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AIHW National Injury Surveillance UnitResearch Centre for Injury Studies
Flinders University - Adelaide - South Australia
Injury indicators: purposes, progress, prognosis
James Harrison
AIHW National Injury Surveillance Unit
Research Centre for Injury Studies, Flinders University
Overview
• Injury indicators– Purposes: Why have indicators?– Principles: Concepts, definitions & standards– Progress: Where are we up to?– Problems: Constraints– Prognosis: Next steps…
AIHW National Injury Surveillance Unit
Research Centre for Injury Studies, Flinders University
Purposes: Why have indicators?
Information to support injury prevention & control
• Support planning and policy-making
• Guide targeting and priority-setting
by• Measuring and monitoring injury, its consequences,
injury risk-factors and exposure to them
• (Contributing to) evaluation of interventions
AIHW National Injury Surveillance Unit
Research Centre for Injury Studies, Flinders University
Operator
Steam-
engine
Pressure-
time
indicator
Control
valves
Purposes: Origin of indicators
AIHW National Injury Surveillance Unit
Research Centre for Injury Studies, Flinders University
Injury
prevention
practitioners
Injury
prevention
program
Injury
indicator
Start or alter
prevention
program
Purposes: Origin of indicators
AIHW National Injury Surveillance Unit
Research Centre for Injury Studies, Flinders University
What to indicate?
Steam-engine– Risk of explosion
– Efficiency
– Effect of altered settings
Injury prevention– Burden of injury
– Risk exposure
– Effect of intervention
Things worth knowing
…especially if not directly observable
AIHW National Injury Surveillance Unit
Research Centre for Injury Studies, Flinders University
How to indicate it?
Steam-engine– Pressure-time relationship
Injury prevention– Injury incidence
– Prevalence of risk exposure
– Reach of an intervention
A. Identify and specify another thing, which: 1. Can be measured
2. Varies with the ‘thing worth knowing’
B. Make a device / information system able to provide measured values of A.
Steam-engine indicator Injury indicator
AIHW National Injury Surveillance Unit
Research Centre for Injury Studies, Flinders University
What is a good indicator?
• Steam-engine indicator– Varies predictably with time-
pressure– Not much influenced by
other things– Sensitive enough to show
important changes – Timely enough to allow good
control of engine
• Injury prevention indicator– Varies predictably with injury
occurrence– Not much influenced by other
things– Sensitive enough to show
important changes– Timely enough to allow effective
response to findings– Well-defined– Comparable (esp. over time)
One with attributes suitable for its purpose
AIHW National Injury Surveillance Unit
Research Centre for Injury Studies, Flinders University
What is a good indicator?
IInformation objective Assessment as topic for indicator
Trends in total burden of injury
• Broad scope is appealing
• Lack information for reliable measurement, especially over time
Trends in incidence of fatal and severe injury
• Narrower scope: may not be a reliable guide to (eg) trends in burden of total
• Measurement is feasible
AIHW National Injury Surveillance Unit
Research Centre for Injury Studies, Flinders University
Principles: concepts, definitions, standardsIndicators require data
• Necessary but not sufficient• Must be COMPARABLE
Foundations for comparability• Clear meaning for key concepts: eg. ‘injury’, ‘severity’, ‘outcome’ • Classifications
– eg. ICD-10, ICD-10-AM, ICECI• Operational definitions
– eg. STIPDA Consensus Recommendations for using hospital discharge data for Injury Surveillance
• Reporting standards – eg. Recommended Framework for reporting injury mortality data
• Derived measures – eg. ICISS severity, remoteness, Socio-Economic Status
• Institutional arrangements – eg. WHO-FIC, Injury ICE, STIPDA
AIHW National Injury Surveillance Unit
Research Centre for Injury Studies, Flinders University
Injury outcome indicators
• Consensus criteria (ICE on Injury Statistics)
– Define in terms of anatomical/physiological damage
– Serious injury
– Case ascertainment independent of extraneous factors
– Representative of target population
– Available data
– Well-documented (definitions, methods, etc)(Cryer, Langley, et al
2005)
AIHW National Injury Surveillance Unit
Research Centre for Injury Studies, Flinders University
Progress: Where are we up to?
Australia as an example
Focus on trends in severe & fatal injury• c. 10 years at national level
• Deaths and hospitalised injury
• Onion metaphor: layers of work (iterative)– Getting, understanding, ‘cleaning’ & documenting data
– Scope: defining and operationalising definition of ‘injury’
– Methods to avoid multiple counting
– Methods to assess & control changing sample fraction
AIHW National Injury Surveillance Unit
Research Centre for Injury Studies, Flinders University
Full specification can be complex
Fatal cases Deaths occurring in Australia during the year from 1 July 2002 and registered within six months of the end of that year where any Multiple Cause of Death code is in the range S00-T75 or T79 and Underlying Cause of Death is in the range V01-V98. If Underlying Cause is not an External Cause, then include if (any) (first-mentioned external cause) Multiple Cause of Death code is in the range V01-V98 and the person was a resident of Australia.
Non-fatal high-threat to life cases
Episodes of admitted patient (acute) care in any acute-care hospital that (commenced) (ended) during the year from 1 July 2002 where (principal) (any) diagnosis code is in the range S00-T75 or T79 and (any) (the corresponding) external cause code is in the range V01-V75 or V79 and the person was not admitted following transfer from an acute care hospital and the (all injuries multiplicative) (worst injury) ICISS severity score is < 0.941 and the person is recorded as residing in Australia and the episode ended with the patient alive.
Population Estimated resident population at 31 December 2000.
Rates Numerator values are sums of fatal cases and the non-fatal instances of types of injury that pose high threat to life. Rates are adjusted for age by the direct method using the Australian population in 2001 as the reference (and stratified or adjusted for remoteness of place of residence and Indigenous status).
Incident fatal and severe injury due to Transport
AIHW National Injury Surveillance Unit
Research Centre for Injury Studies, Flinders University
…but different methods can give very different values
‘Underlying cause of death’ coded to Accidental Falls (W00-W79) 629
‘Underlying cause of death’ coded to Unspecified cause (X59)
with a fracture as an ‘additional cause’ Mostly falls by people aged 75 and older at death
Cause unspecified mainly because ABS does not seek one at this age
888
‘Underlying cause of death’ coded to Natural cause (i.e. not injury)
with additional cause codes for injury condition(s)
and for fall as external cause of injury ‘Underlying cause’ is coded to circulatory disease in 49%
Small differences in wording on death certificates affect whether coded as injury deaths.
1,518
How many deaths following injury due to a fall are recognised as such?
Of deaths registered in Australia in 2002:
AIHW National Injury Surveillance Unit
Research Centre for Injury Studies, Flinders University
Injury all ages (NHPA indicator 1.2) Australia 1993-94 to 2002-03
0
200
400
600
800
1,000
1,200
1,400
1993
-94
1994
-95
1995
-96
1996
-97
1997
-98
1998
-99
1999
-00
2000
-01
2001
-02
2002
-03
Year of separation
case
s/10
0,00
0 po
p
all separations
Excl transfers from acute hospitals
Excl transfers to acute hospitals
…even if differences are subtle
Age-adjusted rates
AIHW National Injury Surveillance Unit
Research Centre for Injury Studies, Flinders University
Falls ages 75+ (NHPA indicator 1.2) Australia 1993-94 to 2002-03
0
500
1,000
1,500
2,000
2,500
3,000
3,500
4,000
1993
-94
1994
-95
1995
-96
1996
-97
1997
-98
1998
-99
1999
-00
2000
-01
2001
-02
2002
-03
Year of separation
case
s/10
0,00
0 po
p
all separations
Excl transfers from acute hospitals
Excl transfers to acute hospitals
Has the age-adjusted rate risen?
Age-adjusted rates
AIHW National Injury Surveillance Unit
Research Centre for Injury Studies, Flinders University
Aspects of burden of hospitalised injury
0
10,000
20,000
30,000
40,000
50,000
60,000
70,00019
95-9
6
1996
-97
1997
-98
1998
-99
1999
-00
2000
-01
2001
-02
2002
-03
Cas
es
0
500
1,000
1,500
2,000
2,500
Cas
es/1
00,0
00 p
opul
atio
n
Cases
Crude rate
Adj. Rate
Hospitalisation due to Accidental Falls ages 65 and older, Australia 1995-6 to 2002-3
AIHW National Injury Surveillance Unit
Research Centre for Injury Studies, Flinders University
Aspects of burden of hospitalised injuryHospitalisation due to Accidental Falls ages 65 and older, Australia 1995-6 to 2002-3
0
200,000
400,000
600,000
800,000
1,000,000
1,200,00019
95-9
6
1996
-97
1997
-98
1998
-99
1999
-00
2000
-01
2001
-02
2002
-03
Bed
-day
s
No injury Dx; Fall ext. cause
Other (AdDx injury)
Rehabilitation (AdDx injury)
Injury (PrDx)
AIHW National Injury Surveillance Unit
Research Centre for Injury Studies, Flinders University
Problems: Constraints
• Data quality (incl timeliness)– Variation in % of cases incident in population admitted to hospital?
(Especially for low severity injuries?)• Difficulty and costliness of validation studies
– special studies; WA linked data• Data (mostly) not person-linked
– >episode (ie record) / incident case of admitted injury: tricky to allow for this source of multiple counting of cases
– hospital data and deaths data: do in-hospital ‘injury deaths’ appear as ‘injury deaths’ in national deaths data collection?
• Access (administrative issues, privacy)• Complexity (esp for ‘clever data cleaning’)• Classification
– Australian clinical modification of ICD-10 (ICD-10-AM)– revisions (each 2y) allow useful enhancement of Injury & External Cause codes– … but (so far) the revised codes are not used for routine mortality data
AIHW National Injury Surveillance Unit
Research Centre for Injury Studies, Flinders University
Signal & noise: example 1Nature Injury (principal diagnosis) All 1993-94 to 2002-03
75 years and older
0.0
1000.0
2000.0
3000.0
4000.0
5000.0
6000.0
1993
-94
1994
-95
1995
-96
1996
-97
1997
-98
1998
-99
1999
-00
2000
-01
2001
-02
2002
-03
rate
(/1
00,0
00 p
op
)
1.0
10.0
rati
o (
seri
es 1
:2)
Australia separations
Australia cases (est.)
sub-area A cases (est.)
ratio [1:2]
Age-adjusted rates
AIHW National Injury Surveillance Unit
Research Centre for Injury Studies, Flinders University
Signal & noise: example 2M echanism Injury (principal diagnosis) M otorcyclist 1993-94 to 2002-03 Australia 0-4 years and older (cases (est.))
0.0
5.0
10.0
15.0
20.0
25.0
30.0
35.0
40.0
1993
-94
1994
-95
1995
-96
1996
-97
1997
-98
1998
-99
1999
-00
2000
-01
2001
-02
2002
-03
rate
(/1
00,0
00 p
op
)
NSW, Vic, ACT & NT
Qld, SA, WA & Tas
Age-adjusted rates
AIHW National Injury Surveillance Unit
Research Centre for Injury Studies, Flinders University
Prognosis: Next steps…
• What?– Broader scope: of burden (eg rehab, late care)– Broader scope: of severity (eg ED)– Broader scope: exposures as well as outcomes– Prediction of non-fatal outcomes– Better denominators– Shorter lag (+/- model-based prediction)
• How?– Standards (more, better, more widely used)– Linkage– Incremental system improvements
AIHW National Injury Surveillance Unit
Research Centre for Injury Studies, Flinders University
Summary– Purposes: Why have indicators?
• To estimate trends (and differences) in important phenomena, which are not directly observable
– Principles: concepts, definitions & standards• The technical foundation; essential for comparability
– Progress: • Coming together… quite good trends data for serious injury
– Problems:• Constraints are real, tricky but generally manageable
– Prognosis:• Exciting times (nb linkage)• Grail: ICISS-like measure(s) for important non-fatal
outcomes
AIHW National Injury Surveillance Unit
Research Centre for Injury Studies, Flinders University
AIHW National Injury Surveillance Unit
Research Centre for Injury Studies, Flinders University
After dinner…?
AIHW National Injury Surveillance Unit
Research Centre for Injury Studies, Flinders University
AIHW National Injury Surveillance Unit
Research Centre for Injury Studies, Flinders University
Understanding the issue
• Demographics of injured people
• Types of injury
• Severity and outcomes
• Risk factors and exposure
• Effectiveness and use of interventions
AIHW National Injury Surveillance Unit
Research Centre for Injury Studies, Flinders University
Targeting and priority-setting
• (potential) topics for indicators– Frequency– Risk– Burden– Potential for improvement
AIHW National Injury Surveillance Unit
Research Centre for Injury Studies, Flinders University
Approaches• Opportunistic
• Using existing data and other resources
• Making the most of them for injury surveillance– Understanding, creative use, incremental enhancements
• Purposive / strategic• Data sources and other components of injury
surveillance developed specially to serve this purpose
AIHW National Injury Surveillance Unit
Research Centre for Injury Studies, Flinders University
Approaches
Opportunistic Purposive
Case data sources ABS mortality
NHMD
VEMD NCIS
QISU-ED
Trauma registers ASCIR
Classifications ICD (‘vanilla’) ICD-10-AM
ICECI
Concepts, definitions ICD, NHDD ICE on Injury Statistics
AIHW National Injury Surveillance Unit
Research Centre for Injury Studies, Flinders University
StatusFatal and serious injury
• Hospital separations and deaths• Cross-sectional and trends • Better understanding of data -> better use• Good useable system
– Will benefit from further validation, etc
• Basis for – Reporting of indicators– Numerous analyses of specific topics – Use with cost-models for good injury costings– Use in GBD models– …
AIHW National Injury Surveillance Unit
Research Centre for Injury Studies, Flinders University
StatusOccurrence
– Incident fatal & severe injury– Characterised in terms of ICD-10-AM, LoS, threat to life,
demographic characteristics etc.– Period: deaths - many years, hospitalised – c. 10 years– 1-2 year lag (2-3 y latency for system changes)
Risks and burden– Population-based rates
• Age/sex/remoteness/SEIFA/CoB/etc (+/- indigenous status)
– Other denominators• Potentially diverse; patchy availability
– Other units• Cost, DALYs
AIHW National Injury Surveillance Unit
Research Centre for Injury Studies, Flinders University
StatusChange in occurrence (trends)
• Challenges:– Hospital data
• (largely) not person-linked: multiple counting
• differences in admission/recording: variable sample
• variations in data quality
– Deaths
• ‘Injury death’ vs UCoD External Cause
• changes in coding some types of death
• Manageablewith care …
AIHW National Injury Surveillance Unit
Research Centre for Injury Studies, Flinders University
Future?
• Technical developments
• Maintenance
• Operational links
AIHW National Injury Surveillance Unit
Research Centre for Injury Studies, Flinders University
Future? Technical developments1. Standards
For comparable & meaningful data…
2. OutcomesMeasure & describe outcomes of injury (in addition to death)
3. LinkageIllness service utilisation data, case data/event data, case
data/population data
4. Denominators / exposure dataBetter population data (nb Indigenous); other denominators
5. Knowledge, attitudes, behaviour…of Australians concerning injury, injury prevention, interventions
AIHW National Injury Surveillance Unit
Research Centre for Injury Studies, Flinders University
1. StandardsNeeded for comparable & meaningful data
– Including:• Operational definition(s) of ‘injury’
– For deaths, hospital data, other sources
– Australia: Technical Review & Revision of injury indicators
– International: ICE on Injury Statistics; ICECI
• Classifications– ICD-10, ICD-10-AM, ICECI
• Data standards / minimum data sets– NDS-IS, NCIS data set
• Survey questions
– Opportunities:• Consideration/contribution to/adoption of international standards
• Further development & updating of Australian standards
AIHW National Injury Surveillance Unit
Research Centre for Injury Studies, Flinders University
2. Outcomes
Measure & describe outcomes of injury– Overview:
• Fairly good methods to measure threat to life of injury– AIS & derivatives, GCS etc, ICISS
• Much of burden of injury is due to consequences other than death
• Methods to measure ‘threat to health’ of injury are immature
• Progress is likely to require large and expensive prospective studies
– Opportunities:• Collaborative project(s), national or international
AIHW National Injury Surveillance Unit
Research Centre for Injury Studies, Flinders University
3. Linkage
Potential for more information from existing data– May include:
• Person-based linkage of illness service utilisation data, etc
• Linking case data to event data (eg hospital / crash)
• Linking case data to population data (eg enhanced census)
• Linking special injury register data to any of these
– Opportunities:• Collaborative projects using WA Linked Health Data
• Advocacy for similar capabilities elsewhere
• National developments
AIHW National Injury Surveillance Unit
Research Centre for Injury Studies, Flinders University
4. Denominators/exposure dataPotential for more information from existing case data
– Types of denominators:• Better population data
– nb reliable estimates of Indigenous population
• Injury risk factor / exposure data– Eg. more specific sports-participation data, alcohol use data,
travel/vehicle use data
• Injury protective factor / intervention – Eg participation by older persons in specified exercise activities
– Opportunities: • Diverse
AIHW National Injury Surveillance Unit
Research Centre for Injury Studies, Flinders University
5. Knowledge, attitudes, behaviourKnowledge, attitudes, behaviour
• …of Australians concerning injury, injury prevention, interventions
– Themes:• Knowledge
– What is the extent, distribution and reliability of knowledge about injury occurrence, consequences and potential for prevention.
• Attitudes– What is the direction (positive or negative) and strength of attitudes
towards injury prevention generally and to specific interventions.
• Behaviour – What are the population patterns of certain behaviours that increase or
decrease injury risk
– Opportunities: • CATI surveys
AIHW National Injury Surveillance Unit
Research Centre for Injury Studies, Flinders University
Future? Maintenance– Maintain current data sources & quality
• eg loss of items from ABS mortality data
• eg signs of possible deterioration of injury coding in some hospital records
– Ensure good understanding of data • Validation studies (eg ARC project)
– Continue to tap value from existing sources• Novel analytic methods (eg ICISS)
• More efficient analysis & access (cf US WISQARS)
• Minor changes (eg ICD-10-AM biennial revisions)
AIHW National Injury Surveillance Unit
Research Centre for Injury Studies, Flinders University
Future? Operational links – Better understanding of uses and users
• Governments, researchers, industry, community– Consult, discuss, seek feedback
• Look for lessons in related activities– Other public health surveillance ane information activities– Injury surveillance elsewhere
– Close liaison with policy-makers• Individually and though national forums• Health and other sectors
– Seek two-way connection with policy• … in which surveillance information
– helps shape policy– supports its implementation and monitoring
AIHW National Injury Surveillance Unit
Research Centre for Injury Studies, Flinders University
ReviewInjury surveillance systems & information
PurposesInformation to support injury prevention & control
ApproachesOpportunistic and purposive
StatusGood system for severe and fatal injury
Future– Standards; Outcomes; Linkage; Denominators/exposure data;
Knowledge, attitudes, behaviour– Maintenance– Operational links and relationships
AIHW National Injury Surveillance Unit
Research Centre for Injury Studies, Flinders University
AIHW National Injury Surveillance Unit
Research Centre for Injury Studies, Flinders University
Why better now?• Ten year series of data
• Quality fairly good and has generally improved
• Completeness
• Similarity between jurisdictions
• Better understanding• Of data strengths and limitations
• Development of concepts and methods• Eg severity measures, injury definitions
AIHW National Injury Surveillance Unit
Research Centre for Injury Studies, Flinders University
Trends in injury incidence: issues• Records are for inpatient episodes, not
persons injured
• Proportion of incident injury cases resulting in admission might change over time.
• Identifiability of separation records as relating to an “injury” might change over time
AIHW National Injury Surveillance Unit
Research Centre for Injury Studies, Flinders University
Burden of hospitalised injury
0
10,000
20,000
30,000
40,000
50,000
60,000
70,00019
95-9
6
1996
-97
1997
-98
1998
-99
1999
-00
2000
-01
2001
-02
2002
-03
Cas
es
0
500
1,000
1,500
2,000
2,500
Cas
es/1
00,0
00 p
opul
atio
n
Cases
Crude rate
Adj. Rate
Hospitalisation due to Accidental Falls ages 65 and older, Australia 1995-6 to 2002-3
AIHW National Injury Surveillance Unit
Research Centre for Injury Studies, Flinders University
SCI: trends and prioritiesPersisting Spinal Cord Injury due to motor vehicle accidents,
ages 15y and older, Australia 1995-6 to 2003-4
0
2
4
6
8
10
1995-9
6
1996-9
7
1997-9
8
1998-9
9
1999-0
0
2000-0
1
2001-0
2
2002-0
3
2003-0
4
Year of injury
Cases/1
00,0
00 p
opula
tion
Motorcyclists
Other MVTA
M/cyclists, 15-34y
AIHW National Injury Surveillance Unit
Research Centre for Injury Studies, Flinders University
Improvements• Understanding the data
• Estimating incident cases• Comparability over time & between places• Coding validation (ARC project)• Completeness (external cause codes, activity, etc)
• New uses of the data• ICD-based severity measures
• Classification• ICD-10-AM 3rd • ICD-10-AM 5th
AIHW National Injury Surveillance Unit
Research Centre for Injury Studies, Flinders University
Classification• ICECI
• Development was prompted by dissatisfaction with ICD External Causes classification:– Lagged behind theory (eg energy transfer concept)– Technical defects (eg not multi-axial)
• Developed by international collaborative group• Challenges:
– Enable refinement– Keep current– Translation (concepts as well as language)– Minimise burden of maintenance
AIHW National Injury Surveillance Unit
Research Centre for Injury Studies, Flinders University