1. www.kent.ac.uk/chss Centre for Health Services Studies ICE on Injury Statistics Business Meeting, 6 June 2004 – Injury Indicators update Colin Cryer Senior Research Fellow

2. Centre for Health Services Studies www.kent.ac.uk/ chss 2 Activities since Paris 2003 Email to ADVICE-USERS@LISTSERV.CDC.GOVADVICE-USERS@LISTSERV.CDC.GOV Lee Annest: 2 indicator reports from CDC (USA) Yvette Holder Report: violence indicators (International) Saakje Mulder Eurocost (European) Indicators for priority setting (National) John Langley Report and paper: ICISS (Australia & New Zealand) Paper: Trends in neck of femur fracture (National) Paper: Trends in injury: service delivery effects versus real effects (National) New Zealand Injury Prevention Strategy [NZIPS] (National) Injury Outcome Indicators

3. Centre for Health Services Studies www.kent.ac.uk/ chss 3 New Zealand Injury Prevention Strategy Injury Outcome Indicators ‘All injury’ 6 priority areas Assault Workplace injury Suicide and deliberate self-harm Falls Motor vehicle traffic crashes Drowning and near-drowning Approach Identify current national indicators Identify generic fatal and serious non-fatal indicators Apply to priority areas Validate all using our ICEIInG criteria (Washington DC, 2001)

4. Centre for Health Services Studies www.kent.ac.uk/ chss 4 A tool for investigating face validity - Injury ICE, Washington 2001 Case definition The indicator should reflect the occurrence of injury satisfying some case definition of anatomical or physiological damage. Serious injury The indicator should be based on events that are associated with significantly increased risk of impairment, functional limitation, disability of death, decreased quality of life, or increased cost. Case ascertainment The probability of a case being ascertained should be independent of social, economic, and demographic factors, as well as service supply and access factors. Representativeness The indicator should be derived from data that are inclusive or representative of the target population that the indicator aims to reflect. Data availability It should be possible to use existing data systems, or it should be practical to develop new systems, to provide data for computing the indicator. Specification The indicator should be fully specified to allow calculation to be consistent at any place and at any time.

5. Centre for Health Services Studies www.kent.ac.uk/ chss 5 Generic fatal and serious non-fatal indicators Fatal (Source: National mortality data) Age-standardised mortality rate per 100,000 person years at risk. Number of injury deaths Serious non-fatal (Source: National hospital discharge data) Age-standardised serious non-fatal injury rate per 100,000 person years at risk. Number of cases of serious non-fatal injuries

6. Centre for Health Services Studies www.kent.ac.uk/ chss 6 Definition of a serious non-fatal injury ICISS < 0.941 Implies: includes cases with an estimated probability of death of 5.9% or greater High threshold Only includes cases of injury that have a very high likelihood of admission to hospital Examples: Fracture of the neck of femur Intracranial injury (excluding concussion only cases) Injuries of nerves and spinal cord at neck level

7. Centre for Health Services Studies www.kent.ac.uk/ chss 7 What is ICISS? ICD-based Injury Severity Score Threat-to-life anatomical severity of injury measure How are ICISS scores derived?: Survival probabilities calculated for every ICD-10-AM diagnosis from large data sets from which survival status is known Survival probabilities combined where multiple injuries Gives ICISS score (1 – ICISS score) = Pr (death) Note: also calculated for ICD-9-CM-A Retrospective trends based on both 9 th and 10 th revisions

8. Centre for Health Services Studies www.kent.ac.uk/ chss 8 Validity of indicators - General findings Quality of data Few publications - None recent Overseas work indicates potential problems Potential threat to validity for all indicators National indicators Fatal injury indicators – Satisfy our validation criteria Non-fatal indicators - Significant threat to validity Generic indicators Satisfy our validation criteria (Fatal & Serious non-fatal)

9. Centre for Health Services Studies www.kent.ac.uk/ chss 9 Trends in generic indicators – ‘all injury’

10. Centre for Health Services Studies www.kent.ac.uk/ chss 10 Discussion Interesting findings Expect trends for deaths and injuries of this severity to be similar Reasons for differences: Data problems? Preventive activities selectively preventing deaths but not serious injury Case fatality rate falling – ie. effect of better treatment (eg Roberts BMJ 1996) Getting more seriously injured people to hospital before they die Other? Argument for combining fatal and serious non-fatal injury to overcome these problems Net effect: no decrease?

11. www.kent.ac.uk/chss Centre for Health Services Studies www.kent.ac.uk/chss