Centers for Disease Control and Prevention National Center for Health Statistics ICE on Injury Statistics, Sept 2006 Margaret Warner, PhD Office of Analysis and Epidemiology for ICE on Injury Statistics working group Selecting a main injury from multiple causes of death

Current MRG recommendations for selecting a main injury 1) Eliminate trivial injuries and superficial injuries from consideration. 2) If obvious causal sequence, select injury which led to death. 3) Select from among remaining injuries using severity ranking (e.g. Precedence list). 4) Select first mentioned if several at same level of severity.

ICE working group concerns with current recommendations Method for eliminating unspecified injuries Example: S26.9 Injury of heart, unspecified Injuries occurring simultaneously (i.e. sequential order is not inherent) Example: Car crash with multiple specified injuries on each line of death certificate Consideration of external cause in determining main injury if indicates something about nature Example: External cause: car crash Main injury: poisoning?

Injury deaths in US, 2003 US Multiple cause data: 66% had 1 injury listed 34% had 2 or more injuries listed 10% had 2 or more injuries on lowest used line in Part I of death certificate Note: The lowest used line in Part I of the death certificate is the end of the causal sequence leading to death If the death certificate is filled out properly.

General guidelines for ranking severity Goal: Group injury codes into similar levels of severity Groups based on nature and body region Severity based on threat to life 6-7 ordinal levels of severity Note that many injuries will be at same level of severity

Implementation of guidelines 1) Group ICD codes into nature and body region categories using a modified Barell Matrix (i.e. mapped to ICD-10 Injury Mortality Diagnosis Matrix 2) Find morbidity data source with disposition status of alive or dead 3) For each body region and nature combination, calculate likelihood of survival (SRR): SRR cell =A cell /(A cell +D cell ), where A cell = number discharged alive in cell & D cell =number who died in the hospital in cell. 4) Rank into levels from likely survivable to virtually unsurvivable

OH9900 DRAFT-Survival risk ratios based on US Hospital Discharge Survey-DRAFT

Limitations of methodology Deaths occurring outside hospital < 65% do not die in hospital in US Percent varies by cause, intent, age Multiple injury SRRs for ICD codes may be calculated using data with multiple injuries More injuries recorded in morbidity source than mortality Variation of injury severity within body region and nature combinations