthma

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Modifications to the environment

• Use of air cleaner, purifier, dehumidifier,
  exhaust fan in kitchen, gas stove
• Mold inside home
• Indoor pets
• Cockroaches in home
• Fireplace or wood burning stove
• Unvented gas logs, fireplace, or stove
• Smoking inside home

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Environment continued

• Has HCP ever advised R to change things inside
  home, school, or work to improve asthma
• Use of mattress cover or pillow to control dust
  mites
• Carpeting or rugs in bedroom
• Temperature of wash water for sheets and
  pillowcases
• Exhaust fan in bathroom
• Pet allowed in bedroom?
• Cigarette smoking, frequency
• Current employment status
• Job exposure to chemicals, smoke, fumes or dust

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Medications

• OTC meds
• Ever used prescription inhaler
• HCP taught how to use inhaler
• Names, amount, and how often for each med (pill
  or syrup, inhaler, Nebulizer)
• Spacer use

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Family history of asthma

• Anyone else in HH w/asthma
• biological siblings
• Asthma in biological parents, brothers, sisters,
  grandparents if so, whom

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Demographics

• Race, ethnicity
• Education
• Height, weight for BMI calculation
• Birth weight of selected child
• Income

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Timeline

• Data cleaning, review, weighting Summer 2004
• Public Use data files will be released as soon as
  they have been prepared and the necessary reviews
  and approvals have been obtained, including
  review by the NCHS Disclosure Review Board
• Public Use File release Anticipated Late 2004
  or Early 2005

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For more information

• www.cdc.gov/nchs/slaits.htm
• SLAITS listserve (directions on website)
• slaits_at_cdc.gov
• 301 - 458 - 4181
• Thank you for your interest!