International Comparison International Comparison of Injury Case-Fatality of Injury Case-Fatality

Rates in the United Rates in the United States and New ZealandStates and New ZealandTed Miller, PhDTed Miller, PhDRebecca Spicer, PhD, MPHRebecca Spicer, PhD, MPHPacific Institute for Research and Pacific Institute for Research and Evaluation, Calverton, MD, USAEvaluation, Calverton, MD, USA

John Langley, PhDJohn Langley, PhDShaun StephensonShaun StephensonInjury Prevention Research Unit, Injury Prevention Research Unit, University of Otago, Dunedin, New University of Otago, Dunedin, New ZealandZealand

ObjectivesObjectives To compare injury case-fatality rates To compare injury case-fatality rates

between the United States and New between the United States and New ZealandZealand

Use the observed differences to generate Use the observed differences to generate new research questionsnew research questions

MethodsMethods DataData

New Zealand E-coded hospital discharge and New Zealand E-coded hospital discharge and mortality census data (1992-1996)mortality census data (1992-1996)

United States National Hospital Discharge United States National Hospital Discharge Survey (1996)Survey (1996) 63% of cases E-coded63% of cases E-coded E-codes for the remainder of cases modeled E-codes for the remainder of cases modeled

based on diagnosis and age group.based on diagnosis and age group. United States mortality census data (1996)United States mortality census data (1996)

Hospitalized case definition: AIS 3 to 6 only, first Hospitalized case definition: AIS 3 to 6 only, first admission, not discharged deadadmission, not discharged dead

fallmv-related

other transport

natural/env.

bicycle

poison

struck

other & unsp.

firearmburn

machinery

drown

cut/pierce

firearmmachinery

mv-related

other transport

natural/env.

bicycle

poison

struck

other & unsp.

burn

fall

drown

cut/pierce

New Zealand35,552 Cases

United States744,476 Cases

Injury Case-Fatality Injury Case-Fatality Rates (CFR)Rates (CFR)

21%

25%

19%

20%

21%

22%

23%

24%

25%

26%

United States New Zealand

Per

cant

age

Fata

l

CFR Comparison: by CFR Comparison: by CauseCause

0%

20%

40%

60%

80%

100%

120%

New Zealand

United States

CFR for Cutting/Piercing CFR for Cutting/Piercing Injuries: by IntentInjuries: by Intent

38%

19%

40%

55%

22%

7%

22%

62%

0%

10%

20%

30%

40%

50%

60%

70%

All Unintentional Assault Self-Inflicted

New Zealand

United States

CFR for Firearm Injuries: CFR for Firearm Injuries:

by Intentby Intent93%

64%

89%97%

67%

34%

56%

96%

0%

20%

40%

60%

80%

100%

120%

All Unintentional Assault Self-Inflicted

New Zealand

United States

CFR for Poisoning CFR for Poisoning Injuries:Injuries:by Intentby Intent

95%

67%

99%91% 93%

85%

100% 100%

0%

20%

40%

60%

80%

100%

120%

All Unintentional Assault Self-Inflicted

New Zealand

United States

CFR for Motor Vehicle-CFR for Motor Vehicle-Related Injuries: by Related Injuries: by

Victim TypeVictim Type

29%

45%

33%

38%

17%

22%20%

34%

0%

5%

10%

15%

20%

25%

30%

35%

40%

45%

50%

Motorcyclist Occupant Pedalcyclist Pedestrian

New Zealand

United States

ConclusionsConclusions Case-fatality rates in NZ and the US Case-fatality rates in NZ and the US

differ dramatically depending on the differ dramatically depending on the cause of the injury.cause of the injury.

Why?Why?

Possible reasons for the Possible reasons for the observed differencesobserved differences

Data collection and coding procedures?Data collection and coding procedures? Motor vehicle injuries:Motor vehicle injuries:

Road and vehicle standards?Road and vehicle standards? Helicopter transport for the severely injured?Helicopter transport for the severely injured?

Firearm injuries:Firearm injuries: Types of firearms?Types of firearms? Greater US experience treating gunshot victims?Greater US experience treating gunshot victims?

Poisoning:Poisoning: Poison treatment availability?Poison treatment availability? Types of poisons?Types of poisons?

Mechanical injury: occupational differences?Mechanical injury: occupational differences? Burn injury: Risk of house fires in the US?Burn injury: Risk of house fires in the US? Natural/environmental injury: Environment/animal Natural/environmental injury: Environment/animal

differencesdifferences

LimitationsLimitations Possible coding differences between Possible coding differences between

countriescountries Small number of cases, particularly for Small number of cases, particularly for

New ZealandNew Zealand Misclassification of causeMisclassification of cause