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Last Edited: 6/24/2014

Asthma: Where to Find Data

A number of programs contribute to the effort to understand asthma in California by collecting, analyzing, and disseminating data and information. 


The California Environmental Health Tracking Program (CEHTP) aims to provide and improve data and information to support efforts to reduce asthma related to the environment.  Our data query allows you to create your own table, charts, and maps using data on asthma hospitalization and emergency deparment visits.  These measures were developed in a joint effort by CEHTP, the CDC Tracking Program and grantees, the State Environmental Health Indicators Collaborative, California Breathing, and other stakeholders.


There are many other efforts at the state and national level to collect data about asthma.  As described in How is it Measured?, asthma is a complex disease that can be measured in many ways.  Below is a list of different asthma data sources at the state and national level.  Together, these data collection efforts help to better form a picture of how asthma affects us. 

Other asthma data for California

California Breathing, the state asthma surveillance program, analyzes and disseminates asthma data and information for purposes of reducing the overall burden of asthma. A few of CB’s more recent publications with asthma data include:


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National Data

Nationally, asthma surveillance data come from a variety of data sources and include collection of prevalence rates, days of limited activity, physician visits, hospitalizations, and deaths due to asthma. Theses data sources include population-based surveys, vital statistics databases, and healthcare utilization surveys.


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Population-based surveys

For prevalence estimates, population-based surveys are the most commonly used data source. These surveys are typically telephone administered to a random sample of the population. Based on this sample, prevalence estimates can be made for certain geographic areas (e.g. state) and segments of the population (e.g. African-Americans).

Each survey may have different wording for the asthma questions, or the questions could change year to year. Wording differences are important to understand when analyzing the data because the way a question is worded can affect the response of the participant.

Here’s a list of population-based surveys used in the U.S. to collect data on asthma:

  • Behavioral Risk Factor Surveillance System (BRFSS)
    • BRFSS is a telephone administered survey given to a random sample of U.S. residents sampled by state. The survey includes questions on major behavioral outcomes and risks among adults, including asthma. The BRFSS has included asthma questions since 1999 and allows state estimates of asthma prevalence.
  • BRFSS Asthma Call-back Survey
    • This survey is administered to those respondents in the BRFSS survey who reported having asthma. The survey asks extensive questions on asthma symptoms and medication utilization. In 2005, 3 states pilot tested the Call-back survey, in 2006 25 states participated, in 2007 35 states participated, and in 2008 38 states participated.  California is among the participating states.
  • National Asthma Survey (NAS)
    • The NAS was conducted in 2003 to examine the health, socioeconomic, behavioral, and environmental predictors that relate to better asthma control. The NAS was adapted to become the BRFSS Asthma Call-back Survey.
  • National Survey of Children’s Health (NSCH)
    • The NSCH was conducted in 2003-2004 and again in 2007 to examine the physical and emotional health of children ages 0-17, including an extensive set of questions about asthma.
  • National Health Interview Survey (NHIS)
    • The NHIS is the principal source of data and information on the health of the U.S. population. The NHIS has been conducted since 1957 although asthma questions weren’t introduced until 1997
  • National Health and Nutrition Examination Survey (NHANES)
    • The NHANES was designed to collect health and diet information on the U.S. population. NHANES consists of a home interview along with health tests conducted in a Mobile Examination Center (MEC). Various versions of asthma questions have been included in NHANES since 1971 and beginning in 2007, a respiratory test was included in the health tests conducted in the MEC
  • National Longitudinal Surveys (NLS)
    • The NLS is conducted by the U.S. Department of Labor, Bureau of Labor Statistics designed to gather information on labor market activities and other significant life events of several groups of men and women. In 1986, a separate survey was developed to gather demographic and development information on the children born to the female respondents. This survey included questions on asthma.
  • International Study of Allergies and Asthma in Children (ISAAC)
    • ISAAC was formed in 1991 to facilitate research into asthma and allergies in children by promoting a standard methodology that is used internationally.

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Vital statistics data:

In addition to prevalence data, asthma mortality data is collected at a national level using a national vital statistics data system.

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Health care utilization data:

Asthma-related hospitalizations and emergency department visits are also collected and available on a national level.

  • National Hospital Discharge Survey (NHDS)
    • The NHDS, conducted by the National Center for Health Statistics since 1965, collects data from a sample of approximately 270,000 inpatient records from a national sample of 500 hospitals. Using this data, researchers can estimate hospitalizations due to asthma nationally and by region.
  • National Hospital Ambulatory Medical Care Survey (NHAMCS)
    • The NHAMCS is designed to collect data and information on the utilization and provision of ambulatory care services at hospital emergency and outpatient departments, based on a national sample of hospitals. Researchers can use NHAMCS data to estimate emergency department visit rates due to asthma.
  • CDC National Environmental Health Tracking Program (EHTP) Portal
    • The National EHTP portal provides consistent data and measures for asthma hospitalizations for the states funded by the CDC EPHT program. The asthma hospitalization data presented on the national portal are gathered by each EPHT program from each state’s hospital discharge database.

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