Motor Vehicle Crashes in New Zealand 2011 - Ministry of Transport
Motor Vehicle Crashes in New Zealand 2011 - Ministry of Transport
Motor Vehicle Crashes in New Zealand 2011 - Ministry of Transport
You also want an ePaper? Increase the reach of your titles
YUMPU automatically turns print PDFs into web optimized ePapers that Google loves.
NEW ZEALAND INJURY PREVENTION STRATEGY SERIOUS INJURY OUTCOME INDICATORS 167<br />
NOTES<br />
1. The <strong>New</strong> <strong>Zealand</strong> Injury Prevention Strategy (NZIPS)<br />
The NZIPS is an expression <strong>of</strong> the government’s<br />
commitment to work<strong>in</strong>g with organisations and groups<br />
<strong>in</strong> the wider community to improve the country’s <strong>in</strong>jury<br />
prevention performance. The Strategy’s vision is “a safe<br />
<strong>New</strong> <strong>Zealand</strong>, becom<strong>in</strong>g <strong>in</strong>jury free”. (For further details<br />
see www.nzips.govt.nz.)<br />
‘<strong>Motor</strong> vehicle traffic crashes’ is one <strong>of</strong> the six priority<br />
areas identified <strong>in</strong> the strategy.<br />
2. NZIPS serious <strong>in</strong>jury <strong>in</strong>dicators<br />
Official serious <strong>in</strong>jury outcome <strong>in</strong>dicators have been<br />
developed for each <strong>of</strong> the six priority areas as the ma<strong>in</strong><br />
means <strong>of</strong> measur<strong>in</strong>g performance <strong>in</strong> reduc<strong>in</strong>g <strong>in</strong>jury.<br />
Chart books with the full set <strong>of</strong> <strong>in</strong>dicators can be found<br />
by visit<strong>in</strong>g the Statistics NZ website:<br />
www.statistics.govt.nz and search<strong>in</strong>g for NZIPS serious<br />
<strong>in</strong>jury <strong>in</strong>dicators<br />
Several <strong>of</strong> the <strong>of</strong>ficial NZIPS <strong>in</strong>dicators for motor vehicle<br />
traffic crashes are presented <strong>in</strong> this section.<br />
3. What is a serious <strong>in</strong>jury?<br />
The def<strong>in</strong>ition <strong>of</strong> serious <strong>in</strong>jury adopted for the <strong>of</strong>ficial<br />
NZIPS <strong>in</strong>dicators is: serious <strong>in</strong>juries are those that result<br />
<strong>in</strong> death or an admission to hospital that is associated<br />
with at least a 6 percent chance <strong>of</strong> death. The methods<br />
by which cases <strong>of</strong> fatal and serious non-fatal <strong>in</strong>jury are<br />
identified are described briefly <strong>in</strong> The <strong>New</strong> <strong>Zealand</strong><br />
Injury Prevention Strategy Injury Indicators: Technical<br />
Report. The technical report can be found on the<br />
Statistics NZ website.<br />
4. The graphs<br />
Time period<br />
Where possible, the period presented for serious<br />
non-fatal <strong>in</strong>juries is 1994 to 2010. For fatal <strong>in</strong>juries, the<br />
period presented is 1994 to 2008. Because many cases<br />
<strong>of</strong> <strong>in</strong>jury-related death are required to be reviewed by a<br />
Coroner, there is a time delay <strong>in</strong> the record<strong>in</strong>g <strong>of</strong> the<br />
cause <strong>of</strong> fatal <strong>in</strong>jury. Hence, 2008 is the most recent year<br />
available for the mortality data.<br />
the number <strong>of</strong> deaths and hospitalisations attributable to<br />
<strong>in</strong>jury. Readers should exercise caution if comment<strong>in</strong>g<br />
on trends that <strong>in</strong>clude <strong>in</strong>dicator values based on both<br />
ICD-9 and ICD-10 coded data. For this reason, the bars<br />
on the graphs have been shaded differently to highlight<br />
the change. Intermediate shad<strong>in</strong>g has been used for the<br />
bars for 1999 for <strong>in</strong>dicators based on hospitalisation<br />
data, because 1999 was a transitional year when both<br />
ICD-9 and ICD-10 cod<strong>in</strong>g systems were used.<br />
Basel<strong>in</strong>e<br />
The ‘basel<strong>in</strong>e’ provides a po<strong>in</strong>t from which to compare<br />
the frequencies and rates <strong>of</strong> <strong>in</strong>juries. It is the average<br />
count or rate <strong>of</strong> <strong>in</strong>jury for the three years lead<strong>in</strong>g up to<br />
the launch <strong>of</strong> NZIPS (2001-2003).<br />
Confidence <strong>in</strong>tervals<br />
Each bar on each chart has confidence <strong>in</strong>tervals shown<br />
as vertical l<strong>in</strong>es. These give an <strong>in</strong>dication <strong>of</strong> the amount<br />
<strong>of</strong> random variation associated with a s<strong>in</strong>gle year’s<br />
<strong>in</strong>dicator value. Where wide confidence <strong>in</strong>tervals are<br />
displayed, little weight should be given to the variation<br />
from one year to the next — it could be due to chance<br />
alone. When consider<strong>in</strong>g trends, observ<strong>in</strong>g the degree<br />
<strong>of</strong> overlap <strong>of</strong> confidence <strong>in</strong>tervals for <strong>in</strong>dividual bars<br />
(years) is helpful as an aid to <strong>in</strong>terpretation <strong>of</strong> trends. If<br />
confidence <strong>in</strong>tervals do not overlap the basel<strong>in</strong>e, this is<br />
<strong>in</strong>dicative <strong>of</strong> a change from basel<strong>in</strong>e that is unlikely to be<br />
due to chance alone.<br />
5. Age standardised rates<br />
Age standardised rates provide an estimate <strong>of</strong> an<br />
<strong>in</strong>dividual’s average annual risk <strong>of</strong> be<strong>in</strong>g <strong>in</strong>jured. Age<br />
standardisation is a process <strong>of</strong> adjust<strong>in</strong>g the rates <strong>of</strong><br />
<strong>in</strong>jury to account for changes <strong>in</strong> the age structure <strong>of</strong> a<br />
population over time. It allows comparison <strong>of</strong> the rates<br />
<strong>of</strong> <strong>in</strong>jury from one year to another, tak<strong>in</strong>g <strong>in</strong>to account<br />
the age<strong>in</strong>g population.<br />
Bar shad<strong>in</strong>g<br />
The cod<strong>in</strong>g scheme used for the diagnosis <strong>of</strong> <strong>in</strong>jury is<br />
the World Health Organization (WHO) International<br />
Classification <strong>of</strong> Diseases (ICD)4. Dur<strong>in</strong>g the period<br />
considered <strong>in</strong> these charts, the ICD was substantially<br />
revised, and a new version <strong>of</strong> the cod<strong>in</strong>g scheme was<br />
<strong>in</strong>troduced (from ICD-9 to ICD-10, refer Technical<br />
Report). This change has resulted <strong>in</strong> some differences <strong>in</strong>