Worldwide incidence of traumatic brain injury could be six times higher than previous estimates


The first study to estimate rates of traumatic brain injury (TBI), without relying on official figures, has suggested that the worldwide incidence of TBI could be six times higher than previously estimated. The New Zealand population-based study, published online first in The Lancet Neurology, found that rates of TBI (790/100 000 people per year), and particularly mild TBI (749/100 000), were far higher than in other high-income countries in Europe (47–453/100 000) and North America (51–618/100 000).

“Our estimates are the first to include more mild cases of TBI that are not usually treated in hospital and, thus, are often overlooked in official estimates,” explained Valery Feigin, director of the National Institute for Stroke and Applied Neurosciences, AUT University, Auckland, New Zealand and research leader.

“It is the first study to show that 95% of all TBI cases are mild and that the true annual incidence of mild TBI is substantially higher than recent World Health Organisation (WHO) estimates (100–300/100 000 people per year). Based on these findings, we estimate that some 54–60 million people worldwide sustain a TBI each year, of which some 2.2–3.6 million people incur moderate or severe TBI. This is almost six times higher than previous estimates and means that every second two people in the world are struck by a new TBI.”

TBI is the leading cause of long-term disability among children and young adults and cost the USA alone an estimated US$406 billion in 2000. TBI is projected to become the third largest cause of disease burden worldwide by 2020.

The BIONIC (Brain injury outcomes New Zealand in the community) study examined multiple overlapping sources of information (eg, public hospitals, family doctors, rehabilitation centres, coroner/autopsy records, rest homes, ambulance services, and prisons) to record all new cases of TBI that occurred over a one-year period (1 March 2010 to 28 February 2011) in an area (173,205 residents) representative of the New Zealand population in terms of demographic, ethnic, socio-economic, and urban and rural structure.

Rates of TBI were highest in children (0–14 years old) and younger adults (15–34 years old), accounting for almost 70% of cases, far higher than the 40–60% reported in previous studies.

Men were nearly twice as likely to have a mild TBI as women, and almost three times as likely to sustain a moderate or severe TBI. Maori people also fared worse than New Zealand Europeans, with a 23% greater risk of mild TBI.

Consistent with previous reports, the new figures also indicate that people living in rural areas have more than twice the risk of moderate or severe TBI than those living in urban areas, mainly due to transport accidents.

According to Feigin, “Our analysis raises some very important issues, in particular that healthcare policy and provision may be grossly inadequate for the huge and growing burden of TBI worldwide. More comparable population-based studies of TBI are urgently needed to inform effective treatment, prevention, and rehabilitation strategies.”

Feigin expanded on this saying: “
Our research findings have some clear practical and research implications. For medical practice, our findings allow evidence-based planning and resource allocation for people with traumatic brain injury (eg, number of beds and services required for children and adults with acute brain injury) for a population served. Even more importantly, our findings showed that the true burden of traumatic brain injury is far greater than anybody anticipated and this is a time to act on developing more effective strategies to stop and, hopefully, reverse this silent epidemic. They also draw health-care policy makers’ attention to the need of public education about early symptoms of traumatic brain injury, especially mild injury, as well as the need for further development of effective strategies for brain injury prevention, with the emphasis on prevention of injuries due to falls in young adults and elderly. The unusually high proportion of brain injuries due to assaults also requires attention. For future research, our study underlines the obvious lack of prospective, truly population-based studies of traumatic brain injury incidence and outcomes and provides clear guidelines on how to conduct such studies in the most comprehensive and comparable way. Given the scope of the problem, more research is needed into the causes and management of traumatic brain injury.”

Nada Andelic, Oslo University Hospital, Norway, in a linked comment said that there is call for the development of national TBI surveillance systems to monitor trends and develop appropriate preventive measures, control strategies, and effective TBI care. She added, “A greater understanding of patient-specific characteristics is needed to reduce TBI risk at the individual level, and a focus on age, mechanism of injury, and severity-specific groups is needed to reduce the incidence of TBI at the population level.”