A prospective analysis of risk factors for pediatric burn mortality at a tertiary burn center in North India

Burden of PBs and its association with socio-economic development status in 204 countries and territories, 1990-2019

BACKGROUND

Burden of pediatric burn (PB) varies globally, attributable to a spectrum of countries, medical condition, and Socio-demographic Index (SDI). We determined the trends and changes in the global burden of PB among children using Global Burden of Disease (GBD) data.

METHODS

Data were extracted from the GBD, offering an exhaustive overview of the age-standardized incidence, Disability-Adjusted Life Years (DALYs), and mortality rates of PBs from 2009-2019. We assess the data of the PB burden across 204 nations and territories, as well as to investigate the interplay between the SDI and a spectrum of burn-related sequelae, encompassing amputations and inhalation injuries.

RESULTS

The age-standardized incidence, DALYs, and mortality rates for PBs were calculated at 135.25 (95 % UI: 205.27-89.44), 1.01 (95 % UI: 1.37-0.72), and 93.16 (95 % UI: 67.42-124.21), respectively. A slight predominance in the PB burden was observed among females relative to males. An inverse correlation between SDI and burn incidence was observed for SDI values below 0.4, which shifted to a positive correlation for mortality and DALY rates within the 0.4-0.6 range, followed by a plateau. Above an SDI of 0.4, a negative correlation with mortality and DALY was discerned. The highest global incidence was reported in Latin America, whereas Oceania (excluding Australia and New Zealand) exhibited the highest mortality and DALY rates. Severe burns were linked to the most substantial burden, succeeded by inhalation injuries and amputations.

CONCLUSION

The PB burden, as indicated by age-standardized incidence, DALYs, and mortality rates, is modulated by SDI and gender, with pronounced disparities in epidemiological patterns between Oceania and Australasia, despite their similar socio-economic categorization. There is an imperative to intensify burn prevention strategies in middle- and high-income countries and to augment treatment capabilities in low- and middle-income nations. Emphasis on the management of severe burns is paramount for diminishing the overall PB burden, with a subsequent imperative to address inhalation injuries and amputations. Heightened vigilance in burn care and prevention is imperative, particularly in Latin America, Africa, and Oceania, to ameliorate the impact of these injuries on vulnerable pediatric cohorts.

Country economic status is strongly associated with burn survival - validation of the (modified) ABSI

BACKGROUND

Predicting burn-related mortality is vital for family counseling, triage, and resource allocation. Several of the burn-specific mortality prediction scores have been developed, including the Abbreviated Burn Severity Index (ABSI) in 1982. However, these scores are not tested for accuracy to support contemporary estimates of the global burden of burn injury. This study compares burn mortality across countries with varying economic levels, as indicated by the Human Development Index (HDI), to assess if a modified ABSI (mABSI) offers enhanced predictive accuracy.

METHODS

A retrospective study was performed, including over 90,000 patients from seven sources in five continents, including two burn registries and five referral burn centers. Data from 2015 to 2019 were collected, including age, gender, presence of inhalation injury, full-thickness burn, percentage of total body surface area, and outcome. The participating countries were classified based on the HDI and mortality was predicted using both the original and the modified ABSI.

RESULTS

After removal of incomplete data, 74,460 sets remained for the analysis. Significant variations in population demographics, sample sizes, total body surface area (TBSA), and age distributions across the studied regions were noted. The modified ABSI demonstrated a smaller deviation from the 95% CI of the true survival probability than the original ABSI in countries with a very high or high HDI, indicating improved accuracy here. In these countries, the original ABSI overestimates mortality. Conversely, in countries with a middle or low HDI, the original ABSI remains more accurate, reflecting the significantly greater burn related mortality in countries with a low HDI.

CONCLUSION

In burn patients, the probability of survival remains highly dependent on the level of development of a country. Our results support the use of the modified ABSI in countries with a (very) high HDI, yet in resource constraint settings, the original ABSI seems to provide more accurate predictions. These findings underscore the need for adaptive models that take into account socioeconomic variables, potentially guiding health policy adjustments and emphasizing the necessity of resource allocation and training in lower HDI countries. Such adaptations could enhance clinical outcomes and reduce disparities in burn care effectiveness globally.

Survival Status and Predictors of Mortality Among Pediatrics Burn Victims Admitted to Burn Centers of Addis Ababa Public Hospitals, Ethiopia: A Retrospective Cohort Study

Background. Burn is a major public health problem in pediatric populations worldwide. This study aimed to determine the survival status and predictors of mortality among pediatric burn victims admitted to burn centers in Ethiopia. Methods. A retrospective cohort study was conducted on the patient charts of 412 pediatric patients with burn injuries at burn centers in Addis Ababa from the 1st of January 2016 to the 30th of December 2019. Data was entered into the Epi-Data manager. Then, the data was exported to STATA V-14 for cleaning and analysis. For the analysis, the proportional hazard model was used. After the model fitness test, variables with a P-value of <.25 in the bivariate analysis were fitted to the multivariate analysis. Finally, statistical significance was decided at a P-value of <.05, and the hazard ratio was used to determine the strength of the association. Result. The study reported an overall incidence rate of 2.4 per 1000 child days. Additionally, it revealed that the median hospital length of stay was 25.00 days (95% CI: 21.57, 28.45). During the follow-up period, 8.25% of deaths occurred among pediatric patients with burn injuries. Specifically, having a full-thickness burn (adjusted hazard ratio [AHR] 2.51, 95% CI: 1.12, 5.62) and neck burn (AHR 2.82, 95% CI: 1.04, 7.68) were identified as significant predictors contributing to increased mortality among burn-injured pediatric individuals. Conclusion. The study highlighted significant mortality rates among pediatric patients suffering from burn injuries. Based on the findings a full-thickness burn injury and burns in the neck area are independent predictors of mortality in pediatric burn patients. Based on the identified predictors of mortality in pediatric burn patients, clinicians should prioritize early recognition, prompt intervention, multidisciplinary management, vigilant monitoring, and preventive strategies to optimize outcomes and reduce mortality rates in this vulnerable population.

Serum procalcitonin and C-reactive protein as indices of early sepsis and mortality in North Indian pediatric burn injuries: a prospective evaluation and literature review

BACKGROUND

Delays in diagnosing sepsis in children afflicted with thermal injuries can result in high morbidity and mortality. Our study evaluated the role of the biomarkers Procalcitonin (PCT) and C-reactive protein (CRP) as predictors of early sepsis and mortality, respectively, in this group of patients.

METHODS

This was a prospective evaluation of 90 pediatric burn cases treated at a tertiary care burn center in Northern India. Patients, aged 1-16 years, presenting within 24 hours of being burned, with >10% body surface area of burn injury were included in the study. Levels of PCT and CRP were measured on days 1, 3, 5, and 7. Patients were followed until discharge, 30th post-burn day, or death, whichever occurred first.

RESULTS

Sepsis was clinically present in 49 of 90 (54.4%) cases with a median 30% total body surface area (TBSA) of burns. Mortality was seen in 31 of 90 (34.4%) cases with a median of 35% TBSA burns. High PCT and CRP were seen in the sepsis group, particularly on days 3, 5, and 7. PCT was also significantly higher in the mortality group (days 1 and 3).

CONCLUSIONS

While PCT was a good early predictor of sepsis and mortality in children with burns, CRP was reliable as a predictor of sepsis only. Both markers, however, can serve as adjuncts to culture sensitivity reports for diagnosing early onset sepsis and initiation of antibiotic therapy in appropriate patients.

Analysis of anatomic location of burns inpatients in China from 2009 to 2018

BACKGROUND

Burns cause serious physical and psychological harm to patients, placing a heavy burden on the global healthcare system. Our previous study detailed the epidemiological characteristics of burn injuries in Chinese inpatients from 2009 to 2018. Interestingly, the anatomic locations of burn injuries vary by gender, age, provinces, and outcomes among different causes. Therefore, this current study aims to analyze the characteristics of burn injuries in inpatients with various burn sites by collecting data in China from 2009 to 2018. This analysis will inform future healthcare system decisions and provide effective strategies.

METHODS

Burns inpatients from 196 hospitals across 31 provinces in China were included in the study, covering the period from 2009 to 2018. The data collected encompassed information on gender, age, etiology, regions, clinical outcomes, and anatomical locations of the injuries. Data analysis was conducted using Microsoft Excel 2007.

RESULTS

From 2009 to 2018, a total of 333,995 burns inpatients were recorded. The most vulnerable parts to burns were multiple burn sites (230,090, 68.89%). Women were more susceptible to lower limb burns (15,608, 14%), while men were more prone to eye injuries (8,387, 3.37%) and hand burns (6,119, 2.75%). The age group of 0-10 years was the most vulnerable to burns across all body areas, including internal organs. In China, individuals aged 20-50 years were at a higher risk of head and neck burns compared to other age groups. The Han population showed increased vulnerability to eye injuries (2.12 times higher than minorities), respiratory tract issues (2.09 times higher than minorities), and trunk burns (1.83 times higher than minorities), while being less susceptible to internal organ injuries (0.23 times fewer than minorities) and lower limb burns (0.78 times fewer than minorities). The southwest region had the highest proportion of burns inpatients with burns affecting single body parts, whereas the eastern area had the highest rates of respiratory tract burns (0.85%) and multiple burn sites (80.64%). Scalding was identified as the most common cause of burns, while flame burns (769, 55.81%) and chemical burns (438, 47.35%) were the main causes of respiratory tract and internal organ injuries, respectively.

CONCLUSIONS

This study provides an initial description of characteristics of burns inpatients with various anatomic locations of burns in China over the past decade. Our findings will contribute to the most up-to-date clinical evidence database for healthcare planning and prevention initiatives in both China and other countries.

Epidemiology of Burn Injuries Among Adult Females in Southern Iran; A Retrospective Study from 2007 to 2022

Burn-by flame, flush, scald, electrical, and chemical types-accounts for 5%-12% of trauma injuries worldwide. In Iranian studies, females were the main victims of domestic burns with higher mortality and frequencies. This retrospective study evaluates the epidemiology and etiology of burn injuries in females aged 25-64 years between October 2007 and May 2022 in southern Iran. Demographics and burn etiology information were collected by questionnaires at admission. Univariate and multivariate regression analysis was used to determine the relationship between variables and burn mortality. Pearson's Chi-Square and One-way ANOVA tests were utilized to compare different burn etiologies. Of 3212 females with burn injuries, 1499 (46.6%) were included with a mean age of 38.5 ± 10.8 years. Flame (59.7%) and flush (28.9%) were significantly the most common injuries mechanism. Burn was most common in rural areas (53.9%) and indoor settings (62.1%) (P-value < .001). 77.9% of the population were under-diploma (P-value < .001), and 3.5% were divorced with higher burn-suicide attempts. The mean Total Body Surface Area (TBSA%) was 41.1 ± 28.3%, and the mean Length of Stay (LOS) was 14.5 ± 13.2 days with a 39.1% mortality rate. With univariate and multivariate analysis, TBSA%, indoor places, flame, flush, and urban living were risk factors for burn mortality. Briefly, flame in indoor settings is the most common type of burn injury affecting adult females with lower educational levels living in rural areas. Such epidemiological studies of burns in adult females may be helpful for health policymakers to develop burn prevention programs.

Pediatric Burns-Time to Collaborate Together

How to cite this article: Baalaaji M. Pediatric Burns-Time to Collaborate Together. Indian J Crit Care Med 2023;27(12):873-875.

Food Security as a Predictor of Global Pediatric Postburn Mortality

Food security (FS) is defined as access to sufficient and nutritious food. Children, especially those in low- and middle- income countries (LMICs), are disproportionately affected by low FS. We hypothesized high FS would be predictive of decreased pediatric postburn mortality in LMICs. Publicly-available, deidentified datasets were obtained from the World Health Organization's Global Burn Registry (GBR) and Economist Intelligence Unit's Global FS Index (GFSI). The GFSI calculates FS scores annually from intergovernmental organization data reviewed by a panel of experts. FS scores are reported on a 0 to 100 scale with 100 indicating the highest FS. Patients aged 0 to 19 yr were included; after linking GBR and GFSI datasets, countries with <100 burn patients were excluded. Data were analyzed with descriptive statistics and bivariate analyses. Multiple logistic regression controlling for confounders was used to quantify associations between mortality and FS score. Significance was set at P < 0.05. From 2016 to 2020, there were 2,246 cases including 259 deaths (11.5%) over nine countries. Those who died had a higher median age (7 [IQR 2, 15] vs 3 [2, 6] years, P < 0.001), higher proportion of females (48.6% vs 42.0%, P =0.048), and lower median FS score (55.7 [IQR 45.3, 58.2] vs 59.8 [IQR 46.7, 65.7], P < 0.001). Increasing FS score was associated with decreased odds of postburn mortality [multivariable odds ratio 0.78 (95% confidence interval 0.73 to 0.83), P < 0.001]. With the association between FS and mortality, international efforts to increase FS in LMICs may help improve pediatric burn patient survival.

Epidemiology of non-fatal burn injuries in children: evidence from Bangladesh Health and Injury Survey 2016

BACKGROUND

Burn is a major cause of childhood injury-related morbidity and mortality. Global estimates suggest that 90% of all cases occur in low-income and middle-income countries and over half of the disability-adjusted life-years are lost from fire-related burns in children. In Bangladesh, there is a scarcity of data on childhood burn injuries. The goal of the study was to describe the epidemiology of non-fatal burns in Bangladeshi children, including incidence estimates and identify high-risk groups.

METHODS

Bangladesh Health and Injury Survey 2016 was a large scale cross-sectional survey. The survey was conducted among 299 216 population utilising a multistage cluster sampling method. Among the 100 842 children, there were 437 non-fatal burn cases.

RESULTS

Among different injury mechanisms in children, burn was ranked fifth (7.4%). The overall yearly incidence rate (IR) of burns was 866.7 per 100 000 children (95% CI 785.6 to 947.8) in Bangladesh. The incidence was highest among 1-4 years old children (IR 2028.3, 95% CI 1761.1 to 2334.7) and had a 3.5 times higher risk of burns compared with the 15-17 years age group. Females had a much higher IR of non-fatal burns than males between the ages of 10-15 years (1655.2 vs 482.2). About 70% of burns occurred in rural areas. Hot liquid (44.7%), flames (32.5%) and hot objects (20.7%) were identified as the main causes of burns. The kitchen (60.9%), yards (20.8%) and bedroom and living room (10.5%) were the three most common places for burns. According to the study, 34.8% of burn incidences occurred between the hours of 7:00 and 10:00.

CONCLUSION

Children in Bangladesh suffer from a high rate of non-fatal burns. The high-risk category was identified as preschool-aged boys and adolescent girls. The majority of the incidents occurred in the morning and inside the kitchen. These findings will help raise awareness and create intervention measures to reduce the high incidence of non-fatal childhood burns in Bangladesh.

Analysis of risk factors of mortality for pediatric burned patients with inhalation injury and comparison of different treatment protocols

BACKGROUND

We present our approach of pediatric burned patients with the suspicion of inhalation injury.

METHODS

This retrospective study was conducted on children with the suspicion of inhalation injury admitted to our burn center from December 2009 to December 2019. We collected data on patient demographics, total burn surface area (TBSA), presence of inhalation injury, level of carboxyhemoglobin, grade of inhalation injury, duration of mechanical ventilation, reintubation rate, total length of hospital stay, and the mortality rate. We also reviewed the required treatment of patients with inhalation injury.

RESULTS

A total of sixty pediatric burn patients were suspected inhalation injury were included in this retrospective study. 40 pa-tients included in the study were male. Age average of the patients was 87.7 months. Total burned surface area average was 32%. 46 of these patients had inhalation injury. Patients with larger cutaneous burn and needed early intubation have a higher risk of inhalation injury. There was no significant relation between inhalation injury grades and mortality and treatment protocols. Higher levels of car-boxyhemoglobin and larger TBSA are the risk factors for mortality at univariate analysis. Pediatric patient with inhalation injury whose TBSA is higher than 47.5% has a 5 times higher risk of mortality at multivariate analysis.

CONCLUSION

This study demonstrated that TBSA is the risk factor that independently affects the mortality in pediatric patients with inhalation injury. Among the patients with higher than 47.5% burn surface area, the mortality rate rises 5 times.

High Level of Multidrug-Resistant Gram-Negative Pathogens Causing Burn Wound Infections in Hospitalized Children in Dar es Salaam, Tanzania

Background

Bacterial infection remains the most common cause of morbidity and mortality in pediatric patients with burn wounds. The increase in infection and multidrug-resistant (MDR) pathogens necessitates a periodic review of antimicrobial susceptibility patterns in the burn units. The study aimed to determine the magnitude of multidrug-resistant Gram-negative (MDRGN) bacteria in children with burn wound infections and describe the resistance patterns in the tertiary and regional hospitals in Dar es Salaam, Tanzania.

Materials and Methods

The study was a hospital-based cross-sectional study design conducted between May 2017 and February 2018. Bacterial isolates from 103 wound swabs of pediatric patients with burn wounds were identified using conventional methods and API 20E. The antimicrobial susceptibility pattern was determined by the Kirby-Bauer disc diffusion method. Data were analyzed using Statistical Package for Social Science (SPSS) version 23.0.

Results

A total of 136 pathogenic Gram-negative organisms were isolated from burn wound infections in pediatric patients. The most isolated Gram-negative bacterium was Pseudomonas aeruginosa (39.0%), followed by Acinetobacter spp. (28.7%) and Klebsiella spp. (16.2%). MDRGN strains made up 80.1% of all Gram-negative isolates. All (100%) Klebsiella spp. and E. coli were MDR, while 69.2% and 79.2% of Acinetobacter spp. and P. aeruginosa, respectively, displayed MDR strains. We observed high levels of resistance to commonly prescribed antibiotics. Among P. aeruginosa isolates, highest resistance (81.8%) was seen toward meropenem and piperacillin, 79.5% of Acinetobacter spp. showed resistance to aztreonam, while 93-100% of Klebsiella spp and E. coli displayed resistance to amoxyclavulanic acid, ceftriaxone, and ceftazidime. The proportion of extended-spectrum beta-lactamase producers among Enterobacteriaceae was 78.6%. There was a significant higher rate of infection with MDRGN organisms in pediatric patients with a higher percentage of total burn surface area (TBSA) than patients with lower TBSA (p = 0.016).

Conclusions

P. aeruginosa, Acinetobacter spp., and Klebsiella spp. are the common Gram-negative pathogens causing burn wound infections in hospitalized pediatric patients in our setting. A high proportion of these organisms were multidrug resistant. The findings appeal for regular antimicrobial resistance surveillance in burn wound infection to inform empirical therapy.

Exercise combined with trimetazidine improves anti-fatal stress capacity through enhancing autophagy and heat shock protein 70 of myocardium in mice

Background: Anti-stress capacity is important to resist the occurrence of adverse events. To observe the effects of exercise, trimetazidine alone or combined on the anti-stress capacity of mice, and further explore its potential mechanism. Methods: Forty-four C57BL/6 male mice aged 8 weeks were randomly divided into four groups (n=11 for each group): control group (group C), exercise group (group E), trimetazidine group (group T), exercise combined with trimetazidine group (group TE). After the intervention, each group was randomly subdivided into the exhaustive exercise (EE, n=6) and the non-EE (n=5) subgroups. The mice in the EE-subgroup underwent EE. Mice were sacrificed 12 hours later after EE. The myocardial ultrastructure and autophagosomes were observed under an electron microscope. The expression of autophagy-related proteins: BNIP3, LC3-II, and P62 were analyzed and the heat shock protein 70 mRNA transcription and protein expression were also investigated. Results: Exercise or trimetazidine increased the expression of BNIP3, LC3-II, and heat shock protein 70, decreased the expression of P62 pre- and post-EE while the combination has the synergistic effect. Conclusion: Exercise and trimetazidine, alone or combined enhanced the anti-stress capacity of mice significantly. The underlying mechanism may be associated with the promotion of autography and the expression of heat shock protein 70.

Comparison of prognostic models for burn patients: A retrospective nationwide registry study

BACKGROUND

Prognostic burn index (PBI) is a unique model utilized to predict mortality of burn patients in Japan. In contrast, other prediction models are rarely used in Japan, and their accuracy and predictive value are unknown. The present study aimed to compare commonly used burn prediction models and determine the appropriate model for mortality prediction in Japanese burn patients.

METHODS

Japanese burn patients registered in the nationwide burn registry of Japanese Society for Burn Injury between April 1, 2011 and March 31, 2019 were reviewed retrospectively. The prognostic performance of PBI was compared with Baux score, revised Baux score, abbreviated burn severity index (ABSI), Ryan score and Belgian outcome in burn injury score (BOBI). The primary outcome was in-hospital mortality.

RESULTS

The study included 7911 acute burn patients. The overall mortality rate was 10.7%, the median age was 52 (interquartile range, 26-72) years, and the median % total body surface area was 7% (interquartile range, 3%-17%). The areas under the receiver operating characteristic curve for PBI, Baux score, ABSI, revised Baux score, Ryan score, and BOBI were 0.940 (95% confidence interval [CI]: 0.931-0.948), 0.943 (95% CI: 0.934-0.951; p=0.002), 0.945 (95% CI: 0.937-0.953; p=0.058), 0.946 (95% CI: 0.937-0.953; p=0.002), 0.859 (95% CI: 0.846-0.870; p<0.001), and 0.896 (95% CI: 0.885-0.905; p<0.001), respectively.

CONCLUSION

Although the performance of PBI was good, it was not superior to the Baux score, revised Baux score, and ABSI. These three scores have a high prognostic accuracy. Hence, they are considered as alternative burn prognostic scores in Japan. The Baux score was an optimal prognostic model for patients with burns in Japan.

Trimetazidine combined with exercise improves exercise capacity and anti-fatal stress ability through enhancing mitochondrial quality control

AIMS

To explore the effects of trimetazidine combined with exercise on EC and anti-fatal stress ability, and illustrate the underlying mechanism.

METHODS

C57BL/6 mice were randomly assigned to four groups (n = 11 in each group): the control, exercise, trimetazidine and trimetazidine + exercise (TE) groups. Mice were accordingly given saline (ig), Aerobic exercise (AE), trimetazidine (ig), or a combination of trimetazidine (ig) and AE for five weeks. After the intervention, each group was randomly subdivided into rest and exhaustive exercise (EE) subgroups. The mice in the control-EE and TE-EE subgroups underwent fatal stress experiments. EC and anti-fatal stress ability were assessed respectively. Mitochondrial quality control (MQC) in skeletal muscle were measured at the protein level and the organelle level.

KEY FINDINGS

A significantly increased exhaustive swimming time was observed in exercise (39.10 ± 12.58 min vs 14.18 ± 4.37 min), trimetazidine (33.73 ± 8.45 min vs 14.18 ± 4.37 min) and TE groups (73.78 ± 18.95 min vs 14.18 ± 4.37 min) compared with that in the control group, and a synergistic effect was detected (P < 0.05). Fatal stress experiments successfully induced skeletal muscle damage, including increased creatine kinase activity, myofibrosis, and impaired antioxidative enzyme system, all those were significantly alleviated by trimetazidine supplementation combined with AE precondition (P < 0.05). Meanwhile, AE and trimetazidine alone or combined, significantly enhanced the MQC in normal mice by activating mitochondrial biogenesis, dynamics and mitophagy, and that in mice underwent fatal stress stimulus (P < 0.05).

SIGNIFICANCE

This study for the first time found that trimetazidine and AE have synergistic effects on improving EC. Moreover, the combination of both interventions enhances anti-fatal stress ability. Enhancing MQC may be a key mechanism of AE combined with trimetazidine that improves EC and anti-fatal stress ability.

Epidemiologic and clinical characteristics of severe burn patients: results of a retrospective multicenter study in China, 2011-2015

Background

Severe burns injury is a serious pathology, leading to teratogenicity and significant mortality, and it also has a long-term social impact. The aim of this article is to describe the hospitalized population with severe burns injuries in eight burn centers in China between 2011 and 2015 and to suggest future preventive strategies.

Methods

This 5-year retrospective review included all patients with severe burns in a database at eight institutions. The data collected included gender, age, month distribution, etiology, location, presence of inhalation injury, total burn surface area, depth of the burn, the length of hospitalization, and mortality. SPSS 19.0 software was used to analyze the data.

Results

A total of 1126 patients were included: 803 (71.3%) male patients and 323 (28.7%) female patients. Scalds were the most common cause of burns (476, 42.27%), followed by fire (457, 40.59%). The extremities were the most frequently affected areas, followed by the trunk. The median length of hospitalization was 30 (15, 52) days. The overall mortality rate was 14.21%.

Conclusions

Although medical centers have devoted intensive resources to improving the survival rates of burn patients, expenditures for prevention and education programs are minimal. Our findings suggest that more attention should be paid to the importance of prevention and the reduction of injury severity. This study may contribute to the establishment of a nationwide burn database and the elaboration of strategies to prevent severe burns injury.