Selecting a main injury from multiple causes of death: Step 1 Common Pairs

1. Selecting a main injury frommultiple causes of death: Step 1 Common Pairs Margaret Warner, Ph.D. Office of Analysis and Epidemiology ICE on Injury, Vienna, June 2004 Centers for Disease Control and Prevention National Center for Health Statistics

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

3. Information is lost when selecting • Rules can be established about priority, but what conclusions will be drawn from data? • One injury may not be more important • There may be combinations of injuries which are more deadly

4. Analyze data by pairs of injuries • To determine if certain combinations commonly occur together (e.g. head and thorax injuries) • If yes, • Could a main injury be selected? • Should a single code by used to identify combination?

5. Methods • US multiple cause mortality data 2001 • Injury as underlying cause of death • More than one ICD-10 S or T code • Examined unique pairs – • Two nature of injury codes were treated as a unique pair regardless of the order in data • Stratified by the number of injuries per death

6. More than one injury • In US in 2001, 157,078 deaths with external underlying cause • Range (0-15 injuries listed, possible 20) • 1 injury listed 65% of deaths • 2 injuries 22% • 3 injuries 8% • 4 -15 injuries 4%

7. Common pairs • TRUE !!!! • Certain injury pairs account for high proportion of deaths with two or more injuries listed

8. 2 injuries listed on death certificate • 35,000 deaths with 3,500 unique pairs • 18,500 deaths with 55 unique pairs • 55 pairs are … • observed 100 times or more • account for 54% of deaths with 2 injuries listed

9. Results Most frequent pair – occurs 3,327 times • S06.9 (Intracranial injury, unspecified) and S09.9 (Unspecified injury of the head) Second most frequent – occurs 2,671 times • S09.9 (Open wound of head, part unspecified) and S29.9 (Unspecified injury of the thorax)

10. Review of pairs We choose to review pairs based on … • Frequency with which pair observed • If the pair included a • Superficial injury • Unspecified

11. Preliminary conclusion • Certain injury pairs account for high proportion of deaths with two or more injuries listed • Some cases not clear choice -- some codes for multiple injuries may be used or added • Computer algorithms easily developed for many multiple injury deaths

12. Next steps • External cause of death should be considered if indicates something about nature • e.g. Poisonings, fire/flame, drowning, suffocation • Location on death certificate – Part’s I & II • Unspecifieds – more specific preferred • International replication of pairs!!!!!