Epidemiology of traumatic brain injury in South Asia: A Systematic Review
1Department of Public Health, North South University, Dhaka, Bangladesh
2Department of Gastroenterology, Bangladesh Medical College, Dhaka, Bangladesh; Email: dr.sudeshnapurba@gmail.com
3Save the Children International, Dhaka, Bangladesh
4Department of Physiotherapy, National Institute of Traumatology & Orthopedic Rehabilitation (NITOR), Dhaka, Bangladesh
5Dhaka Medical College Hospital, Dhaka, Bangladesh
*Corresponding author: shahriar372@gmail.com (SH)Abstract
Background
Traumatic brain injury (TBI) is a serious global health problem contributing significantly to disability and death. No systematic review existed on epidemiology of TBI in South Asia, where accurate data were essential for planning healthcare policy and injury prevention programs.
Methods
This systematic review adhered to PRISMA guideline and received registration from PROSPERO (CRD42022364511). This review included observational from 1 January 1950 to 28 December 2024. A systematic search was performed on PubMed, Scopus, and Google Scholar and included studies fulfilling predetermined criteria. The methodological quality of the included studies was evaluated by Methodological Evaluation of Observational Research (MORE) checklist and result were presented as narrative synthesis.
Findings
Analysis of 130 studies reported a high incidence of TBI in South Asia primarily from road traffic accidents (RTAs). Prevalence ranged from 8.4% to 95.9%, with elevated case fatality and mortality rates. RTAs, falls and assaults were the leading cause of severe TBI. Adult males aged 21-30 years showed highest risk.
Conclusion
The results highlighted urgent necessity for standardized case definitions, improved data collection, and strengthened healthcare capacity in South Asia. Further research is required to understand long-term consequences and guide evidence-based public health responses.
Article notes
Competing Interest Statement
The authors have declared no competing interest.
Clinical Protocols
Funding Statement
This study did not receive any funding
Introduction
TBI is a major contributor to disability and death worldwide,1 and over 60 million individuals suffering from a TBI every year.2 The individuals surviving a TBI commonly experience prolonged physical, cognitive, and psychosocial disabilities.3 The treatment of TBI is complicated and costly, and its cost ranged throughout a person’s lifetime from $279 million to $1.22 billion.4
TBI is generally characterized as mild, moderate, and severe based on the Glasgow Coma Scale (GCS), a major prognosis predictor.5 However, novel approaches have been proposed for further precision in rating TBI severity.6 Newer tools, including advanced neuroimaging and biomarkers, are increasingly being combined with GCS scores.7,8
The epidemiology of traumatic brain injury (TBI) in South Asia is an emerging concern and rising rates have been documented in various countries in the region.9 Traumatic brain injury is an increasingly urgent public health problem due to urbanization, rising motorization, and poor safety infrastructure.10,11
South Asian traumatic brain injury (TBI) is diverse based on road infrastructure, economic conditions, and gaps in policy. Road traffic accidents (RTAs) are primarily responsible for causing it, with Bangladesh (62%), India (56%), and Nepal (59%) being heavily impacted.12–14
South Asian rates of traumatic brain injury (TBI) vary based on data collection differences, case definitions, and economic circumstances. Higher-income countries have superior data quality relative to lower-and middle-income countries (LMICs), resulting in more precise estimates.15,16
Inconsistent case ascertaining makes comparison challenging,17,18 whereas socioeconomic differences influence incidence and mortality.16,19 Standardizing case definitions and data collection using Common Data Elements (CDEs) enhances research quality as well as comparison.20,21 Standard practices and an improvement in healthcare infrastructure need to be instituted for improved management of TBI in South Asia.
High-quality observational research is essential for the understanding of TBI. Observational studies such as CENTER-TBI yield clinical and demographic data.22 TRACK-TBI and PRECISION-TBI biomarker analyses support individualized treatment.23,24 Observational studies contrast treatment outcomes25 and monitor recovery over the long term.26 Reliable and complete epidemiological data on South Asian TBI is vital for evidence-based planning at the level of public health as well as clinical management.14
Rapid urbanization and motorization and rising road traffic injuries resulted in a rising burden of TBI in the region, however available data remain fragmented and inconsistent. Recent advancements in healthcare infrastructure and the rising volume of observational studies conducted in the last few decades created a window of opportunity for a systematic review of existing evidence. Also, the absence of a previous systematic review on the subject points to an important gap in understanding the actual extent and magnitude of TBI in South Asia. With the pressure on public health systems to manage resources efficiently rising by the day, aggregating epidemiological data at present can be used to establish targeted prevention strategies. It can enhance trauma care and research directions for the future. This review therefore comes at a timely and imperative moment to facilitate policy-making informed by evidence and enhance clinical outcomes in the region. Our study addresses the following research questions:
- What is the prevalence of traumatic brain injury in South Asia?
- What is the mortality and case fatality of traumatic brain injury in South Asia?
- What is the severity and mechanism of injury of traumatic brain injury in South Asia?
- What are the age and sex distribution of traumatic brain injury in South Asia?
4.Methods
Registration and Protocol
This systematic review was reported and executed according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) Statement.171 The protocol for this systematic review was registered on PROSPERO (registration number 2022: CRD42022364511). It can be accessible at https://www.crd.york.ac.uk/prospero/display_record.php?ID=CRD42022364511
Search strategy and inclusion criteria
The databases searched included PubMed, Google Scholar and Scopus from January 1, 1950 through December 28, 2024. For all of them, combined key words and MeSH terms (S1 Appendix) were used for searching. To minimize publication bias risk, reference lists in included studies also were searched. The studies included were observational in nature, encompassing cross-sectional, case-control, and cohort designs. Studies providing retrospective and prospective descriptive data on the epidemiology of TBI in South Asia were included. To qualify for this research, studies also had to be an original study, have measured and reported on prevalence, mortality, case fatality, severity, and mechanism of injury of TBI in South Asia. There were no exclusions based on study size as data from hospitals, police records, relatives/persons accompanying them were included. Also, there were no exclusions based on dates of data, study performance and publication dates, age of participants, nor based on TBI severity.
For certain of those terms, including TBI, incidence, mortality, and case fatality, definition among authors was varied. For the purposes of this research, these terms were defined in the following ways:
- ⍰ TBI: An injury to the head by blunt or penetrative injury causing enough harm so that the patient experiences a change in brain function; alternatively, more recently, as a change in brain function, or other indication of brain pathology due to an external pressure.27 Ascertainment of a case of TBI might be through any one of the following: clinical diagnosis based on history and physical examination and imaging (CT scan, X-ray scans, MRI), autopsy, Glasgow coma scale (GCS), CDC criteria, ICD 9th and 10th revision codes and others.
- ⍰ Case fatality: Proportion of people with TBI who subsequently died due to a cause related to the TBI at certain time-points.
- ⍰ TBI severity: Categories of severity (severe, moderate, mild), as defined by the GCS or other classification system used by the authors.5
Exclusion criteria
Exclusion of studies were based on numerous criteria. First, those not from South Asia were excluded in order to be regionally relevant. Non-primary research studies, reviews, meta-analysis, and grey literature were excluded in order to secure primary data of observational studies. Studies without data on key outcomes, prevalence, mortality, case fatality, severity, or mechanism of injury were excluded. Those studies with inconsistent TBI case definitions or poor ascertainment methods were also excluded in order to ensure reliability. Studies with poor methodical reporting or ambiguous sampling and diagnostic requirements were also excluded in order to secure quality. The above exclusions ensured only studies of relevance, reliability, and quality were included in this review.
Screening and study selection
SH and SCP completed the initial screening of titles and abstracts to select studies that met inclusion criteria. Non-eligible studies were excluded and included studies were selected for full-text review. RH and MEH independently assessed study methodologies and reported results from full-texts to ensure eligibility. Disagreements were resolved through consensus and discussion.
Data Analysis
FS and KMYA extracted data from included studies using a standard data extraction form extracting study features, participant information, methodological details, and outcome data. MMM and JAI checked extracted data for accuracy and completeness by referencing against source articles. Discrepancies were discussed and resolved jointly. SH, SCP, RH, FS, KMYA, MMM, and JAI synthesized extracted data into an integrated narrative overview centered on primary epidemiological variables. They made sure that synthesis was thorough and all pertinent data were included.
SH, RH, MMM and JAI evaluated included study quality. The methodological quality of included studies was assessed using the Methodological Evaluation of Observational Research (MORE) checklist that has been utilized in an earlier systematic review.17 The checklist evaluated a number of areas related to bias or quality, including study aim, funding of study, conflict of interest, ethical clearance, study design, sampling, case definition, bias addressed, data sources, reliability of estimates, incidence and mortality. Each area was ranked according to specific criteria and scored as “OK, Minor Flaw, Major Flaw, or Poor reporting” (Appendix 2). No studies were removed from this research based on their methodological quality.
Narrative synthesis was written on this review findings. All data on prevalence, mortality, case fatality rates, severity and mechanism of TBI as well as important demographic information on age and sex distribution were extracted. Quantitative data on TBI outcomes were synthesized through categorization of results by prevalence rates, mortality and case fatality rates and severity classification (mild, moderate and severe) and mechanism of injury (e.g., road traffic accidents, falls and assaults).
Role of the funding source
There was no funding source for this study.
Ethical Considerations
This study is a systematic review of previously published data. All data were extracted from publicly available literature. Therefore, institutional review board approval and direct patient consent were not required for this study. The included primary studies were evaluated for their reporting of ethical approval. As this is a systematic review, it is not a clinical trial and does not require registration in a clinical trial registry. The review protocol was registered with PROSPERO.
5.Results
A total of 1347 articles were identified. After removing duplicates, 1122 were screened on title and abstract and 893 were excluded. Subsequently, 229 papers were screened for full-text eligibility, with 130 articles finally included in this review (Fig. 1).
Country Variation
The revies included studies from Bangladesh, India, Nepal, Pakistan and Sri Lanka. Studies from three more countries in South Asia, Afghanistan, Bhutan, and Maldives, were not part of this research. Though they were under consideration for inclusion, no articles from these countries met predetermined inclusion criteria. These countries thus did not represent in this final list of included studies for review.
Sample Size
The extensive range in sample size (from 10 up to 260,000) indicates heterogeneity in research scope on a large scale.
Study period
A total of 126 out of 130 studies in this research reported the duration for which data were collected. The average duration study periods were about 2.66 years. The study periods ranged from 1 to 22 years, showing variation in observation periods. Most studies focused on a relatively brief observation period. With regard to frequency, 1–3 year durations were most common. Among them 42 studies reported 2 years, 29 studies reported 1 year and remaining 29 studies had 3-year duration. These three durations contributed more than 78% of studies with valid duration data and demonstrate a strong tendency towards short-term investigations. Conversely, extended-term studies were rare. Only 11 studies reached 4 years, 9 studies reached 5 years, 2 studies reached 6 years and only 2 studies extended to 9 and 22 years, constituting an unusual instance of lengthy surveillance.
Data sources
Data for most came from hospital records, including medical histories, patient records, and treatment charts. Autopsy records and reports came into play to evaluate fatal cases in many instances. Police records in the form of inquest reports and dead body challans added to the clinical data. Structured questionnaires, self-structured proformas, clinical examination, and CT scan reports were among other data sources. Telephone interviewing was also included by some studies.
Inclusion Criteria
This study illustrates considerable heterogeneity among the studies, mirroring diversity in patient selection for TBI cases based on age, injury severity, clinical setting, and injury mechanism. Although some studies confined themselves to moderate to severe TBI alone, others included mild head injury cases as well as cases from all severities. Inclusion criteria differed by age groups as well, with some studies focusing on pediatric populations (<18 years), while others targeted adult and older populations (>60 years). These age-based subgroup distinctions help elucidate how age plays a role in susceptibility to as well as recovery from TBI and are important when interpreting age-specific risk factors and outcome patterns. Furthermore, numerous studies select based on clinical admission category, such as those admitted to ICUs or neurosurgical departments. Mechanisms involving road traffic accidents (RTAs) and falls were readily listed as inclusion criteria. These are common injury mechanisms in South Asia. The time since injury was another inclusion criterion with considerable heterogeneity. While most studies included acute TBI cases within 24 to 48 hours post-injury, others included patients with a more prolonged duration of injury from any hour to days post-injury and even included surgical cases. Such broad variation in inclusion could affect generalizability and comparability among studies.
TBI definition/ Case ascertainment
The severity of TBI was assessed primarily through Glasgow Coma Scale (GCS) and supplemented regularly by CT scans, X-rays, and MRI scans. Clinical examination and autopsies were included as part of many studies to determine injuries such as skull fractures and intracranial hemorrhages. Furthermore, tools including Glasgow Outcome Scale (GOS), Kampala Trauma Score (KTS), TRISS, and FOUR score were used to quantify severity and outcome.
Methodological quality
Based on the MORE checklist, all included studies described their aims clearly (99.2%) and used proper study designs (100%), while ethical approval and conflict of interest were reported well (91.5% and 84.6%, respectively). Funding information reporting was poor (96.2%), while sampling exhibited significant flaws with 98.5% receiving minor flaws ratings. Definitions for cases and classifications for TBI severities were good (>93%), but management of bias was a critical flaw and 99.2% exhibited major flaws. Data sources and subject flow were reported well (97.7%). Reliability of estimates and reporting of mortality were less good with more than 60.8% and 24.5% exhibiting flaws, respectively.
Prevalence
In this systematic review, 130 selected articles presented different prevalence rates for traumatic brain injury (TBI). While most study reported 100% prevalence on the selected study population, each representing uniform occurrence among the study populations, others reported prevalence rates ranging from 8.4% to 95.9%.
Mortality and case fatality rates
A total of 101 studies reported mortality rates. Mortality in studies included in this study varied significantly, as expected given differences in study design, target populations, and case severity being studied. Total 29 studies did not report mortality data.
Type of severity
The severity distribution of traumatic brain injuries (TBI) across the studies shows considerable variation. A total 95 studies reported severity data with detailed categorizations. The most frequent distribution shows a focus on mild, moderate, and severe injuries, with varying proportions in different studies.
Mechanism of TBI Injury
The injury mechanism for TBI is dominated strongly by road traffic accidents (RTAs) as the predominant source of injury in South Asia. There were 12 studies, and they reported 100% of cases attributed to RTAs,33,45,94,111,116,117,122,124,125,129,140,157 confirming road traffic injury’s high burden in the region. Aside from RTAs, some studies included fall from height as a major source of injury. Violence or assault as a factor was reported by some studies but less commonly included.
Age and sex
The average age of participants in studies included in this systematic review is highly variable and indicates diverse populations under investigation. The age in studies ranges from pediatric populations with average ages as low as 4.7 years to elderly populations with average ages as high as 71.08 years. The majority of studies target younger populations with ages in their 20s and 30s as indicated by commonest average age values of 24 and 28.9 years. Nevertheless, a few studies target adolescents and children with average ages of 15 and 4.7 years as an indication that pediatric TBI is their focus. The gender split throughout the studies is dominated by male participants, and most studies report 70% and above male participants. For instance, 78% is the most frequent male proportion, and most studies reveal male proportions ranging from 65% to 88%. Female proportions tend to be a smaller percentage and usually 22% or below.
Discussion
This systematic review fully explored the epidemiology of traumatic brain injury (TBI) in South Asia. Despite significant methodological limitations in the primary studies, suggests that TBI is a major public health concernin the region as indicated by high rates of prevalence among young adults. Road traffic accidents (RTAs) were found to be the primary source of TBI in countries in South Asia as a whole, including Bangladesh, India, and Nepal which recorded especially high rates involving traffic injuries leading to TBI. Mortality differed, however, the burden of TBI as indicated by case fatality and disability over a prolonged period after injury was high. Our systematic review further highlighted that severity ranges of TBI in the region were mostly found to be mild to moderate while a large number of cases also presented with severe injuries.
This systematic review indicated that TBI was a considerable public health problem in South Asia with variable prevalence rates among countries. The prevalence of TBI within the region was significantly high, particularly among countries with inadequate infrastructure and poor road safety policies.158 The rapid urbanization and motorization in South Asia further fueled the cases of TBI and road traffic accidents (RTAs) were predominant causes in most studies.155 TBI is more common in other regions, such as United States. In a systematic meta-analysis including a general adult population, about 18.2% (95% CI 14.4-22.7%) adults reported a lifetime history of TBI with loss of consciousness.159
The case and mortality rates due to TBI in South Asia were very high. There was wide variation in these rates in the systematic review, with severe cases of TBI being a major driving factor for mortality. Traumatic brain injury is also a major cause of death and disability worldwide despite accurate worldwide mortality rates being highly variable according to geographical region, healthcare system, and reporting policies. Mortality due to TBI is calculated in a systemic review to be 20-30% worldwide.160 The crude mortality rates in Europe ranged from 9 to 28.1 per 100,000 population per year.161 A study discovered that TBI now stands as the leading cause of mortality in instances of polytrauma as evidence indicates a change in patterns among trauma-related deaths.162 They reported 66% (70/106) among all trauma-related mortality.162
In terms of their severity, most cases of TBI among South Asians were mild or moderate but a large percentage also included severe injuries. The distribution according to severity differed among countries and regions and an area might record a greater percentage of severe injuries. This inconsistency might have been due to variations in case ascertainment approaches that involved use of Glasgow Coma Scale (GCS) scores and high-tech imaging modalities such as CT and MRI scans. The injury severity in TBI was found to be directly associated with outcome, and the results indicated more severe injury in most instances leading to an extended duration of stay in the hospital, higher healthcare expenditure, and prolonged disabilities.
The major mode of TBI throughout South Asia was road traffic accidents (RTAs), followed by falls and assaults. RTAs specifically contributed to more than half of the cases with motorcycles being the leading vehicle implicated in TBI. These study results coincide with other studies. A meta-analysis LMICs reported 39% pediatric TBI cases due to RTAs.19 In Ethiopia, 21% of TBI cases were due to RTAs.163 A bibliometric study involving research on TBI indicated RTAs as the most common source of TBI over falls among older populations in line with the evidence.160 The predominance of RTAs in South Asia was driven by inadequate road infrastructure,164–166 poor protective precautions such as helmet.167
TBI affected all ages but varied significantly depending on age and sex. This systematic review found high incidences among young adults and especially males that align with results in previous studies. One study found that young adults and especially men and older people are high-risk groups for TBI.168 In line with a systematic review and meta-analysis involving all major studies up to 2023, males account for about 74.3% of all cases of TBI and create a male-to-female ratio close to 3:1.169 One meta-analysis found that prevalence among genders differed and that males recorded a higher percentage at 20.8%.159 Several studies have discovered age as a major factor in determining TBI outcome. In a recent systematic review and meta-analysis, age is a major determinant with an average age gap of 8.72 years among patients.170
This review utilized multiple databases to ensure comprehensive coverage of studies from various countries from the region of South Asia. It also had specific research aims centred on important TBI epidemiologic outcomes so a meaningful synthesis could be achieved. This review utilized the PRISMA approach and also employed a rigorous data extraction method for ensuring methodological quality. By considering different study designs like cross-sectional, cohort, and case-control studies, it captured data from a variety of settings from South Asia. The application of the MORE checklist for assessing study quality assured even more rigor and ensured the incorporation of accurate studies.
Major limitations of the present systematic review were the considerable heterogeneity in included studies in relation to study design, data sources, case definitions, TBI measurement method which hampered quantitative synthesis. Dissimilarities in the report of TBI outcomes like prevalence, mortality, severity, and mechanism of TBI injury also hampered comparison. The quality of the studies varied methodologically in relation to sampling and case and data reliability biases. Longitudinal follow-up data were missing from most studies, hence limited the estimation of outcomes like disability or recovery.
TBI in South Asia presented as a severe public health concern with high prevalence, high mortality, and variable severity and was most commonly due to road traffic accidents. This research results highlighted greater need for better infrastructure for trauma care, preventive efforts towards road safety, and recognition towards high-risk groups including young adults, children and older adults. Priority policy interventions towards strengthening road safety, increasing numbers of trauma care facilities, and enhancing data collection were necessary to reduce the burden of TBI in the region. Future studies should incorporate standardized approaches to collecting data on TBI and longitudinal studies to further understand late consequences and outcomes for survivors of TBI.
Contributors
SH and SCP conceptualized the study. SH, SCP, RH, and MEH performed title, abstract, and full-text screening. FS and KMYA conducted data extraction, and MMM and JAI verified the extracted data. SH, RH, FS, KMYA, MMM, and JAI synthesized the results. SH, RH, MMM and JAI assessed the risk of bias. SH drafted the manuscript, and SCP critically reviewed it for intellectual content. All authors read and approved the final manuscript, jointly decided to submit the paper, and agreed to be accountable for all aspects of the work.
Data sharing statement
The findings of this study are based entirely on data from previously published studies, all of which are publicly accessible and referenced within this manuscript. No new primary data were collected or analyzed in this systematic review. Additional information or detailed data extraction materials used in this review can be provided upon reasonable request to the corresponding author.
Declaration of interests
All authors declare no competing interests.
Supporting information
Data Availability
The findings of this study are based entirely on data from previously published studies, all of which are publicly accessible and referenced within this manuscript. No new primary data were collected or analyzed in this systematic review. Additional information or detailed data extraction materials used in this review can be provided upon reasonable request to the corresponding author.
Acknowledgment
We thank Marzana Afrooj Ria, our information specialist, for her assistance with the search strategy.