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Violent trauma as an indirect impact of the COVID-19 pandemic: A systematic review of hospital reported trauma

Introduction The COVID-19 pandemic has exacerbated many social conditions associated with violence. The objective of this systematic review was to examine trends in hospital reported violent trauma associated with the pandemic. Methods Databases were searched in using terms “trauma” or “violence” and “COVID-19,” yielding 4,473 records (2,194 de-duplicated). Exclusion criteria included non-hospital based studies and studies not reporting on violent trauma. 44 studies were included in the final review. Results Most studies reported no change in violent trauma incidence. Studies predominately assessed trends with violent trauma as a proportion of all trauma. All studies demonstrating an increase in violent trauma were located in the United States. Conclusions A disproportionate rise in violence has been reported within the US. However, most studies examined violent trauma as a proportion of all trauma; results may reflect relative changes from lockdowns. Future studies should examine rates of violent trauma to provide additional context.

The Sars-Cov-2 virus has had a tremendous impact upon every healthcare system and society in the world since its discovery in the human population in December 2019. 1 The virus has since pervaded countries throughout the world, with ubiquitous impacts upon known social determinants of health, including financial insecurity, housing instability, and employment. 2e4 In addition to these stressors, lockdowns and social distancing mandates have contributed to a general worsening of population-level mental health. 5 Overall, these impacts, in addition to direct viral morbidity and mortality, have disproportionately impacted low-income communities. 6,7 Inequities in many of these same social factors are also associated with violent trauma. 8 Violence-related trauma has been associated with several community-level and individual factors, including education and employment opportunities, neighborhood level of social disadvantage, financial insecurity, proximity of liquor stores, and social isolation. 9,10 To this end, many interventions to prevent violent trauma recidivism address these social factors. 11 The World Health Organization reported in 2010 that trauma deaths total over 5.8 million annually, or approximately 10% of the annual deaths worldwide. 12 Of these, approximately one in three are violence-related. 12 These deaths are disproportionately experienced among individuals living in lower income communities. Simultaneously in 2020, these same communities experienced a disproportionate burden of COVID-19 cases, 7,13 including of the 1.7 million total deaths worldwide. 14 The COVID-19 pandemic constitutes a potential increase in the pre-disposing factors underlying the increase of violence, as well as a reduction in traditional mitigating factors and social supports. Given the increased expectations of social distancing and potential for exacerbation of social isolation, a factor known to be associated with violent trauma incidence, 9,15,16 it was expected that the COVID-19 pandemic and violence epidemic would converge. The objective of this study was to systematically review the literature in order to explore trends in community violence over the past year.
The following databases were searched on December 7, 2020: CINHAL, EMBASE, PubMed, PsychInfo, Scopus, and Web of Science, yielding a total of 4,473 records. No date limit was applied to these searches. Removal of overlapping records yielded a total of 2,194 records, for which the titles and abstracts were screened independently by two authors (KB and EH). Exclusion criteria consisted of articles not written in English, articles which did not assess violence rates, case reports, commentaries, systematic reviews, meta-analyses, and unpublished work (i.e., gray literature). Records which were not excluded by both reviewers were retained for full article review. A total of 226 records were then reviewed for inclusion by two authors (KB and EH). Records were removed based on the previous criteria. In order to limit the participant selection bias that may have occurred among population-based surveys, records were excluded if data were not reported based on hospital electronic health records or trauma registries. A total of 44 records were included in the final analysis. See Fig. 1.
Records were analyzed using a pre-developed spreadsheet to capture data on department of analysis, method of statistical assessment (proportion versus rate data, wherein proportion refers to the proportion of violent trauma relative to all trauma cases, versus rate of violent trauma cases per week/month/year data), direction of statistical change in trauma data (increase, decrease, no change, or not assessed), percentages/rates of violent trauma during the study and reference periods, p-value of significance (significance level was considered with a < 0.05), study and reference time periods, duration of study time period, study location, patient population status (urban or rural), and study population (all patients, adults, or pediatric cases). Statistical assessments were only included if the authors explicitly examined changes in violence incidence between the study and reference periods. Therefore, pvalues calculated for chi-square tests for change in all mechanisms of injury were not included, unless follow up testing with Bonferroni corrections were applied. The study's specific definition of violent trauma was also captured (e.g., domestic violence, assaults, stab wounds, etc.). The Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines were followed (see supplementary information).

Results
Of the 44 records included in this study, only 28 included an assessment of the change in proportion or rate of community violence incidence during the COVID-19 pandemic to date. Of these, half noted no change as compared to pre-pandemic times (n ¼ 14). The majority of studies (n ¼ 34) included were based out of hospitals located in high-income countries (defined by the World Bank). Eight studies noted an increase, ranging from an increase of 0.6% (1.1%e1.6%) 17 to more than 30% (Gosangi et al.: 12%e42%; Diamond et al.: 13%e47%) 18,19 while six noted a decrease in violent trauma, ranging from a decrease of 1% (2%e1%) 20 to 10% (23%e 13%). 21 An additional 15 studies provided data on the proportion or rate of violent trauma but did not explicitly analyze these changes statistically. Study duration ranged from 1 week to approximately 6 months (7e181 days), with an average length of 53 days. In addition to the overall outcome of changes in violent trauma incidence, studies were stratified and assessed according to department, method of analysis, location, and study duration (See Table 1).

Department
Most studies analyzed data from all departments in the hospital (n ¼ 24), i.e., from a formal institutional trauma registry or full   review of all encounters of patients in the hospital experiencing traumatic injury during the period of study. Department-specific studies were undertaken by Oral and Maxillary Facial Surgery (n ¼ 6), Orthopedic Surgery (n ¼ 5), Hand Surgery (n ¼ 4), Neurosurgery (n ¼ 2), Radiology (n ¼ 2), and General Surgery (n ¼ 1). Data did not show associations between department and outcome of changes in incidence of intentional injury, nor between department and study duration.

Method of study
Studies primarily assessed changes in violent trauma with these data captured as a proportion (84%, n ¼ 27) rather than as a rate (16%, n ¼ 5). Of the five studies which assessed trends in violent trauma using rate data, three of which found no change in incidence of violent trauma. 22e24 Morris and colleagues found a statistically significant decrease in violent trauma incidence (assaults decreased by half from approximately 400 during the month of April in 2018 and 2019 to 197 in 2020; gunshot injuries similarly decreased from 32 in 2018, 20 in 2019, to only 3 during the month of April in 2020) 25 ; Benazzo and colleagues did not statistically assess changes in rate. 26 Data did not show any association between analysis method and duration of study. All eight studies that reported an increase in violent trauma incidence examined data as a proportion, 17e19,27e31 and five of the six studies demonstrating a decrease utilized proportion data. 20,21,25,32e34 Magnitude of change in the proportion of violent trauma are shown in Fig. 2, for figures that assessed these data statistically and found any change.

Location
Rural-based studies accounted for two of the 44 records included in this systematic review. Neither study assessed changes in violent trauma statistically. 35,36 The majority of studies were based in urban locations, with heavy bias towards high-income countries, including the United States (n ¼ 14), 17e19,22,27e33,37e39 Australia (n ¼ 2), 23,34 and Western Europe (n ¼ 18). 20,21,24,26,40e53 Records were examined visually via placement of study results onto a world map. All eight studies showing an increase in violence were based in the United States. See Fig. 3. Duration Though the studies included in this review captured data across slightly different time periods, all studies included in this review examined data during the Spring of 2020 (March and/or April), and the majority of studies (n ¼ 30) examined data with the COVID-19 reference period starting within one week of a regional or national lockdown or social distancing order. Two studies assessed data beginning in January (duration of 121 and 181 days), and four assessed data beginning in February (duration 41e119 days). All others began examining data in March (n ¼ 37) or April (n ¼ 1). In order to assess the impact of study duration upon results, records were limited to those that assessed changes in violent trauma statistically (n ¼ 28). These records were then stratified according to duration, in months.
All studies with an increase in violent trauma took place in the United States. In order to examine these data more closely, duration of studies in this specific region was then assessed. Two studies took place over one month, and both found an increase in violent trauma (assessed as proportion of all trauma cases). 19,31 Of the seven studies that examined data across two months (31e60 days; lowest duration in this category was 41 days 37 ), five noted increases in the proportion of violent trauma incidence. 17,18,28e30 The other two studies found no change. Of these two, one study was limited to examination of cases of pediatric non-accidental trauma. 37 Of the four remaining US-based studies, ranging from 71 to 181 days, three found no change in violent trauma 22,32,39 and one found increased incidence. 27 Among the nine studies that statistically examined changes in violent trauma (duration 13e90 days), only the longest study, Salzano and colleagues, noted a decrease in violent trauma. 21 Australia based studies accounted for two records, over 60 and 61 days, and demonstrated no change (examined as a rate) and a decrease (examined as proportion) in violent trauma, respectively. 23,34 Two studies examined data from South Africa: Morris and colleagues found that over 30 days there was a decrease in the rate of violent trauma incidence, 25 and Zsilavecz and colleagues found no change in the proportion of violent trauma over 69 days. 54

Discussion
Violent trauma has been characterized as the neglected disease of modern society, and its exact etiology remains poorly understood. 12 Some risk factors associated with experiencing such violence have been elucidated in the past, including social isolation, poverty, low educational access, poor mental health, and weapon accessibility. 15,55e57 Because of the complex interactions between these risk factors, effective evidence-based treatment modalities addressing violent trauma remains difficult. 12,58 Nevertheless, it is evident that the COVID-19 pandemic has led to a substantial increase in the social factors associated with intentional injury, and the intersectionality of these risk factors during the pandemic was hypothesized to be associated with a universal increase in violent trauma incidence. However, of the 28 studies which statistically assessed this topic (N ¼ 44 overall), results were not conclusive in supporting nor refuting this hypothesis: 15 studies showed no change, 8 showed an increase, and 5 showed a decrease.

Method of study
Nearly all of the studies included in this review assessed violent trauma data as a proportion of all trauma cases over the defined study period. This type of analysis would be expected to skew positive (i.e., higher propensity to report an increase in the proportion of violent trauma), for both population psychological and medical reasons. Specifically, emergent studies demonstrate a reduction in utilization of emergency department services overall, potentially reflective of reduced demand for services and/or reductions in seeking of needed care due to fears of Sars-Cov-2 infection during hospital treatment. 59 In addition or alternatively, less non-intentional trauma may have occurred (e.g., work-related accidents, motor vehicle accidents) as individuals worked from and stayed at home: increases in the population rate of intentional trauma related to the pandemic without any change in nonintentional traumas would inflate the proportion, relative to previous years. In contrast to this expectation, only 8 studies reported an increase in the proportion of violent trauma (3 reported a decrease; 13 reported no change). Overall, among the eight studies that found an increase in violent trauma, half reported data on other non-intentional trauma types. Specifically, two studies found a significant decrease in motor vehicle collisions, 28,30 one found a significant decrease in pedestrian versus automobile accidents (but no change in motor vehicle collisions), 29 and one found an overall decrease in unintentional trauma (but no specific declines within motor vehicle collisions/pedestrian accidents). 27 In contrast, of the three studies using proportion data which found a decrease in violent trauma, one found a similar decrease in motor vehicle collisions, 20 and one found no change 34 (the third did not report these data). 21 Overall, it is possible that traumatic injuries in general increased after a brief decline at the onset of the pandemic, but that this period lasted only 1e2 months, after which other types of traumatic injuries increased, and so such data were lost: the average duration for studies reporting an increase was 52.6 days, versus 68.3 days among studies reporting a decrease, and 55.6 days among studies reporting no change.
Notably, Philadelphia, a major urban city with high pre-COVID rates of violence and which was reported on by three studies, reflected a consistent increase in the proportion of violent trauma regardless of duration at two weeks 19 or 119 days 22 (of note: the third study, with duration of 41 days, found no change in violent trauma when assessment was limited to non-accidental pediatric trauma). 37 It was beyond the scope of this work to establish and assess, per city included in this study, a rating of "high" versus "low" pre-COVID violent trauma burden. However, such work is needed in the future in order to examine differential changes in violent trauma according to pre-pandemic conditions.
In any case, additional studies using rate data rather than proportional data are needed in order to provide a clearer, complete picture of the actual burden of intentional trauma during the pandemic. Such data would allow comparisons without obfuscation by any changes that may have occurred in non-intentional trauma during the pandemic.

Location
This review found that the majority of published studies examined hospital data based in urban populations. It is possible that that this reflects a bias in academic institutions being primarily based in urban centers, and/or an increased availability of ancillary funding to track these data with the support of a trauma registry staff within the hospital.
All studies demonstrating an increase in violent trauma were located in the United States. These findings reflect a noteworthy unique experience of the United States with regard to violent trauma during the COVID-19 pandemic. Across all of 2020, the United States had the highest number of COVID-19 related deaths overall in the world (approximately 330,000), but did not have the highest number of cases per 1 million people (US: 991; similar countries: Italy: 1,185, Spain 1,066, United Kingdom: 1,037, France: 953, Mexico: 945, Brazil: 896). 14 While interpersonal altercations increased world-wide during the COVID-19 pandemic, such cases may have disproportionately resulted in hospitalization in the United States due to increased acuity of injuries, secondary to relatively higher firearm accessibility. Pre-pandemic reasons for higher rates of violent death in the United States as compared to another, similar country were examined in the classic 1988 "Tale of Two Cities" study. In this analysis, Sloan and colleagues examined rates of violent assault and homicide between Seattle, USA and Vancouver, Canada. 57 They found that rates of these two events were similar in all categories of injury mechanism except for firearms: incidence of firearm-related assault and homicide were significantly higher in Seattle relative to Vancouver, a finding which the author attributed to differential access to guns. 57 The United States has nearly double the number of guns per 100 people as any other nation (US: 88; next highest: Switzerland, 45.7), 60 and a previous study limited to the United States showed an association between gun ownership and rate of violent death. 61 Duration Study durations ranged from 1 week to 181 days (approximately 6 months). While no definitive international trends emerged with regard to study length, continued monitoring of trends in violent trauma should still be undertaken, as the risk factors for violence remain present and will likely persist well-after the completion of national vaccination campaigns. Disaster medicine studies have demonstrated that mental health impacts of a disaster event can be noted at the population level nearly a year after resolution. 62 Within the context of violent trauma in particular, hospital registries have shown increased incidence and increased acuity for at least six months following a discrete event. 63 In contrast, the COVID-19 pandemic is on-going, with various national, regional, and local lockdowns going in and out of effect according to the status of infections in each locale.
Regional analyses limited to the United States, the only country where increases in violent trauma were recorded, demonstrated statistically significant increases in violent trauma during the first and second months of analyses (month 1: n ¼ 2 of 2 reporting; month 2: n ¼ 5 of 7 reporting), with no change during later months (examined as studies with duration of two and a half through six months). This finding may be related to the time period of data collection.

Limitations
This study included only studies that have been published in English. As such, there is a chance that our analyses are biased and limited to the experiences of Western countries (e.g., United States, United Kingdom, Australia, France, Italy, etc.). Indeed, this review did not find any studies from Eastern Asia and only one from South America. These gaps in the literature should be addressed in order to provide full understanding of the global experience of violent trauma and its associations with COVID-19. Nevertheless, this review did capture several studies from non-Western countries, from hospitals based in both urban and rural locations.
In addition, databases were searched approximately one year after the emergence and recognition of the Sars-Cov-2 virus in the human population. Global transmission lagged by a few months, and thus the time period for studies to have examined trends in violent trauma and have published on these data are likely the reason why average study duration of records included in this review was approximately two months. However, this review adequately captures the immediate societal reactions to the COVID-19 pandemic, lockdowns, social distancing, as measured by violent trauma incidence. Therefore, our data could provide a platform upon which policy-makers, particularly based in the United States where all increases in violent trauma were observed, can appropriate resources to address these immediate challenges.
In this study, violent trauma was defined very broadly. Studies reported on violent, interpersonal conflicts including domestic violence, child abuse, gunshot wounds, stabbings, and general assaults. Our definition of violent trauma was any study that reported on intentional, interpersonal conflict resulting in physical injury. This definition is broad, and thus may have contributed to the heterogeneity of our findings. For example, one may have expected gun-related violence to decrease while all-cause domestic violence increased during stay-at-home and lockdown mandates. Our review included hospital-based studies only, and theoretically could have included the exact diagnoses and injury mechanisms as described by the International Classification of Diseases. 64 Future researchers with the capacity to report out exact diagnoses should do so, in order to improve the surveillance and monitoring of violent trauma. Moreover, researchers examining changes in any disease over time should report on both the change in relative proportion of the outcome of interest, as well as the absolute rate of increase or decrease. Our review is limited in that each study performed either a proportion or rate analysis, instead of both concurrently. Presentation of both methods of analysis in the future will enhance scientists and clinicians understanding of the true nature of societal events upon trauma and other health conditions of interest.

Conclusions
The COVID-19 pandemic has shaped the world in a plethora of ways, including an indirect impact upon violent trauma. Studies remain conflicted regarding the exact nature of the impact; most studies that statistically assessed change in violent trauma reported no significant differences before and during the pandemic. Furthermore, the global impact of the pandemic upon violent trauma has not been felt consistently nor universally: the United States has uniquely experienced an increase in violent trauma presenting to hospitals. In particular, this impact of increased violence was skewed towards the initial onset of the pandemic, reported as increases in violent trauma as a proportion of all traumatic injuries. Longer-term studies are necessary in order to comprehensively dissect out regional and temporal trends, and to further quantify the absolute changes in trauma in order to mitigate an over-reliance upon proportion data.