California Emergency Department Diagnosis and Procedure Code Counts

Statewide counts for every diagnosis, procedure, and external cause of injury code reported on hospital emergency department data. Diagnosis and external cause codes use ICD-9-CM or ICD-10-CM, while procedure codes use CPT-4. The dataset is maintained by the State of California and was last updated in November 2025.

Use Cases

• Analyze the frequency of specific diagnosis codes across California emergency departments to identify prevalent conditions.
• Examine trends in procedure code counts to understand common emergency department interventions.
• Study external cause of injury code distributions to inform public health initiatives on accident prevention.
• Compare code utilization before and after the ICD-10 adoption date of October 1, 2015.

Strengths

• Covers all diagnosis, procedure, and external cause codes reported for emergency departments across the entire state of California.
• Includes codes from two major classification systems: ICD-9-CM/ICD-10-CM for diagnoses and CPT-4 for procedures.
• Updated as recently as November 2025, indicating recent maintenance.

Limitations

• Contains only aggregated counts, not individual patient-level records, limiting granular analysis.
• The specific number of rows, columns, and total record count is unknown.
• Data is provided in XLS and ZIP formats, which may require specific software for access and parsing.

Provenance

Source

State of California, Department of Health Care Access and Information (HCAI).

Collection Method

Aggregated from hospital emergency department data submissions.

Time Range

Temporal coverage is not specified, but the dataset notes the ICD-10 transition effective October 1, 2015.

Freshness

Last updated on 2025-11-23.

Geography

State of California, USA.