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Last Edited: 9/29/2010

Asthma Indicators

Learn more about the different ways in which asthma is measured:


Prevalence

How is asthma prevalence measured?

Prevalence is estimated through telephone surveys of a random sample of the population.

    • Adult survey respondents are asked if they have ever been diagnosed with asthma by a health care provider
    • For children, some surveys allow teens (older than 13 years of age) to respond for themselves, while other surveys ask the adult respondent about the asthma diagnoses of all the children living in their household

This is a measure of lifetime asthma prevalence. Respondents are also asked if they or their children still have asthma or still experience asthma symptoms, a measure of current asthma prevalence.

 

 Where do the data come from?

Prevalence data in California come from two surveys:

    • The Behavioral Risk Factor Surveillance System (BRFSS) is a survey that is nationally coordinated by the Centers for Disease Control and Prevention and conducted in California by the Survey Research Group of the CDPH
    • The California Health Interview Survey (CHIS) is a statewide survey conducted by University of California at Los Angeles in collaboration with the California Department of Public Health, the Department of Health Care Services, and the Public Health Institute

To see the prevalence estimates in California, see California Breathing’s Asthma Burden Report (PDF)

 

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Severity

How is asthma severity measured?

There is no routine system for collecting clinical asthma severity information in California.  The Behavioral Risk Factor Surveillance System (BRFSS)and the California Health Interview Survey (CHIS) do not include questions about asthma severity as diagnosed or assessed by a health care provider.  However, the surveys include questions on asthma symptoms and healthcare.  This information is used to assess how asthma affects the people who have it.

Survey topics include:

    • Number of school or work days missed due to asthma
    • Days of activity limitation due to asthma
    • Frequency of symptoms and asthma attacks
    • How well asthma is managed

Where do the data come from?

Asthma severity is estimated from two surveys:

    • BRFSS has been conducted in California since 1984
      • Some years have included very detailed information about asthma severity
      • However, the sample size of BRFSS is too small to get reliable estimates for population subgroups such as race/ethnicity groups
    • CHIS has only been conducted bi-annually since 2001, but it has a much larger sample size and can provide reliable estimates by race/ethnicity and county

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Scheduled and Unscheduled Office Visits

How are office visits measured?

Scheduled or unscheduled office visits could ideally be measured by identifying asthma-related visits in medical records, though health care providers are not required to report this information to the State.  Another way to gather information on office visits is through telephone administered surveys.

 

 Where do the data come from?

Currently, there is no system that gathers medical record data to track asthma-related office visits in California.

    • The Behavioral Risk Factor Surveillance System (BRFSS) asks people with asthma how many office visits they have had in the past year
      • However, self-reported information may be inaccurate
      • This question also does not provide details about the full extent of health care usage for asthma, nor the type and quality of care that is given

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Emergency Department/Urgent Care Visits

How are asthma emergency department visits measured?

An asthma-related emergency department (ED) visit is measured by examining hospital records on ED visits and identifying the visits that had an asthma diagnosis. Some ED visits may result in a hospitalization.

 

 Where do the data come from?

Hospitals are required to report all ED visits to the California Office of Statewide Health Planning and Development (OSHPD).

    • OSHPD began collecting and maintaining ED data in California in 2005
    • The OSHPD Emergency Department/Ambulatory Surgery (ED/AS) databases include information such as age, gender, race/ethnicity, and diagnosis

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Hospitalizations

How are asthma hospitalizations measured?

An asthma-related hospital admission is identified by looking at hospitalization data and selecting the admissions that had an asthma diagnosis.

 

Where do the data come from?

Hospitals are required to report all hospitalizations to the California Office of Statewide Health Planning and Development (OSHPD).

    • OSHPD maintains data on asthma hospitalizations in its Patient Discharge Databases (PDD)
    • These datasets include information such as age, gender, race/ethnicity, diagnosis, and charges

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Mortality

How is asthma mortality measured?

An asthma death is identified by looking at death records data and selecting cases that had asthma listed as the underlying cause of death.

 

Where does the data come from?

Data on asthma deaths come from death certificate data compiled by the California Department of Public Health, Center for Health Statistics (CHS).

    • These data are available from CHS from 1960 to present
    • These data sets have a record for each death in California. Records include information such as age, gender, race/ethnicity, and cause of death

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