# Presentation: 792447

## Indicators of Injury Incidence:Probability of Admission to Hospital

- Colin Cryer
*Injury Prevention Research Unit, Univ. Of Otago NZ*
*Presented at the ICE on Injury Statistics Meeting, 7-8 September 2006, Washington DC*

## Background

- Non-fatal injury indicators
- Data sources include:
- Hospital admission / discharges / separations
- Should draw attention to ‘important’ injury as judged by their resulting in:
- Threat-to-life
- Disability / threat-of disability
- Reduced quality of life
- Significant cost

- Colin Cryer, IPRU, Univ of Otago, NZ

- 7 September 2006

## Slide 3

- Colin Cryer, IPRU, Univ of Otago, NZ

- 7 September 2006

## Serious Non-fatal Injury Definition

- Hospitalised cases with ICISS*_<_0.941
- Set so that capture injury that are judged to have a high probability of admission
- Represents about 15% of all discharges from hospital for injury.
- Includes the majority of the following injuries:
- Fractured neck of femur
- Intracranial injury (excluding concussion only)
- Injuries to nerves and spinal cord at neck level
- Multiple fracture of the ribs
- Asphyxia etc.

- *International Classification of Diseases-based Injury Severity Score (based on ICD-10-AM)

- Colin Cryer, IPRU, Univ of Otago, NZ

- 7 September 2006

## Serious injury definition – validity

- Our experience is that cannot use hospital discharges to produce valid indicators without some pre-processing
- (need to control the effect of extraneous factors on admissions to hospital).
- If you do not, indicators can show potentially misleading trends
- Biases can be minimised by using a severity threshold – **assumed** to capture only injury with a high probability of admission
-       high face validity
- To have full confidence we need to test this assumption

- Colin Cryer, IPRU, Univ of Otago, NZ

- 7 September 2006

## Aims

- Primary
- To empirically investigate whether diagnoses captured using ICISS_<_0.941 have a high probability of admission
- Secondary
- To identify sentinel ICD diagnoses that have a high probability of admission

- Colin Cryer, IPRU, Univ of Otago, NZ

- 7 September 2006

## Possible outcomes

- Confirmation of the validity of the NZ indicators.
- A change to the severity threshold that define the NZIPS serious injury indicators - to ensure validity of the indicators.
- The identification of valid indicators that include lower severity injuries than the current NZ indicators.
- Abandonment of the NZIPS / ICISS-based serious injury indicators, and substitution with indicators based on a basket of sentinel injuries approach.
- A combination of these.

- Colin Cryer, IPRU, Univ of Otago, NZ

- 7 September 2006

## Proposed approach

- Sources of data: ED
- Operational definition of injury – to be agreed
- Minimum data required
- Diagnosis (ICD)
- Disposal (whether or not admitted)
- Estimate
- Diagnosis-specific admission fractions with 95% CIs

- Colin Cryer, IPRU, Univ of Otago, NZ

- 7 September 2006

## Issues

- Operational definition of injury
- Diagnosis
- Coding frames (ICD-10-AM, ICD-10, ICD-9-CM, etc.)
- Restrictive or inclusive
- Accuracy of coding
- Who codes
- Correspondence between ED and inpatient diagnoses
- Admission fractions
- Stability
- Dependency on
- Demography (eg. older people), comorbidity, circmstances
- What approach to estimation when:
- Multiple diagnoses
- Multiple attendances for same injuries
- Cases died before arrival or in ED (before admission)

- Colin Cryer, IPRU, Univ of Otago, NZ

- 7 September 2006

## Sources of data

- Potential sources identified to date:
- Australia
- Canada
- Denmark
- Greece
- Italy
- US
- Others?

- Colin Cryer, IPRU, Univ of Otago, NZ

- 7 September 2006

## What now?

- Description of potential sources of ED data
- Coding frame used
- Who codes the data
- Any information on accuracy
- Whether linked to inpatient data.
- Presentation of the issues
- Open discussion of the proposal, data sources, issues.

- Colin Cryer, IPRU, Univ of Otago, NZ

- 7 September 2006