Elsevier

The Lancet Neurology

Volume 12, Issue 1, January 2013, Pages 53-64
The Lancet Neurology

Articles
Incidence of traumatic brain injury in New Zealand: a population-based study

https://doi.org/10.1016/S1474-4422(12)70262-4Get rights and content

Summary

Background

Traumatic brain injury (TBI) is the leading cause of long-term disability in children and young adults worldwide. However, accurate information about its incidence does not exist. We aimed to estimate the burden of TBI in rural and urban populations in New Zealand across all ages and TBI severities.

Methods

We did a population-based incidence study in an urban (Hamilton) and rural (Waikato District) population in New Zealand. We registered all cases of TBI (admitted to hospital or not, fatal or non-fatal) that occurred in the population between March 1, 2010, and Feb 28, 2011, using multiple overlapping sources of information. We calculated incidence per 100 000 person-years with 95% CIs using a Poisson distribution. We calculated rate ratios [RRs] to compare the age-standardised rates between sex, ethnicity, and residency (urban, rural) groups. We used direct standardisation to age-standardise the rates to the world population.

Results

The total incidence of TBI per 100 000 person-years was 790 cases (95% CI 749–832); incidence per 100 000 person-years of mild TBI was 749 cases (709–790) and of moderate to severe TBI was 41 cases (31–51). Children (aged 0–14 years) and adolescents and young adults (aged 15–34 years) constituted almost 70% of all TBI cases. TBI affected boys and men more than women and girls (RR 1·77, 95% CI 1·58–1·97). Most TBI cases were due to falls (38% [516 of 1369]), mechanical forces (21% [288 of 1369]), transport accidents (20% [277 of 1369]), and assaults (17% [228 of 1369]). Compared with people of European origin, Maori people had a greater risk of mild TBI (RR 1·23, 95% CI 1·08–1·39). Incidence of moderate to severe TBI in the rural population (73 per 100 000 person-years [95% CI 50–107) was almost 2·5 times greater than in the urban population (31 per 100 000 person-years [23–42]).

Interpretation

Our findings suggest that the incidence of TBI, especially mild TBI, in New Zealand is far greater than would be estimated from the findings of previous studies done in other high-income countries. Our age-specific and residency-specific data for TBI incidence overall and by mechanism of injury should be considered when planning prevention and TBI care services.

Funding

Health Research Council of New Zealand.

Introduction

Traumatic brain injury (TBI) is the leading cause of long-term disability in children and adults younger than 35 years,1, 2, 3 and has serious effects on the lives of patients, their families and friends, and society.4, 5, 6 An estimated 10 million people worldwide are affected every year by a new TBI event.3 Projections indicate that TBI will become the third largest cause of global disease burden by 2020.7 In the USA, an estimated 1·7 million people sustain a TBI annually,8 and about 5·3 million people live with a disability related to TBI.1 The incidence of TBI is estimated to be 200–558 per 100 000 population,9, 10, 11 with estimated overall economic cost in 2000 of about US$406 billion.12

Previous estimates of TBI incidence have been mainly based on official statistics (eg, patients admitted to hospital for TBI) and were prone to diagnostic and selection biases.13, 14 The true incidence of TBI is widely acknowledged to be higher than available estimates,3, 15, 16 because 70–90% of all TBIs are mild,4, 16 with only a small proportion of those affected by TBI being admitted to hospital.14, 15, 17, 18 However, even so-called mild TBI can result in long-term deficits.19, 20, 21, 22 Indeed, the National Institutes of Health declared in 1999 that mild TBI is a major public health problem,2 emphasising the importance of capturing the true burden of TBI in the population.15, 23 Available evidence also suggests ethnic inequalities in TBI incidence and outcomes,24, 25, 26 but accurate community data for such disparities in TBI burden are scarce. TBI should, therefore, be studied in a population-wide context, providing more robust estimates of incidence, outcomes, and the true burden borne by various communities.3, 11, 27, 28, 29, 30, 31 We aimed to estimate age-specific, sex-specific, and ethnic-specific rates of mild and moderate to severe TBI in the Brain Injury Outcomes New Zealand In the Community (BIONIC) study—a large, population-based, TBI incidence and outcomes study undertaken in New Zealand during 2010–11.

Section snippets

Study participants

The study population included people of all ages in a large geographical area in the central North Island of New Zealand, including the city of Hamilton (129 249 people, 98 km2) and the surrounding rural area (Waikato District, 43 956 people, 31 987 km2; appendix). In the study area, Europeans constituted 55% of the study population, Maori 20% (the indigenous population of New Zealand), Pasifika (Pacific Islands people living in New Zealand) 2%, and people of other ethnic origins 15%. By its

Results

Of the 1369 individuals with TBI, most were boys and men, individuals younger than 35 years (69% [943]), urban residents (74% [1008]), and of European ethnicity (61% [837], table 1). Most patients had mild TBI (95% [1298]). Moderate and severe TBI were most common in individuals older than 15 years (90% [64 of 71]); mild TBI was most prevalent in individuals aged 15–34 years (40% [523 of 1298]). A substantial proportion of patients with TBI (36% [487 of 1369]) did not present to hospitals at

Discussion

To our knowledge, this study is the first large population-based study to investigate TBI incidence across the spectrum of severity in all age groups in a geographical region with urban and rural populations. The most important finding of our study was that the incidence of TBI per 100 000 people per year (790 cases), especially mild TBI (749 cases), in New Zealand was substantially greater than in other high-income countries in Europe (47–453 cases)29, 39, 40 and North America (51–618 cases).3

References (52)

  • AA Hyder et al.

    The impact of traumatic brain injuries: a global perspective

    NeuroRehabilitation

    (2007)
  • H von Holst

    Traumatic Brain Injury

  • J Donders et al.

    Neurobehavioral outcomes after early versus late childhood traumatic brain injury

    J Head Trauma Rehabil

    (2007)
  • Traumatic brain injury: time to end the silence

    Lancet Neurol

    (2010)
  • JF Annegers et al.

    The incidence, causes, and secular trends of head trauma in Olmsted County, Minnesota, 1935–1974

    Neurology

    (1980)
  • DJ Thurman et al.

    Traumatic brain injury in the United States: a public health perspective

    J Head Trauma Rehabil

    (1999)
  • CL Leibson et al.

    Incidence of traumatic brain injury across the full disease spectrum: a population-based medical record review study

    Epidemiology

    (2011)
  • P Corso et al.

    Incidence and lifetime costs of injuries in the United States

    Inj Prev

    (2006)
  • GM Ribbers

    Traumatic brain injury rehabilitation in the Netherlands: dilemmas and challenges

    J Head Trauma Rehabil

    (2007)
  • JD Cassidy et al.

    Incidence, risk factors and prevention of mild traumatic brain injury: results of the WHO Collaborating Centre Task Force on Mild Traumatic Brain Injury

    J Rehabil Med

    (2004)
  • R Vink et al.

    Novel therapies in development for the treatment of traumatic brain injury

    Expert Opin Investig Drugs

    (2002)
  • JJ Bazarian et al.

    Mild traumatic brain injury in the United States, 1998–2000

    Brain Inj

    (2005)
  • CW Hoge et al.

    Mild traumatic brain injury in U.S. Soldiers returning from Iraq

    N Engl J Med

    (2008)
  • BM Stålnacke et al.

    One-year follow-up of mild traumatic brain injury: cognition, disability and life satisfaction of patients seeking consultation

    J Rehabil Med

    (2007)
  • F Rivara

    Counterpoint: minor injuries may not be all that minor

    Inj Prev

    (2011)
  • JF Annegers et al.

    A population-based study of seizures after traumatic brain injuries

    N Engl J Med

    (1998)
  • Cited by (0)

    View full text