Concept: Injuries - Injury Coding Using ICD-9 and ICD-9-CM

Introduction

This concept describes the use of ICD-9 injury codes that were used in the Assessing the Health of Children in Manitoba: A Population-Based Study (2001) deliverable by Brownell et al. (2001).

The ICD-9 and ICD-9-CM coding systems have two different sections related to injury codes. The first section describes the effects of injury and poisoning and use ICD codes in the range 800 - 999. The second section describes the external causes of injuries, poisoning and other adverse effects, and these are referred to as E-codes, ranging from E800 - E999. The E-codes describe the events, circumstances and conditions that cause the effects or injuries coded elsewhere in the data.

Both sets of injury codes can be present on individual records in the Hospital Abstracts data and in the Vital Statistics Mortality data. See the Effects of Injury and Poisoning section below for more information. Injury hospitalizations may be identified by the presence of one or more E-codes in the diagnosis fields. The variable ECLASS groups the E-codes into 23 categories, and a value between "01" and "23" indicates the presence of an E-code diagnosis. For more information on how injury codes are used in the Vital Statistics Mortality data, please read the Vital Statistics - Use of ICD-9 Codes Identifying Cause of Death concept.

For a more complete listing of external cause of injury codes (E-codes), see the External Cause of Injury Codes and Categories concept.

Sample of Motor Vehicle External Cause of Injury Codes (E-codes from ICD-9-CM/ICD-9))

The following list provides a sample of the motor vehicle injury E-codes used in the Assessing the Health of Children in Manitoba: A Population-Based Study (2001) deliverable, based on the report, Injury Deaths and Hospitalizations Province-wide and by Region: 1996 and Trends .


• E810: Motor vehicle traffic accident involving collision with train
  
• E811: Motor vehicle traffic accident involving re-entrant collision with another vehicle
  
• E812: Other motor vehicle traffic accident involving collision with motor vehicle
  
• E813: Motor vehicle traffic accident involving collision with other vehicle
  
• E814: Motor vehicle traffic accident involving collision with pedestrian
  
• E815: Other motor vehicle traffic accident involving collision on the highway
  
• E816: Motor vehicle traffic accident due to loss of control, without collision on the highway
  
• E817: Noncollision motor vehicle traffic accident while boarding or alighting
  
• E818: Other noncollision motor vehicle traffic accident
  
• E819: Motor vehicle traffic accident of unspecified nature
  
• E822: Other motor vehicle nontraffic accident involving collision with moving object
  
• E823: Other motor vehicle nontraffic accident involving collision with stationary object
  
• E824: Other motor vehicle nontraffic accident while boarding and alighting
  
• E825: Other motor vehicle nontraffic accident of other and unspecified nature

See the complete listing of E-Codes used in the Assessing the Health of Children in Manitoba: A Population-Based Study (2001) deliverable in Table G.5 in the Glossary of this report.

Effects of Injury and Poisoning

Effects of injury and poisoning are a separate category in the ICD-9 system (ICD-9 800-999, Injury and Poisoning). By using codes from each section, both the circumstances leading to an injury and the effects of the injury can be recorded. A fall resulting in a fracture would be recorded both as a fall (E880-E888) and a fracture (ICD 800-829).

A hospital claim with a diagnosis in the range 800-999 should also have an E-code describing the cause of the injury. Note, however, that the reverse is generally not true: a record with an E-code does not require a corresponding diagnosis in the range 800-999. For example, E906.0, dog bite, could be associated with a diagnosis of 682.4, cellulitis of the hand. A definition of injuries based solely on the range 800-999 would miss this diagnosis, even though it is clearly the result of an injury.

For this reason, a definition of injuries based on E-codes is preferable to one based on ICD 800-999.

Transfers

A serious injury is likely to involve several hospitalizations if the person is treated on an emergent basis, transferred for surgery, and then transferred again for recovery. If an accurate count of injury events, rather than hospitalizations, is desired, then some effort to determine episodes of care should be made.

The episode macro will identify which records are associated with the same event. Once the records are grouped by episode, an accurate count of the separate events can be made.

Definition of Injuries in the Child Health Deliverable (2001)

Injury events in the Assessing the Health of Children in Manitoba: A Population-Based Study (2001) deliverable were defined as all inpatient hospital records for Manitobans aged 0 to 19 with a value of ECLASS greater than 00 and not equal to 10, 11 or 18.

This definition only looks at events occurring on inpatient records because there was some concern about the reliability of day-procedure coding in rural hospitals.

Categories 10, 11 and 18 capture nearly all of the iatrogenic injuries, but some are unavoidably included in other categories. Category 8, Accidental poisoning by drugs, includes poisoning resulting from the wrong drug or an overdose of the correct drug given by a physician.

It is impossible to determine how the drugs were administered from the ICD codes in Category 8, so this category was left in the Child Health definition even though it includes some injuries resulting from physician error.

Coding

ICD-9-CM E-codes are only identified in hospital abstracts data up to the end of April, 2004, so the event file must be based on hospital inpatient or day-procedure records. The diagnoses coded in the Medical Services / Physician Claims data are never prefixed with an E.

SAS Code

The following code will identify all records with an injury diagnosis according to the Child Health definition.

if 0<=age<=19; *Age at date of admission;

if transact='1'; * Keep inpatient records only;

if ('01'<=eclass<='09' or '12'<=eclass<='17'or '19'<=eclass<='23') then injury=1;

MORE INFORMATION

• Manitoba Health (1998). Manitoba Health in collaboration with IM-PACT. Manitoba Injury Data Resource. Injury Deaths and Hospitalizations Province-wide and by Region: 1996 and Trends. Epidemiology Unit, Public Health Branch, Manitoba Health, Winnipeg.