Trauma atlas map Consumer summary Frequently asked questions

The trauma domain of the Atlas of Healthcare Variation shows variation in the provision and use of trauma services by district health board (DHB) area.

Injury is the third leading cause of health loss in children and young people, and the fifth leading cause of health loss for all age groups in New Zealand[1].

Injured patients stand the best chance of making a good recovery if the trauma care system performs well.

In June 2012 the Ministry of Health and the Accident Compensation Corporation established and jointly funded the Major Trauma National Clinical Network. This Network oversees and gives clinical leadership to major trauma services in New Zealand to help them deliver services in a planned and consistent way. The Network has developed and implemented the New Zealand Major Trauma Registry (NZMTR), a national major trauma database. 

The trauma Atlas domain presents injury indicators using data from hospital based trauma registries where they exist and the Ministry of Health’s National Collections database.

Key findings – updated January 2016 with 2012–14 data

Approximately 27,000 people were admitted to public hospitals with physical injuries each year.

People aged 65 years and over who are admitted to hospital as a result of physical injury are twice as likely to die as those aged 25–64 years.

Major trauma registry data was available for analysis from seven of the 20 district health boards (DHBs) covering 52 percent of New Zealand’s population.

Public hospitals with major trauma registers reported approximately 700 admissions for major trauma injuries each year.

No significant variations in admission or death rates were reported between DHBs.

Methods

The performance of the trauma system can be measured using information on the incidence of injury (where prevention has a role), the severity of injury, and death resulting from injury (where the process of care is important).

This Atlas domain presents six indicators for all physical injuries and major trauma injuries, including injury incidence, mortality and time from injury to treatment. The methodology is available here or on the single map.

Indicator definitions

a) Physical injury (indicators 1–3)

Physical injury includes all injuries except:

  • injuries caused by means other than energy transfer (eg, poisoning, hanging and drowning)
  • injuries that may have been caused by other disease processes such as osteoporosis or cancer
  • isolated neck of femur fractures.

Physical injury data was drawn from the National Minimum Dataset (NMDS), which is available from public hospitals for all DHBs.

b) Major trauma injury (indicators 4–6)

We defined major trauma patients according to the Abbreviated Injury Scale used at the relevant hospital[2]. For Auckland DHB and Counties Manukau Health (using AIS 1998), we used an Injury Severity Score (ISS) greater than 15. For Waikato, Bay of Plenty, Taranaki and Lakes DHBs (using AIS 2008) we used an ISS greater than 12[3]. The score correlates with mortality, morbidity and time spent in hospital after trauma.

The six DHBs with hospital trauma registries provided data for the major trauma indicators.

Key findings for each indicator

Physical injury indicators

Indicators 1–3 include all people admitted to hospital with physical injuries between 2012 and 2014.

1. Admissions due to physical injury, by DHB of domicile (NMDS), 2012–14

This indicator shows how many people from across New Zealand were admitted to hospital as a result of physical injury, according to where those people live.

The analysis for this indicator shows:

  • on average, 5.9 people/1000 population (586/100,000) were admitted to hospital each year
  • admissions for people aged 65 and over (11.3/1000 population) were more than double those for people aged 25–64 years (4.4/1000)
  • more males were admitted than females (7.1 vs 4.7/1000 population)
  • Māori (6.5/1000 population) and Pacific peoples (6.2/1000) were admitted more often than all other ethnic groups combined (5.6/1000 population)
  • DHB admission rates varied from between 1.5-fold to 2-fold.

2. Mortality following admission for physical injury, by DHB of domicile (NMDS), 2012–14

The analysis for this indicator shows:

  • approximately 270 people died in hospital each year
  • the national mean mortality rate was 1 percent
  • people aged 65 and over died more than 8 times more often than people aged under 65 years
  • there was little variation in mortality rates between DHBs.

Note: Due to low numbers, this indicator is only stratified by age at the national level and presented in Appendix 1 of the methodology.

3. Admissions due to physical injury, by DHB of service (NMDS), 2012–14

This indicator shows hospital admissions due to physical injury according to where people were treated.

The analysis for this indicator shows:

  • 26,783 people were admitted
  • DHBs admitted between 165 (West Coast DHB) and 3410 (Counties Manukau Health) people.
Major trauma injury indicators

Major trauma represents about 8 percent of all patients admitted to hospital with physical injuries.

Indicators 4–6 include only patients with major trauma injuries recorded in a hospital trauma registry between 2012 and 2014. The criteria used to define major trauma varied with the AIS coding standard used by each registry (eg, ISS >12 for AIS 1998 and ISS >15 for AIS 2008). Despite this, some discrepancies will remain and comparison between DHBs with different AIS coding standards should be treated with caution.

4. Admissions due to injury, by DHB of service (NZMTR), 2012–14

This indicator shows which of the hospitals with trauma registries treat the most major trauma cases. A high result is likely to reflect both hospital tertiary specialty and population size.

Over the three-year period:

  • 2065 major trauma admissions were recorded on the major trauma registries
  • twice as many males were admitted compared with females.

5. Mortality following admission with major trauma, DHB of service (NZMTR), 2012–14

Over the three-year period:

  • 182 trauma patients died, giving a mean mortality rate of 8.8 percent of major trauma cases registered
  • more than twice as many people aged 65 years and older died compared with all other age groups (18.2 percent of cases registered, compared with 6.6 percent of cases for 0–44 year olds)
  • there was no significant variation in the mortality rate between the DHBs.

6. Time from injury to first hospital capable of managing major trauma, DHB of service (NZMTR), 2012–14

This indicator shows the cumulative percentage of patients arriving at a hospital capable of managing major trauma within 48 hours. Time from injury to treatment should be as low as possible. Getting the patient to the right hospital at the right time is a vital principle of effective trauma care. Geography in New Zealand (topography, population density and, consequently, hospital location) predicates timing in some regions but improvements in trauma systems should see the time for patients to reach hospital decrease.

This indicator includes only data from the trauma registries in the Auckland region.

Over the three-year period:

  • 50 percent of major trauma cases arrived at a hospital capable of managing major trauma in less than an hour after the injury
  • 92.8 percent arrived at a hospital within three hours
  • most (95.4 percent) arrived at a hospital within six hours.

Summary

As the NZMTR becomes established and more consistent coding standards are implemented, more robust measures will become available. These will offer further quality improvement opportunities.

This Atlas domain prompts the following questions about trauma services in New Zealand:

  • Where are the deficits in trauma registry data in New Zealand?
  • Why are there differences in major trauma incidence between the districts and demographic groups?
  • How do these data compare with rates in similar overseas countries?
  • Where are the opportunities for improving major trauma care and outcomes?

Recommended reading

Royal Australasian College of Surgeons New Zealand Trauma Committee. 2012. Guidelines for a Structured Approach to the Provision of Optimal Trauma Care. URL: http://www.hqsc.govt.nz/assets/Other-Topics/QS-challenge-reports/Revised-Guidelines-for-Optimal-Trauma-Care.pdf.


References

  1. Ministry of Health and Accident Compensation Corporation. 2013. Injury-related Health Loss: A report from the New Zealand Burden of Diseases, Injuries and Risk Factors Study 2006–2016. Ministry of Health: Wellington.
  2. Baker SP, et al. 1974. The injury severity score: a method for describing patients with multiple injuries and evaluating emergency care. J Trauma, 1974. 14(3): p. 187-96.
  3. Palmer CS, Gabbe BJ, Cameron PA. 2015. Defining major trauma using the 2008 Abbreviated Injury Scale. Injury. DOI: 10.1016/j.injury.2015.07.003.

Last updated 03/10/2016