 
|
|
|
||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
|
||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Journal of the New Zealand Medical Association,
11-June-2010, Vol 123 No 1316
|
||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
|
Preventability of pre-hospital trauma deaths in
southern New Zealand
James A Falconer
Trauma is the leading cause of death in New Zealand from age
1 through to 34 years, the third most common cause of death from age 35 to 54,
and overall the fourth most common cause of death in all age
groups.1
In 2004 there were 1723 trauma-related deaths in New
Zealand, of which 628 were in the 0 to 34 age range. With the exclusion of
pregnancy, trauma is the leading cause of hospitalisation from age 5 to 45
years.1 Despite the significant impact on the
health system and wider society, there have been no studies of the
preventability of trauma deaths in New Zealand.
A preventable death has been previously defined as “a
fatal outcome occurring in patients with survivable
injuries”.2 However the preventability of
trauma deaths is more difficult to quantify, and the published percentage of
those deemed preventable varies widely, anything from
2-39%.3,4 Therefore to define the degree of
preventability for this study the ISS groupings derived by Sampalis et
al2 have been used, these groupings have
previously been used by several other studies.
Studies on the preventability of trauma deaths have been
undertaken elsewhere; however New Zealand is unique in many regards, certainly
culturally and geographically. However, perhaps the biggest difference is New
Zealand’s relatively low population density of 15 people per square km,
similar to Norway and Finland but significantly less than the OECD average of 33
people per square km.5 This low population
density is even more pronounced in the southern regions, where expert medical
personnel and care can often be several hours’ road travel away.
This study was done in an attempt to determine if there was
excess pre-hospital trauma mortality in the study region. A determination could
then be made regarding further research into the component aspects of any excess
trauma, and possible preventive strategies.
MethodsAfter approval from the Lower South Regional Ethics
Committee, the names and identifiers of all people who died of an external cause
in the Otago and Southland regions (as defined by the New Zealand Local
Government Act 2002 No846) from the year 2000
to 2004 were obtained from the New Zealand Health Information Service (NZHIS). A
similar dataset was obtained from the Accident Compensation Corporation (ACC),
New Zealand’s national no-fault personal insurer, after approval from
ACC’s own ethics committee.
The two datasets were required as the NZHIS data is
based on where the patient was domiciled at time of death: therefore those that
died in the study regions but were not domiciled there were missed. ACC data is
based on location of death; however their database is not as inclusive as that
of the NZHIS.
The two datasets were then cross-matched, and all
non-trauma deaths (e.g. medical causes, suicide, drowning) and deaths outside
the study area excluded. The resultant dataset was then sent to the Department
of Justice, Coronial Service to ascertain if a post-mortem had been performed.
Those patients who had not had a post-mortem were then excluded, as were those
from early 2000 whose post-mortems had been archived and could not be obtained
within the study budget. The post-mortems for the remaining patients were
obtained from the Department of Justice, Coronial Service. Each post-mortem was
reviewed and scored according to the AIS 2005.7
The AIS is an anatomically-based scoring system, which
classifies the most severe injury for each of six body regions (head/neck, face,
chest, abdomen, extremities and external) by increasing severity from 1 to 6. An
AIS score of 1 represents an injury such as an abrasion whereas an AIS score of
6 is a non-survivable injury. The ISS is calculated from the sum of the square
of the three most severely injured body regions per patient and provides a
summary score with a range from 3 to75. An AIS score of 6 in any single body
region is automatically scored as a maximal ISS of 75.
All data collection and scoring was carried out by the
author to prevent any inter-observer variation, and the scores were then checked
by a dedicated trauma co-ordinator. Any discrepancy between scores was then
discussed with a final score being arrived at by consensus agreement.
The ISS was used to determine the preventability of the
trauma deaths as there was no available physiological data, and it has been
previously demonstrated that ISS has “validity comparable to that of a
chart review by a committee of experts”.2
Cases were classified as survivable (9-24), potentially survivable (25-49) and
non-survivable (>49) based on the ISS groupings of Sampalis et
al.2
ResultsA total list of 362 patients was initially sent to the
Department of Justice. No post-mortems had been done on 72 (20%) patients, a
decision left to the discretion of the Coroner involved on a case-by-case basis.
A further 45 (12%) had post-mortems that had been done in early 2000 that had
subsequently been archived.
Post-mortems were obtained on 245 patients and subsequently
54 (15%) patients were excluded as they either: died in hospital, out of the
study area, from suicide or non-trauma related causes. The remaining 191
post-mortems became the study dataset. These were scored according to the AIS
2005 with derivation of an ISS. This revealed 19 (10%) had scores that suggested
that they had survivable injuries, 66 (35%) had scores suggestive of potentially
survivable injuries and 106 (55%) had non-survivable scores. Of the 106 with
non-survivable scores, 90 actually had a maximal ISS of 75.
The pattern of injuries in the different regions scored by
the AIS 2005 is illustrated in Table 1. The head/neck and chest regions were
most frequently the areas with the highest single AIS scores, and combined
accounted for 74% of all the study patients. The head/neck region had the single
largest number of AIS 6 scores, which denotes a non-survivable injury. The 16
patients (8%) who had an external AIS score of 6 were motor vehicle accidents
with secondary drowning or incineration. In some patients two or even three
regions had equally high AIS scores.
Table 1. Highest
AIS† score by anatomical
region
†Abbreviated
Injury Scale.
The multiplicity of injuries in the study population is
illustrated in Table 2. Only those regions with AIS scores of two or greater are
included.
Table 2. Number of regions with AIS†
Score ≥2 per post-mortem
†Abbreviated
Injury Scale.
The causes of death are shown in Figure 1. The predominant
cause of death in this study was from motor vehicle accidents (MVAs), with falls
from a height the next most common. The falls were commonly leisure-related and
reflects the study area’s rugged geography, with many of them
mountaineering in nature. The mountainous nature of the region was also
reflected in the deaths attributable to light aircraft accidents with 11 deaths
from just 6 accidents. Five of these deaths arose from a single scenic flight
aircraft accident.
Figure 1. Cause of death
 MVA=motor vehicle accident.
Demographic breakdown of the study population is shown in
Figure 2. Fifty-one percent of the study population were aged 35 years or
younger. Males outnumbered females at a ratio of 2.4:1, and accounted for 135
(71%) of the total study population. There was also a preponderance of young
males, with 74% of those aged between 16–45 years being male.
Figure 2. Trauma deaths by age
 These results are similar to those obtained in studies
undertaken in Australia8
and Sweden,9
all of which were attempting to determine the preventability of trauma death
using AIS and ISS. However the Australian and Swedish studies only looked at
motor vehicle accidents, therefore to aid comparison between similar study
populations the motor vehicle accident subset from this study has been graphed
separately from that of ‘all trauma’ which includes this subset as
part of the total study population. The 95% confidence intervals for all of
these studies have been graphed (Figure 3) and illustrate the very similar
results.
Figure 3. 95% confidence intervals for
comparative studies
 DiscussionTrauma is a significant cause of death in New Zealand. This
is illustrated by data from the Injury Prevention Research Unit at Otago
University in Dunedin,1 and supported by the
findings of this study where the majority (51%) of the study population were
aged less than 35 years, and 71% were male. These results illustrate the
significant cost of this disease to the New Zealand Health system, and
underscore the impact it has on the wider New Zealand society.
The preventability of trauma deaths is difficult to
quantify, and there are widely divergent figures quoted in the literature
(2–39%).3,4 This variability is likely
multifactorial with possible variables including: geography, demographics,
methodologies, trauma systems and injury patterns. This is all complicated by
the fact that what may be medically preventable in an ideal situation, may
actually be non-preventable in a ‘real world’ scenario, where
constraints such as physical isolation, availability of limited resources and
prevailing weather all impact on outcomes.
Yet the results of this study are very similar to other
studies of a similar nature done in Australia8
and Sweden;9 despite the obvious geographical
and population differences. The ranges for each category from all three studies
being: survivable (ISS 9–24) 5–12%, potentially survivable (ISS
25–49) 30–35% and non-survivable (ISS >50) 55–65%.
However, of note is that the
Australian8 and
Swedish9 studies only related to motor vehicle
accidents, whereas this study was trauma deaths of all causes. However 70% of
trauma deaths in this study were also as the result of a motor vehicle accident
and if this subset is extracted, then an even tighter correlation to the
Australian8 and
Swedish9 studies is obtained, with ranges for
each category in this subset being: survivable (ISS 9-24) 5–12%,
potentially survivable (ISS 25-49) 30-32% and non-survivable (ISS >50)
57–65%. This tight correlation of ranges for each category is reflected in
the consistency of the ranges for the 95% confidence intervals between the
studies.
With regard to motor vehicle accidents, New Zealand as with
other OECD countries has had a declining mortality for many years, this is a
reflection of many things including: improved vehicle safety, public education
(e.g. seatbelts/alcohol) and hazard mitigation works on dangerous stretches of
road. However when analysis was attempted to see if this declining overall
mortality was reflected in this studies population, the results did not reach
statistical significance in the relatively short period of this study.
The majority of the study population suffered significant
(AIS≥2) injuries to multiple regions, as defined by the AIS 2005 scoring
system, with 76% injured in two regions and 51% in three or more.
Not surprisingly the head/neck and chest were the most
common sites of fatal injury accounting for 74% of the total fatalities, and the
head/neck was the single most lethally (AIS score 6) injured area (21%). This
multiplicity and pattern of injuries further supports the suggestion, based on
the injury severity scores, that the majority of pre-hospital trauma deaths in
this study are not survivable.
Given that the majority of patients in this study had
non-survivable injuries, then there is significant justification for continuing
preventative measures such as improved road configuration, driver/pilot
education and also general public education with regard to simple first aid and
injury prevention. However given the marked number of young people killed in
motor vehicle accidents combined with New Zealand’s relatively low driver
licensing age (15 years as compared to other OECD countries which are on average
17-18 years), then consideration should be given to modification and improved
young driver licensing and education.
However in this study there are still a significant
proportion of patients who had survivable or potentially survivable injuries,
who died. The cause for this is likely to be multifactorial and may reflect
retrieval times, time delay until victim found, experience of initial attending
medical staff, causation of injury, or other as yet undefined causes. This area
is one which requires further detailed study with the prospect that potentially
remedial causes of preventable deaths may be identified and subsequently
ameliorated.
New Zealand still lacks a national trauma database,
something which has been recommended and promoted both by clinicians and health
officials for at least the last decade. If implemented a national trauma
database would allow “quality assessment, standardisation and coordination
of care”11, and therefore potentially
lead to significant improvements in the provision of trauma care in New Zealand.
The benefits of a trauma system are perhaps best illustrated
by the continued decline in mortality in the state of Victoria, (Australia)
after the implementation of the Victorian State Trauma
Registry12 in 2001.
There are several factors that limited this study. The
retrospective nature of this study and the fact that it is limited to
post-mortem reports without any access to data that would allow assessment of
the patient’s physiological state. There was also no access to the
patients past medical history, Police or ambulance reports.
As the study data was derived solely from post-mortem
reports it was unable to be ascertained whether the patient was dead at the
scene, or died in transit to hospital. This would have been extremely useful
information to extract, as it would then allow a much more accurate assessment
of the practical preventability of pre-hospital trauma deaths. This is important
as with New Zealand’s rugged and sparsely populated geography then many of
these patients were possibly not found for sometime after their accidents.
There are several well recognised limitations when
classifying injuries according to the AIS and ISS scoring systems. These are
that:
ConclusionThe Otago and Southland regions of New Zealand have a
significant trauma burden, primarily from motor vehicle accidents and involving
young people. Falls, aircraft accidents and interpersonal violence also cause
significant mortality.
The majority of all trauma patients in this study suffered
non-survivable injuries, similar to comparable international studies. However,
there are still a significant number who suffered potentially survivable and
survivable injuries, who died. Therefore while there needs to be attention to
primarily preventing these accidents, there still needs to be further analysis
of those who die of potentially survivable or survivable injuries.
This analysis needs to be undertaken in an attempt to
identify remedial causes of death and consequently potentially avert future
unnecessary loss of life.
Funding: We thank
Emergency Care Co-ordination Team (ECCT), Otago District Health Board:
Provision of funding for copies of post-mortem reports from the New Zealand
Department of Justice, Coronial Service.
Author information: James A Falconer,
Registrar, Emergency Department, The Canberra Hospital, Canberra, ACT,
Australia
Acknowledgements: I thank
Associate Professor D Richardson (NRMA-ACT Road Safety Trust Chair of
Road Trauma & Emergency Medicine, Canberra Clinical School, The Canberra
Hospital) for his reviews and advice on the preparation of this paper; Rebekah
Ogilvie (Trauma Coordinator, Shock Trauma Service, The Canberra Hospital) for
her time and effort in reviewing the scoring of the post-mortems; and Dr Matthew
Ryan (Staff Specialist Emergency Medicine, Nambour Hospital, Queensland) for
reconfiguring his study data to allow a direct comparison of survivability with
the groupings used in this study.
Correspondence: Dr James A Falconer,
Registrar, Emergency Department, The Canberra Hospital, PO Box 11, Woden, ACT
2606, Australia. Email: falconer386@yahoo.co.nz
References:
|
|
||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| | Current
issue | Search journal |
Archived issues | Classifieds
| Hotline (free ads) Subscribe | Contribute | Advertise | Contact Us | Copyright | Other Journals |
|