Demographics, Causes, and Outcome of Traumatic Brain Injury among Trauma Cases in Cameroon: A Multi-Center Five Year's Retrospective Study

Traumatic brain injury (TBI) is a huge public health challenge worldwide. Epidemiological monitoring is important to inform healthcare policy. We aimed at determining the prevalence, outcome, and causes of TBI in Cameroon by conducting a 5-year retrospective study in three referral trauma centers. Data on demographics, causes, injury mechanisms, clinical aspects, and discharge status were recorded. Comparisons between two categorical variables were done using Pearson's chi-square test or Fisher's exact test. A total of 6248 cases of TBI were identified of 18,151 trauma cases, yielding a prevalence of 34%. The number of TBI cases increased across the years (915 in 2016, 1406 in 2020). Demographic data and causes of TBI were available for 6248 subjects and detailed data on clinical characteristics on 2178 subjects. Median age was 30.0 (24.0, 41.0) years. Males were more affected (80%). Road traffic incidents (RTIs; 75%) was the main cause of TBI, with professional bike riders being more affected (17%). Computed tomography (CT) imaging was performed in 67.7% of cases. Of the 597 (27.4%) cases who did not undergo neuroimaging, 311 (52.1%) did not have neuroimaging performed because of financial constraints, among which 7% were severe TBI cases. A total of 341 (19.6%) patients were discharged against medical advice, of which 83% had financial limitations. Mortality was 10.3% (225 of 2178) in the overall population, but disproportionately high in patients with severe TBI (55%) compared to those in high-income settings (27%). TBI occurrence is high in Cameroon, and RTIs are the main causes. Disparities in care provision were identified as attributable to financial constraints regarding CT scanning and continuation of care. The data presented can inform preventive interventions to improve care provision and transport policies. Implementation of a universal health insurance may be expected to improve hospital care and reduce the adverse effects of TBI among Cameroonians.


Introduction
Traumatic brain injury (TBI) is a growing public health challenge worldwide, 1,2 and *69 million persons globally sustain a TBI each year. 3 It is a leading cause of death and disability worldwide. [4][5][6] An estimated 5 million persons seek medical attention in the United States, 7 up from 2.8 million reported by Plog and colleagues 1 in 2015 and 2016, with *3.2 million persons reported as living with disability after TBI. [8][9][10] TBIs are an important medical, societal, and socioeconomic problem worldwide, rendering epidemiological monitoring of incidence, prevalence, and outcome important. 2,4 Age-standardized incidence of TBI increased globally by 3.6% between 1990 and 2016. 11 The crude incidence rate per year in Europe ranges from 83.3 to 849 per 100,000 populations at regional levels. 12 TBI, often referred to as a ''silent epidemic,'' 13 has a lifetime prevalence of 40% in adults and is approximately 2 to 3 times more frequent in male subjects than in females. [14][15][16] Although the burden of TBI is felt globally, it affects low-and middle-income countries (LMICs) disproportionately compared to high-income countries (HICs), with higher mortality rates in LMICs (18% in LMICs and 11% in HICs). 17 In Sub-Saharan Africa (SSA), mortality attributable to TBI is high: 77% for severe TBI, 16% in moderate, and 1% in mild. 18 The burden of TBI is high in Africa as a whole and SSA in particular, but detailed data are lacking. Currently, around one tenth of deaths in Africa are secondary to motor vehicular injury, although Africa has just 4% of the world's vehicles. 19 Moreover, SSA is considered the global capital of road traffic deaths, most of which involve a TBI, 20,21 and it is projected that the incidence of TBI will rise to 14 million yearly in SSA by 2050, up from the 3.2 million reported recently. 22 This rapid increase will result in more TBIs and make SSA a focus of global attention. 23 Cameroon, being the epicenter of SSA, is still faced with several infrastructural problems especially in terms of road infrastructure. 24 More so, an important part of its population is young and unemployed, which exposes youths to hazardous income activities, such as professional bike riding, increasing their risk to trauma of all types including TBI. More so, poor outcome, especially in the youthful population, is likely given that they are often not able to pay for healthcare given the high cost and cannot afford private insurance ser-vices because there is not yet universal health coverage in Cameroon. Adegboyega and colleagues, 25 in Cameroon, attempted to estimate the burden of TBI in SSA, but their review was limited to management, followup, and training and did not address the prevalence, incidence, causes, and outcome of TBI in SSA.
Prevalence of TBI in Sub-Saharan urban population was 19% in 2013 (841 TBIs of 4411 trauma cases), 26 lower than the prevalence (30.9%) of TBI (415 of 1344 trauma cases) reported in a West African country. 27 Abate and colleagues 28 reported a prevalence of 20% in Ethiopia. These disparities in reported prevalence rates in the few studies conducted in SSA may indicate a problem of underestimation. Large, epidemiological multi-center studies considering several years are needed for a more accurate determination of the prevalence of TBI, to inform prevention and healthcare policy.
Therefore, the study aimed at determining the prevalence, main causes, and discharge status of patients with TBI in a period of 5 years from 2016 to 2020 in three level 1 trauma centers of Cameroon.

Study area, design, and period
We conducted a 5-year retrospective study in three referral hospitals in Cameroon. Data were collected from January 1, 2016 to December 31, 2020 in three referral hospitals of urban Yaoundé (Yaoundé Military Hospital; YMH) and Douala (Douala General Hospital [DGH] and Laquintinie Hospital of Douala [LHD])-Cameroon. These hospitals were selected because they are located in two cosmopolitan, densely populated cities of Cameroon: Douala and Yaoundé, the economic and political capitals of the country, respectively. Douala, with an estimated population of *3.8 million inhabitants, 29,30 is situated on the south-eastern shore of the Wouri river estuary, on the Atlantic Ocean coast *230 km west of Yaoundé. It has a wet and a dry season and has temperatures ranging from 23°C to 33°C. Yaoundé, with a population of >4 million inhabitants, 31 is situated in a hilly, forested plateau between the Nyong and Sanaga rivers in the south-central part of the country. Just like Douala, it has two seasons; a wet overcast and a dry cloudy, with temperatures varying across the year from 19°C to 31°C. 32 These hospitals are reputed to receive most of the cases of all types of trauma given that they are among the few hospitals in the country with the required technical level needed for trauma care. In addition, they are also among the few hospitals in the country that have fully functional neurosurgical units. The DGH is a level 1 trauma center with three neurosurgeons, a multi-slice computed tomography (CT) scanner, and 0.4-Tesla (T) magnetic resonance imaging (MRI). The LHD has three neurosurgeons, a CT scanner, and 0.5-T MRI, and the YMH has two neurosurgeons, a scanner, and 0.5-T MRI.

Study population
The population included persons of all ages who were seen with a traumatic injury who were seen within the study period, in the different health structures considered. Exclusion criteria were all non-TBIs, files lacking key information like age and sex, and obstetrical trauma. The files of patients who sustained trauma were screened and the number of cases recorded for prevalence calculations.

Data collection
All files of patients who sustained a traumatic incident over a period of 5 years ( January 1, 2016 to December 31, 2020) from the three different services of the DGH and YMH, considered to be the routine care path of TBI patients within the hospital-the emergency, reanimation, and neurosurgical services-were considered. Information concerning sociodemographic characteristics of patients (age, sex, profession, marital status, religion, and nationality) and vital signs were abstracted and recorded in the case report forms (CRFs). Hypothermia was considered to be temperatures <35°C, normal temperatures between 35°C and 37.9°C, and high temperatures or fever as from 38°C. 33 At the DGH, patient files were registered by month and year; that is, January to December of each year in all three services that constitute the normal circuit of trauma patients at the DGH: emergency, surgery, and reanimation. Therefore, at a given year, we proceeded by reviewing all files monthly, from which we selected TBI cases and other traumatic cases. Trauma cases for each month were counted and recorded. Once data were extracted from TBI files to CRFs, we reclassified the files and moved to another month going from 2020 to 2017. Because of the ill-handling of files by previous research students, files of 2016 were missing at the DGH. Therefore, only registers for 2016 were considered. The same procedure was applied at the surgical unit, and care was taken not to count a file twice.
At the YMH, the same procedure was followed as at the DGH, which consisted of counting and recording the trauma cases, then counting and extracting data from TBI cases into CRFs.
Finally, at the LHD, which is noted to receive the highest number of trauma cases in the Littoral Region or Cameroon as a whole, data collection was limited to those available from the registers at the emergency department, because of the incoherent manner of data storage, and included age, sex, profession, cause and mechanism of injury, and TBI severity. As a consequence, detailed data on clinical characteristics and imaging could not be retrieved from this site. All the registers at the emergency unit between 2016 and 2020 were considered; however, the months of January to April 2016 were missing because registers could not be found.

Discharge status and outcome
Survival status on discharge, discharge destination, if the patient was DAMA, and calculated LOS were recorded. The Glasgow Outcome Scale-Extended (GOSE) was not recorded in patient files at discharge; therefore, to record the outcome, the report at discharge on the patient's discharge files were read. The outcome on discharge was classified as death, VS, mental or physical disability, and good recovery. Good recovery was considered present if no complaints were reported at the time of discharge and all the vitals were normal.

Statistical analysis
Required data were extracted from patient files into dedicated CRFs and checked for any errors. All forms were given unique codes and the information entered into a CSPro 7.6 data mask built by the statistician. Continuous variables are reported as medians with 25th and 75th percentiles and as means and standard deviations (SDs). Categorical variables are described as frequencies and percentages. TBI prevalence was calculated by dividing the total number of TBI cases registered within the 5-year period by the total number of trauma cases within the same period and multiplied by 100. Comparisons between two categorical variables were done using the chi-square test or Fisher's exact test, where appropriate. p values <0.05 were considered statistically significant. Analysis of data was performed using RStudio software (version 1.4.11; Posit, Boston, MA).

Ethical clearance and administrative authorizations
Ethical clearance for the study was obtained from the institutional review board of the Faculty of Health Sciences, University of Buea (Reference No.: 1238-08). Administrative authorizations were obtained from all three referral health facilities where the study was conducted: Yaoundé Military Hospital, Douala General Hospital, and the Laquantinie Hospital of Douala. The need for informed consent was waived because this was a retrospective study on routinely collected data.
Prevalence of traumatic brain injury among trauma cases across the months and years between 2016 and 2020 Prevalence of TBI in the study period was 34% (Fig. 1). Between 2016 and 2020, the DHG recorded the highest TBI prevalence (37.7%), followed by the LHD (34.6%) and YMH (26.8%; Supplementary Fig. S1). Prevalence of TBI significantly increased from 31.8% in 2016 to 38.3% in 2020 ( p < 0.001; Supplementary Fig. S2). Results were consistent across centers, with the greatest increase in the YMH ( Supplementary Fig. S3). Consistent with an increase in prevalence rates, the number of cases of TBI also relatively increased across the years, albeit showing a slight drop in 2018 and 2020 (915 TBI cases in 2016, 1406 in 2020), as shown in Figure 2. Although some variability over the years of the study existed in the number of TBI cases across the months of the year, the highest number of TBI cases was consistently found toward the end of the year (Fig. 3).

Clinical presentation
More detailed data on clinical and imaging characteristics were available for data collected at the DGH and YMH (2178) only. Median GCS was 14.0 (3.0-15.0). Loss of consciousness and headache were the two most common manifestations of TBI (75.3% and 39.0%, respectively; Table 2). Most TBI cases arrived at the reference hospital in less than a day (81%; 1599 of 1980), but 22 (1.7%) arrived over a month after injury. For those who arrived at the treatment center in less than a day, most (87%; 1397) arrived between <1 and 8 h (Supplementary Table S1). The major transportation means for the TBI cases was taxi/private vehicle (82.8%; 1639), followed by ambulances in 13.5% (267) of cases, and motorcycles were used in 36 (1.8%) cases (Supplementary Fig. S3). Most patients had stable vital signs on admission (Table 2). Median heart rate of TBI patients on arrival at the hospital was 84 (34.0, 198) beats per minute, and the majority had a normal temperature (90.0%; 1580 of 1756). Hypotension was present in 33% and in 31% of patients with moderateto-severe TBI, respectively.
Causes and mechanism of injury among traumatic brain injury cases The three most common causes of TBI recorded in the study were road traffic incidents (RTIs; 75% [4686]), assaults (13.2%; 825), and falls (9.3%; 581). Other causes included sports and industrial/occupational accidents ( Table 4).
Specific age or professional groups were more likely to have TBI incidence. RTIs were the most common cause in young adults ages 15-45 (77%; 3592) years. Male sex (81%) was significantly ( p < 0.001) more  exposed to RTIs than females (19%). Professional bike riders and unemployed persons were the professions more likely to have an RTI (21% and 15%, respectively), as revealed in Table 5. On the other hand, falls were the most frequent cause of TBI in those under 15 years of age and in older persons ( ‡60). Falls were more frequent in males (68%) compared to females (32%), and students (27%) were more likely to have a TBI attributable to a fall than any other professional group (Supplementary Table S2). Assault was significantly ( p < 0.001) associated with TBI in the 15-45 (89%) age group and the unemployed (24%; p < 0.001) whereas no significant difference between males and females was observed (Supplementary  Table S3).

Discharge destination and status
Most patients were discharged to home (71.6%; 1559 of 2178). A total of 341 (19.6%) patients were discharged against medical advice, of whom 282 (82.7%) were because of financial limitations to continue treatment as well as the preference to follow traditional treatment in a further 11 (0.3%). Among those who left against medical advice, 11% (38 of 341) had severe TBI whereas 31% (105/341) had moderate TBI. Only 6.4% (140) were recommended rehabilitation services, such as physiotherapy, psychiatry, and psychosocial counseling. Overall mortality was 10.3% (225 of 2178), of whom 23 died on arrival and 202 in the hospital. Mortality rates were higher after severe TBI (51.5%; 187 of 363) compared to moderate (6.6%; 31 of 469) and mild     (Table 6).

Discussion
Our study aimed to determine the prevalence and causes of TBI in Cameroon, through a 5-year retrospective study in three referral hospitals in urban Douala and Yaoundé. Hospital files and registers provided insight on the prevalence and causes of TBI, but also highlighted the challenges involved in observational studies in low-resource settings and illustrated the impact of financial constraints on care provision. Prevalence of TBI observed in the study (34%) is like that obtained by McKinglay and colleagues 36 in New Zealand and Onwuchekwa and Echem 15 in a West African country (Nigeria), who reported prevalence rates of 30% and 30.9%, respectively. However, the studies of Tesfaw and colleagues 37 and Walle and colleagues, 38 in Ethiopia, reported higher prevalence rates of 39.7% and 40.4%, respectively. On the contrary, other studies have reported lower prevalence rates: Abate and colleagues reported a pooled prevalence of 20% in Ethiopia. 28 Qureshi and colleagues 26 reported a prevalence rate of 19% for the capital city of Lilongwe in Malawi, and Webster and colleagues 39 reported a prevalence of 24% in South Africa. The difference in prevalence rates may be explained by differences in study design and sample sizes, where cross-sectional studies on lower sample sizes and a very short duration of study ranging from 1 to 2 months were utilized. In addition, lower prevalence rates may partly be because the studies were more than a decade ago, and since then TBI incidence has increased in Africa, and differences in the population density. 29,30 In contrast, the lower prevalence in South Africa may reflect a better infrastructural development and better road networks compared to other SSA countries.
Findings of this study demonstrate how the number of TBI cases varies considerably with the months of a year, with higher numbers of TBI cases toward the end of the year. The 5-year duration and larger sample size of this multi-center study, involving three referral hospitals with up to 18,151 trauma cases, allowed for more precise estimates and permitted the exploration of trends across the months of the years.
Observations from the study found that prevalence of TBI increased in Yaoundé and Douala-Cameroon from 2016 to 2020 by an absolute value of 6.5%. Accordingly, the numbers of TBI cases generally increased in these two cosmopolitan cities from 2016 to 2020. This corroborates reports in the literature showing an increase in global incidence of TBI with particular interest in LMICs, observing 3 times more new cases of TBI than HICs. 22,41 The slight drop in the actual number of cases observed in 2018 and 2020 was also reflected in the total number of trauma cases and can be explained by the electoral and post-electoral atmosphere in 2018 and the Covid-19 confinement in 2020, which may have considerably reduced the movement of persons. The substantial increases in number of TBI cases across the years highlight the increasing burden of TBI in the resource-limited countries in which a majority of the population live in poverty, have no health insurance, and would not have finances to undergo adequate care after TBI.
Lack of general resources is reflected in the fact that three quarters of patients (83%) in this study used private transport to reach treatment centers, given that there are few or no emergency transport services. This greatly delays the arrival of TBI patients to the trauma centers and increases the risk for secondary insults. With emergency transport services, patients can be transferred in a more stable condition and, importantly, emergency departments can be notified so that they can prepare for their arrival, which is not the case with private transport. 42 RTIs, assaults, and falls were the three most common causes for TBI in Cameroon, in line with reports in Tanzania, 43 Malawi,12 Nigeria, 44 Ghana, 45 Egypt, 46 Uganda, 47,48 China, 49 Angola, 50 and Cameroon 51 and in a multi-center study in selected African and Middle East countries. 17 The high rate of RTIs in LMICs differs from HICs, [52][53][54] where falls constitute the most common cause of TBI. This difference is likely related to better road infrastructure and stricter traffic safety regulations, which limit the incidence of RTIs, compared to African countries where poor road networks are a common reality. 62 Moreover, most African countries, because of the lack of resources, import secondhand cars, whose failure rate is high, and this can contribute to traffic incidents. Also, the use of seatbelts and/or motorcycle helmets are not common practice, although present in the legislations of most African countries (94%). 55 Besides these reasons, the population of Africa is fast growing alongside urbanization, which includes an expansion in motorization with little or no safety considerations in terms of road design and proper implementation of highway codes and safety practices. 55 Factors associated with the likelihood of RTIs included being male (81%), having bike riding as a profession (21%), and unemployment (15%).
More than half of RTIs (60.2%) involved a motorcycle. However, the injury mechanism was not reported in most cases (43.3%), highlighting another big problem on effective documentation and recordkeeping faced by LMICs. The high involvement of motorcycles in RTIs could be explained by the non-implementation of safety measures by users, lack of follow-up of road safety procedures by authorities, increasing unemployment, and the younger population seeking jobs, therefore increasing hazardous jobs. Further, insecurity in the two English-speaking regions of Cameroon in 2016 (Anglophone crisis) led to a rural exodus of youths into Douala and Yaoundé, who had as their main activity commercial bike riding, did not wear helmets, seldom had a driver's license and who were hence ignorant of the highway code, and uncontrolled alcohol consumption. 56 All these factors likely contribute to the high rate of RTIs in Cameroon and particularly to the involvement of motorcycles in most traffic incidents. Identification of the causes of RTIs with respect to age, sex, and profession could help in the development of preventive strategies based on characteristics of the population.
Although RTIs were the most common cause of TBI in the overall population, assaults were also common in the age group 15-45, but in contrast to other causes of injury, there was no difference between males and females, which is similar to reports by Kinscherf, 59 who reported that assaults were most likely to occur among adolescents and young adults. It is also consistent with the reports by Jeanneret and Sand 60 and the World Health Organization. 61 Assaults were associated with unemployment, in line with the studies of Osakwe and Umoh, 62 Outwater and colleagues 63 in Tanzania, the Governance Social Development Humanitarian Conflict, 64 and World Development 65 reports, which revealed that unemployment was linked to more violence/ assaults, especially in LMICs.
The length of hospital stay between 1 and 7 days in most of the cases is in line with the study of Tesfay 66 in Ethiopia, where most TBI patients had a hospital stay between 1 and 10 days. The proportion of patients considered to have good recovery (68.6%) is in line with the findings of Landes and colleagues 67 in Ethiopia and Eaton and colleagues in Malawi, 12 but the proportion of patients discharged in the VS in this study was higher (4.1%) than that reported in a study in Malawi (0.8%).
Overall, we found a mortality rate of 10.3% across all severities and 51.5% in severe TBI cases. The overall mortality rate is similar to that reported by an Ethiopian emergency center, 67 but differs from the 18% mortality reported by Clark and colleagues 17 in a multi-national study including LMICs that considered only neurosurgical cases. Higher mortality rates (30.7%) have been reported by the main national trauma center in Tanzania, 68 where the majority of trauma cases around the country converge. The mortality rate of severe TBI registered in this study (51.5%) is substantially higher than rates reported in HIC settings. Lu and colleagues 69 reported a mortality rate of 27% for patients with severe TBI in 1996, and the European CENTER-TBI study, collecting data from 2014 to 2017, reported a mortality rate of 27.8% (Maas, personal communication). Mortality rates for severe TBI in Cameroon therefore appear to be double the rates in HIC settings. Likely explanations include the lack of appropriate prehospital and post-acute care, limited resources, and financial constraints to obtain necessary healthcare.
A relatively high number of patients (27.4%) in this study did not undergo neuroimaging, and in 75%, financial limitation was advanced as a hindrance to perform the required exams. A total of 19.6% of cases were DAMA, of whom 83% had financial limitations to continue treatment. We note that the number of cases of DAMA in LMICs like Cameroon is likely an underestimation of the true financial burden of treatment after TBI given that a large number of persons live in poverty with no health insurance. In addition, some patients receive treatment, but are not permitted to leave the hospital thereafter until they settle the hospital bills. 70 This situation may adversely influence recovery and contribute to psychological distress in patients and their families. Further, there is a substantial risk of readmission and poor outcome among persons who leave the hospital against medical advice. 71 Paradoxically, the negative consequences of financial constraints, leading to DAMA, remain largely unreported or non-investigated in LMICs, where the burden of TBI is most felt. Although affordable healthcare is considered a basic human right, 72 in Cameroon over 60% of households cannot access appropriate healthcare because the cost is high. 73 Nde and colleagues 73 reported that *70% of Cameroonians spend out-of-pocket for their healthcare. To resolve this problem, the Ministry of Public Health in Cameroon started reflections in 2015 with the objective to implement a universal health coverage, 74,75 of which the pilot phase was expected to start in 2018, but, unfortunately, is yet to be implemented. 76 This delay renders it unlikely that the country can achieve the anticipated universal health coverage by 2035. 73 These delays, in combination with the sociopolitical and security threats that the country faces in recent years, suggest that the suffering inflicted on the population because of the inability to afford healthcare will likely rise considerably.
This study clearly illustrates the challenges in conducting observational research in resource-limited settings. First, files on the year 2016 were missing in one of the participating hospitals (DHG), and in another (LHD), we had to restrict data extraction to registers at the emergency department, prohibiting the extraction of detailed clinical and imaging information. Further, at this site, the files of January to April 2016 could not be retrieved. Second, when extracted, the data showed many missing values for various characteristics. Good medical practice entails detailed recordkeeping that is comprehensive, timely, and adequate. 77 The poor recordkeeping observed in Cameroon and other LMICs may be explained by the limited priority that is accorded to record management 80 and to the fact that more efforts seem to be concentrated on financial implications, of which several researchers have reiterated that hospital recordkeeping is ''more than just money'' given that every component of it is to be treated with utmost care. 81 LMICs still face many challenges with hospital recordkeeping, which could have adverse consequences and potentially reduce the value of healthcare and greatly affect the opportunities for and yield of research. 77 Several studies indicate poor funding, inadequate computer and other information communication technology devices, poor skill in computing, harsh environmental conditions, and the lack of a preservation and conservation policy as key challenges that hinder adequate recordkeeping in developing countries. 78,79 The difficulties linked to recordkeeping revealed in this study highlight the need for health systems in LMICs to invest resources to ensure that good recordkeeping is practiced. Electronic medical record systems practiced in developed countries are still making their way into most developing countries and are yet to make their effective entry in Cameroon.

Strengths and limitations
This is the first study designed to retrospectively collect data on TBI on a large scale in Cameroon and SSA. A major strength of the study is the large data set collected over 5 years and included all age groups and professions. The results can inform healthcare policies to improve prevention and develop strategies to achieve best care services, aimed to improve the outcome for patients with TBI in Cameroon and the Sub-Saharan region. Despite the incomplete data retrieval as a result of the missing files, incomplete data entry and poor conservation of data leading to many missing values was identified as a limitation, probably reducing the statistical power or running the risk of biased estimates 82 ; nevertheless, the data obtained are robust. Among the other limitations in the data sought were the lack of data on long-term outcome and a structured approach to record outcome on discharge. Despite these limitations, the results are relevant from a public health perspective.

Conclusions and Implications
Prevalence of TBI in Cameroon, like other parts of Africa, is high and has increased by 6.5% from 2016 to 2020. The number of TBI cases per year in all hospitals relatively increased from 2016 to 2020. The main causes accounting for brain injury in Cameroon are RTIs, assaults, and falls. Mortality in patients with severe TBI was disproportionately high, unlike in HIC settings. We further demonstrate how financial constraints can result in disparities in care. Our experiences in data extraction illustrate problems specific to research in low-resource settings. Observations from the study would inform preventive actions, including healthcare and transport policies to reduce the incidence of TBI in Cameroon by developing and implementing adequate road safety policies and infrastructures. In addition, the implementation of a universal health insurance policy may improve hospital care and reduce the adverse effects of TBI among Cameroonians.

Acknowledgments
We acknowledge the administration and health personnel of the hospitals involved in the study, for facilitating access to the files and registers. Our gratitude also goes to the NIHR Global Health Research Group on Neurotrauma, Cambridge University (UK), for the technical support.

Funding Information
The study received no funding; however, the financial needs to the realization of the study came from the authors.  Table S1  Supplementary Table S2  Supplementary Table S3