Selected Common Discharge Data Elements and their Structure

Data Element


Primary diagnosis code fields*

A single field populated with an ICD-10-CM diagnosis code.

For hospitalization datasets: The official name of this field is the “Principal Diagnosis” field. The Uniform Hospital Discharge Dataset (UHDDS) definition for principal diagnosis is “the condition established after study to be chiefly responsible for occasioning the admission of the patient to the hospital for care”.

For ED datasets: This field is often referred to as the “first-listed diagnosis” rather than the “principal diagnosis”, and the code found there does not have the same significance. In the ED, medical coders must “list first the ICD-10-CM code for the diagnosis, condition, problem, or other reason for encounter/visit shown in the medical record to be chiefly responsible for the services provided”, however if a physician has not confirmed the patient’s diagnosis, the coder can list a symptom in this field.

Secondary diagnosis code fields

These fields are populated with ICD-10-CM diagnosis codes representing additional conditions present at the time of the ED visit or inpatient stay. The available number of diagnosis fields varies by jurisdiction. The order of codes found in these fields has no significance. 

External cause of injury fields

These fields are populated with ICD-10-CM external cause of injury codes, but may also include activity, place, or status codes. Some jurisdictions have more than one external cause of injury field for each record, while others have only one dedicated external cause of injury field, and others have no dedicated fields but instead intersperse external cause of injury codes within the available diagnosis fields.

Demographic fields

Datasets may include several fields for demographic information including race, gender, and age.

Date of discharge field

This field provides the date the patient was discharged. For injury surveillance, epidemiologists should use the discharge date to classify cases into time periods. 

Discharge status field

This field provides codes that indicate the status of the patient at time of discharge, for example, “routine/discharged home”, “left against medical advice, “discharged/transferred to short-term facility”, or “dead”.

*See the “Data Dictionary for General Injury Validation Datasets” for examples of how these and other fields may be populated in a discharge dataset