Clinically Seriously Injured (MAIS 3+) Road Casualties in Northern Ireland, 1999-2017 has been published today

Date published: 27 June 2019

Clinically Seriously Injured (MAIS 3+) Road Casualties in Northern Ireland, 1999-2017 is now available. This bespoke analysis supplements the NI Road Safety Strategy (NIRSS) to 2020 Annual Statistical Report.

Publication of Travel Survey for Northern Ireland 2012-2014 headline report

The publication is available on the Analysis, Statistics and Research Branch website at

Key Points

Trend Information

  • Examining the data from 1999 to 2017, the number of clinically seriously injured (MAIS 3+) road casualties admitted to hospital in Northern Ireland peaked in 2002 with 235 serious injury (SI) casualties, after which numbers began to fall to the series low of 62 in 2013.
  • Recent years would indicate that the historic downward trend may now be levelling off or increasing: in the latest available year, 2017, there were 89 MAIS 3+ casualties – the highest recorded since 2012 and an increase of 31% since 2016.
  • Overall, 8% of hospital admissions for road traffic collisions in the last five years had injuries classified as MAIS 3+; however, the proportion differs by road user type, with motorcyclists having the greatest proportion of admissions that were MAIS 3+ (10%) and pedal cyclists the fewest (6%).
  • Comparing the number of hospital admissions to police reported serious injuries we see that a significant proportion (around 30%) of SI casualties are not known to the police. This under-reporting issue has been noted across many jurisdictions including GB and RoI.

MAIS 3+ Casualty Profile

In 2013-2017:

  • Males accounted for just over seven-tenths (72%) of the total MAIS 3+ casualties in Northern Ireland in the five years from 2013 to 2017. This is greater than the proportions of male casualties reported in overall hospital admissions (65%) and PSNI serious injuries (64%).
  • Almost three-in-ten (28%) MAIS 3+ casualties were aged 70 and over. This differs markedly from the age profile of overall hospital admissions for road traffic collisions and PSNI serious injuries, where 12% and 10%, respectively, were in this age band.
  • The most frequently recorded road user type of the MAIS 3+ casualties was car (48%). However, the equivalent proportion of PSNI Serious Injuries is 58%. Therefore, the numbers of casualties that were travelling by the more vulnerable modes (pedestrian, motorcycle and pedal cycle) made up a greater proportion of the MAIS 3+ total than they did of the PSNI SIs (44% compared with 40%, respectively).
  • Comparing NI road traffic casualties with England, we see that MAIS 3+ casualties in NI account for a smaller proportion of police reported seriously injured than in England: 10% in NI compared with 26% in England.
  • The report presents two possible reasons for this difference: firstly, there appears to be greater underreporting of police serious injuries in England than in NI; and secondly, the profile of the road user type differs across the two jurisdictions, with a smaller proportion of vulnerable road users (pedestrian, cyclist and motorcyclist) in the NI police data being reflected in fewer MAIS 3+ hospital admissions here.

Notes to editors: 

  1. Clinically Seriously Injured (MAIS 3+) Casualties in Northern Ireland, 1999-2017 is the third in series, and presents the 2017 update. 
  2. The MAIS 3+ data included in this report are produced using casualty admissions to hospitals in Northern Ireland, between 1999 and 2017, with a clinically defined serious injury following a road traffic collision.
  3. The Abbreviated Injury Scale (AIS) is the clinical measure used to classify and describe the severity of injuries; it represents the threat to life associated with the injury. A score of 1 indicates a minor injury, while 6 refers to an unsurvivable injury. A casualty that sustains an injury with a score of 3 or higher on the AIS is classified as clinically seriously injured (MAIS 3+).
  4. The majority of the data within the report derives from the Department of Health Hospital Admissions data, and is typically based on the period 1 January 1999 to 31 December 2017. The report first looks at the overall trend in MAIS 3+ casualty numbers, and then examines the profile of casualties (gender, age, road user type). A comparison with PSNI reported serious injuries for road traffic collisions, and MAIS 3+ casualties in England is also presented.
  5. The information in this publication can be used to make international comparisons of the numbers of people that are seriously injured as a result of road traffic collisions. The MAIS 3+ clinical definition of a serious injury is currently recommended by the EU, rather than police reported data, because there are significant differences in the grading of severity of injury that are applied in police data in each country.
  6. Further information and electronic copies of Clinically Seriously Injured  (MAIS 3+) Road Casualties in Northern Ireland, 1999-2017 are available at:
  1. For more information relating to this publication, including additional analysis, breakdowns of data, or alternative formats please contact:
Analysis, Statistics and Research Branch,
Room 4.13c,
Clarence Court,
10 - 18 Adelaide Street,
Town Parks
BT2 8GB     


  1. All media queries should be directed to the Department for Infrastructure Press Office on 028 9054 0007 or email: Out of hours please contact the duty press officer on 028 9037 8110.

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