The mechanism of injury is determined by the External Cause of Morbidity Codes and is consistent with the classification system used by the Centers for Disease Control and Prevention (CDC) and documented at www.cdc.gov/nchs/injury/injury_tools.htm.

Beginning in the 2018 NEDS and the 2019 State databases, HCUP includes 12 data elements that identify the mechanism of the injury: cutting/piercing, drowning, falling, fire, firearm, machinery, motor vehicle traffic, natural/environmental, overexertion, poisoning, suffocation, and being struck by or against. HCUP also includes three data elements that identify the intent of the injury: unintentional, assault, and self-harm. If multiple injuries are reported, more than one mechanism and intent may be identified.

For the fourth quarter of 2015 through 2017, the mechanism of injury data elements are not included on any HCUP databases as HCUP worked with the Centers for Disease Control and Prevention (CDC) to finalize the coding criteria for ICD-10-CM diagnoses.

For data prior to the fourth quarter of 2015, the mechanism of injury of natural or environmental, including bites/stings is stored in the data element INJURY_NATURE to indicate the use of the ICD-9-CM coding system.