Asthma Emergency Department Visit Rates in California by County and ZIP Code

Asthma emergency department visit counts and rates per 10,000 residents for California. Data is stratified by county, ZIP code, age group, and race/ethnicity. The dataset originates from the Department of Health Care Access and Information database of all licensed hospitals in the state.

Use Cases

• Analyze asthma ED visit rate disparities across race/ethnicity categories such as white, black, and Hispanic populations.
• Compare asthma ED visit rates per 10,000 residents across different age groups like 0-4, 5-17, and 65+ at the county level.
• Map geographic health outcomes by correlating ZIP code-level visit rates with other demographic or environmental datasets.
• Investigate temporal trends in asthma ED visits, noting the 2015 ICD code transition from ICD9-CM to ICD10-CM.

Strengths

• Data is stratified by multiple demographic dimensions, including 7 age groups and 5 race/ethnicity categories.
• Coverage includes all licensed hospitals in California, providing a complete statewide picture of asthma ED visits.
• Provides both raw counts and standardized rates per 10,000 residents for comparative analysis.

Limitations

• Data before and after the 2015 ICD code transition are not directly comparable, limiting longitudinal analysis across that year.
• Rates are based on total visit counts, not unique individuals, which may overrepresent frequent visitors.
• The dataset is based solely on primary discharge diagnoses, potentially missing visits where asthma was a secondary condition.

Provenance

Source

Department of Health Care Access and Information emergency department database.

Collection Method

Derived from primary discharge diagnosis codes from all licensed hospitals in California.

Freshness

Last updated in December 2025.

Geography

State of California, with county-level and ZIP code-level granularity.