Two HCUP variables indicate initial encounters for injuries: I10_INJURY is used to indicate at least one injury is reported in the first-listed or later diagnoses; I10_MULTINJURY is used to indicate that more than one injury is reported, regardless of diagnosis position.

The availability of these data elements varies over time:

• For data year 2015, the data elements are available only on the HCUP State databases.
• For data year 2016, the 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 year 2017-2018, the data elements are available only on the HCUP Nationwide Emergency Department Sample (NEDS).
• Beginning in data year 2019, the data elements are available on the HCUP State databases and the NEDS.

Starting in Data Year 2020, Initial Encounter Injuries are Identified by the Clinical Classifications Software Refined (CCSR) for ICD-10-CM Diagnoses

Starting with v2021.1 of the CCSR for ICD-10-CM, the injury categories align with the 2020 ICD-10-CM Injury Diagnosis Framework for Categorizing Injuries by Body Region and Nature of Injury. These CCSR categories include INJ001-INJ027 and INJ032.

From Data Year 2017 to 2019, ICD-10-CM Diagnosis Codes Used to Identify Injury Discharges

Below is a list of the ICD-10-CM diagnosis codes used to identify injuries starting in data year 2017, only codes indicating an initial encounter (with a 7th character of A, B, C, or missing) are considered:

• S00-S99 series: Injuries to the head; neck; thorax; abdomen, lower back, lumbar spine, pelvis and external genitals; shoulder and upper arm; elbow and forearm; wrist, hand and fingers; hip and thigh; knee and lower leg; ankle and foot.
• T07-T34 series: Injuries involving multiple body regions; injury of unspecified body region; effects of foreign body entering through natural orifice; burns and corrosions of external body surface, specified by site; burns and corrosions confined to eye and internal organs; burns and corrosions of multiple and unspecified body regions; frostbite
• T36-T50 series with a 6th character of 1, 2, 3, or 4: Poisoning by drugs, medicaments, and biological substances
• T36.9, T37.9, T39.9, T41.4, T42.7, T43.9, T45.9, T47.9, and T49.9 with a 6th character of X and a 5th character of 1, 2, 3, or 4: Poisoning by drugs, medicaments, and biological substances
  • In the 2017 NEDS, the criteria to identify injuries was missing this range of codes. The exclusion of these codes resulted in 3,775 records (0.01 percent of the 2017 NEDS) as not being identified as injury-related records.
• T51-T76 series: Toxic effects of substances chiefly nonmedicinal as to source; other and unspecified effects of external causes: radiation sickness, unspecified; effects of heat and light; hypothermia; other effects of reduced temperature; effects of air pressure and water pressure; asphyxiation; effects of other deprivation; adult and child abuse, neglect and other maltreatment, confirmed; other and unspecified effects of other external causes; adult and child abuse, neglect and other maltreatment, suspected
• T79 series: Certain early complications of trauma, not elsewhere classified
• M97 series (valid as of October 1, 2016) or T8404 series (valid prior to October 1, 2016): Periprosthetic fracture around internal prosthetic joint
• O9A2-O9A5 series: Injury, poisoning, physical abuse, sexual abuse, psychological abuse, and other consequences of external causes complicating pregnancy, childbirth and the puerperium

It should be noted that ICD-10-CM codes in the range of T36-T50 with a 6th character of 5 or 6 are excluded from the criteria to identify injuries. These codes are specific to adverse effects and underdosing of drugs, medicaments and biological substances.

Data Year 2015 ICD-10-CM Diagnosis Codes Used to Identify Injury Discharges

Records with injuries are identified by ICD-10-CM diagnosis code using translation of the ICD-9-CM scheme recommended by the State and Territorial Injury Prevention Directors Association (STIPDA). Below is a list of the ICD-10-CM diagnosis codes used to identify injuries for data year 2015:

• First three digits of S00-T34: Fractures; dislocations; sprains and strains; intracranial injury; internal injury of thorax, abdomen, and pelvis; open wound of the head, neck, trunk, upper limb, and lower limb; injury to blood vessels; late effects of injury, poisoning, toxic effects, and other external causes, Superficial injury; contusion; crushing injury; effects of foreign body entering through orifice; burns; injury to nerves and spinal cord; traumatic complications and unspecified injuries, initial or subsequent encounter or sequela; excluding those of complications of surgical and medical care.
• First three digits of T36-T50: Poisoning of drugs, medicaments and biological substances, initial or subsequent encounter or sequela; excluding adverse effects and underdosing of drugs, medicaments and biological substances (codes with the 6th character of 5 or 6; or with the 5th-6th characters of 5X or 6X).
• First three digits of T51-T75: Toxic effects of substances chiefly nonmedicinal as to source; other and unspecified effects of external causes, initial or subsequent encounter or sequela.
• First three digits of T76: Adult and child abuse, neglect and other maltreatment, suspected, initial or subsequent encounter or sequela.
• First three digits of T79: Certain early complications of trauma, initial or subsequent encounter or sequela.

For data prior to the fourth quarter of 2015, the multiple injury flag is stored in the data element INJURY to indicate the use of the ICD-9-CM coding system.