Sex differences in work-related traumatic brain injury due to assault

Abstract

OBJECTIVES: To examine the etiology, prevalence and severity of assault-precipitated work-related traumatic brain injury (wrTBI) in Ontario, Canada through a sex lens.

METHODS: Cross-sectional study using data abstracted from the Ontario Workplace Safety and Insurance Board (WSIB) claims files in 2004. Descriptive analyses were conducted to determine the distribution of worker/employment/incident characteristics.

RESULTS: Workplace physical violence that resulted in a TBI accounted for 6.6% percent of all TBI injury claims. Female workers, primarily in the health care/social services sector, accounted for over half of all TBIs. Most workers were assaulted by consumers/clients. Forty five percent of injuries occurred among workers with less than 3 years of employment.

CONCLUSIONS: This paper identifies profiles of workers and workplaces for targeted preventive efforts. Future studies are needed to further address risk factors by sex and outcomes, such as length of disability and health care cost.

Keywords

Traumatic brain injury workplace assault occupation epidemiology

Abbreviations

TBI

Traumatic brain injury

WrTBI

work-related traumatic brain injury

WSIB

Worker’s Safety and Insurance Board

1 Background

Traumatic brain injury (TBI) is a major public health problem worldwide, causing death or disability [1 –3]. Even a mild injury can have long-term consequences [4]. An estimated 628,000 Canadians, 2% of the country’s population, currently lives with disabilities caused by brain injury [5]. Early onset of TBI poses enormous cost to survivors, their families, and society in the form of loss of productive life, competitive employment, and other meaningful roles. Most causes of TBI such as falls, motor vehicle crashes, and assaults are preventable, and increased public awareness, dedication to preventive measures, and research on the circumstances of injury are needed to control the human and economic costs of injury [6 –8].

TBI occurring at work, work-related TBI (wrTBI), has not been studied in detail, possibly due to its low incidence relative to other injuries occurring in the workplace [9 –11]. However, evidence has emerged in recent years describing TBI as a chronic condition [12], with sequelae affecting multiple aspects of living, years after the injury [13]. Efforts directed towards awareness and prevention can make a substantial difference to occupational health and safety. Colantonio & Comper [14] examined demographic and clinical characteristics, post-injury symptoms and occupational factors related to wrTBIs in Ontario. Most injuries occurred in males over 45 years of age, and the industry sectors claiming most wrTBIs were those of manufacturing (22.3%) and construction (19.1%).

An understudied cause of wrTBI is violence in the form of physical assault. In Ontario, the Occupational Health and Safety Act seeks “to secure workers and self-employed persons from risks to their safety, health and physical well-beings, arising out-of, or in connection with, activities in their workplaces” [15]. Workplace violence was incorporated into the act in 1990, when violent acts became an increasingly recognized threat to workers in all industries and occupations, causing critical injuries and death [15]. Recent legislative changes suggest that assault at work remains a broad public health concern. The economic costs of wrTBI due to assault have not been studied thus far; however, costs of workplace assault in general are striking, with estimated charges of $4.2 billion in the US annually [16]. Hidden in these numbers are the more profound costs and effects on the physical, personal, emotional, and professional well-being of the victimized and injured, including demoralization related to job performance and satisfaction [17], also indicators of organizational and societal health [18]. In a systematic review of workplace violence research published between 2000 and 2012, the authors highlighted the issue as common, costly, and occurring throughout occupational sectors [19].

According to Kim et al. [20] of all wrTBIs occurring in 1993–2001 in Ontario, 3.6% were due to physical assault. Because the sample was restricted to seriously injured workers treated at chief trauma hospitals, it is likely that the overall number of wrTBIs from physical assaults is underestimated, as not all persons injured will seek medical care (e.g. mild TBI and older patients) [21]. According to the British Columbia Public Service, reasons for unreported workplace violence incidents include employees’ lack of awareness on the issue, fear of being blamed, and reluctance to make the effort to report given the belief that no action will be taken in response [22].

1.1 Purpose

Surveillance for monitoring and describing wrTBI due to assault is lacking and timely given the impact of the TBI itself as well as the circumstances surrounding such an event. To address this gap, this study aimed to (1) assess the extent of work-related assault resulting in TBI based on sex and across various occupational sectors in Ontario; (2) examine the worker demographic and workplace characteristics related to wrTBI due to assault; and (3) provide a better understanding of the circumstances surrounding these violent incidents.

2 Methods

2.1 Study design and data collection

This project involved secondary analysis of wrTBI data drawn from Worker’s Safety and Insurance Board (WSIB) claims in Ontario, Canada in 2004. For details regarding the original study protocol, see reference 10. The study was approved by the Toronto Rehab-University Health Network research ethics board. The data was based on a case series design, aimed to examine all WSIB claims with a 2004 injury date and a physician-confirmed diagnosis of ‘concussion’, ‘closed head injury’, ‘contusion’, or ‘head injury with sequalae consistent with brain injury’ [10]. In total, 1,006 files met eligibility criteria for positively identifying TBIs. Of the 1,006 files, 66 claims (6.6%) cited physical assault as the cause of TBI.

Full descriptions of the physical assault events were transcribed, allowing more qualitative/thematic analysis and adding descriptive context to the incidents. Minitab software was used for statistical analysis. A small portion (<3%) of the item-specific information was missing, and was converted to missing values before analysis.

2.2 Variables studied

Socio-demographic data collected included sex (male or female), age (ordinal variable with 5-year age intervals), type of occupation/occupational sector and years employed. Injury related data collected included mechanism of injury and contributing factors (e.g. shift, time/date of the injury, and weekday), lost work time in days. Narrative details were abstracted from the claims records to record workers’ social context (e.g. injury circumstances, duties performed at the time of injury) and violence characteristics (e.g. relationship to perpetrator, use of force) at the time of injury.

Using a descriptive content analysis approach, each worker’s summary was reviewed; then using coding strategies, one investigator identified types and sources of assault, forming a coding construct. Two researchers then used the coding template to independently categorize episodes of wrTBI. Inter-rater reliability for coders was high (96%).

2.3 Data analysis

Frequency distributions and measures of central dispersion were generated for demographic and injury variables. Statistics Canada was utilized for data on employment by sex in Ontario for the 2004 year, to be used as denominator data in calculation of sex-specific rates [23].

Qualitative data was categorized independently by two researchers into four types of violence in the workplace: Type 1 (external/intrusive violence), for crimes committed by assailants with no relationship to the workplace; Type 2 (consumer-/client-related offence), for interactions with customers/patients/students, etc.; Type 3 (relationship violence), where injury was caused by a co-worker or partner, and Type 4 (organizational violence), for premeditated attacks carried out by a coordinated force, usually a group of people [24].

3 Results

In 2004, the total number of lost time claims due to any injury was 74,332 [9], of which 1,006 (1.35%) were claims with a confirmed diagnosis of wrTBI. Sixty six claims (6.6%) cited physical assault as the cause of TBI. The majority of wrTBIs due to assault were classified as mild traumatic brain injury (mTBI) or concussion (50 or 76%), followed by head injury/contusion or head injury/lacerations/contusions (5 or 8% each) diagnoses. The remaining six participants (9%) did not have their injury severity established.

3.1 Demographic characteristics

In 2004, there were a total of 66 workers’ compensation claims (6.6% of total) in Ontario with TBI caused by assault. Age ranged between 20 and 64 years, with a sample median of 37 years. Assault-related wrTBI claims occurred at a greater frequency in female employees, who comprised 39 (59.1%) of the claimants. Health care/social services aides constituted the largest claimant sector (27 claims), followed by police/guards/security/law enforcement/public administration personnel (22 claims). To designate the former, we will use the umbrella term ‘law enforcement/public administration sector’. Other occupations included those in the education (ten claims), and transportation (five claims) sectors.

Statistics Canada was utilized to obtain data on employment by sex in Ontario for the 2004 year [23]. The resultant estimated assault-related wrTBI claim rate was 9.85 per 1 million Ontario employees in 2004, 11.79 per 1 million female workers and 8.4 per 1 million male workers. Sex differences were also noted within occupational groups. The highest rate of TBI due to assault in 2004 occurred in the health care/social services industry, at a rate six-fold higher for females than males. A four-fold higher rate was observed for female workers in the educational sector. Within the law enforcement/public administration sector, male injuries comprised the majority at a rate 13 times higher than that for female workers. With respect to occupational tenure, the highest proportion of victims were those employed fewer than 3 years (30 cases or 66%) (Fig. 1).

3.2 Temporal characteristics

Potential differences in TBI as a result of assault by time of day, day of week, and season were examined. For both men and women, most injuries occurred either late in the morning or early in the afternoon. Peak months and days were November and March and Mondays and Fridays, respectively (Fig. 1).

3.3 Distribution by assault type

The primary perpetrators of the events leading to wrTBI were examined (Fig. 2). The most common cause of wrTBI was Type 2 assault (consumer/client-related violence) (47 cases or 71%). Violent acts resulting in TBI were committed by clients (i.e. recipients of paid services) (18 cases or 27%), customers (i.e. recipients of intangible commodities such as health, administrative/law services, etc.) (15 cases or 23%), suspicious individuals (i.e. for the police/security sector) (ten cases or 15%), students with and without special needs (nine cases or 14%), inmates (i.e. convicts) (five cases or 8%), unidentified assailants (i.e. strangers) (five cases or 8%) and co-workers (three cases or 5%). Injuries to the head and face were listed as the cause of TBI in the majority of claims by both men and women (24 and 28 cases or 36% and 42%, respectively). Women, however, sustained additional injuries to other body parts (e.g. neck, arms, etc.) more often than men (79% vs. 21%).

3.4 Cost of claims

The total number of days of disability for the studied period was 8,953. Women accrued more days of disability than men (5,166 vs. 3,787). Fifteen of the 66 workers, ten females and five males, returned to work before the end of data collection (December 31, 2004). Of those who did not return to work, 38 claimants (17 male workers, 21 female workers) were off work for more than 60 days.

3.5 Qualitative data

Over 40% of assaults resulting in wrTBI (27 cases) occurred when dealing one-on-one with clients/patients, of which one third occurred when workers dealt with irate or angry persons. Twenty three percent (15 cases) of all cases occurred in attempts to restrain an inmate or in following of suspicious individuals. Twelve percent (eight cases) of injuries were sustained when workers dealt with disabled/special needs individuals or those with awareness issues. Seven percent of assaults occurred in a mobile workplace (i.e. transportation sector).

To protect confidentiality and limit identifiable information, no further detail is provided on the circumstances of assault incidents.

4 Discussion

To our knowledge, this is the first paper examining in detail wrTBI due to assault. The study was based on a representative WSIB population. As noted, the numerator for calculation of rates was the number of workers who submitted a claim in 2004 with a TBI diagnosis, and the denominator was the number of male and female workers employed in 2004 in Ontario, by occupational sector, provided by Statistics Canada. We believe these to be conservative estimates given that only about 70% of employees in Ontario are insured by WSIB [25].

4.1 Types and prevalence of wrTBI due to assault

We reported a prevalence of assault-related wrTBI in Ontario over the 2004 year of 6.6% – much higher than previously reported by Kim et al. [20] (3.6%) and slightly higher than that reported for Ontario overall (5.6%) [26].

The differences may be due to variability in yearly distributions, environmental settings, as well as the fact that the Kim et al. study was based on the Ontario Trauma Registry, which included only serious injuries from lead trauma hospitals [20]. In the US, nonfatal, wrTBI cases due to assault were reported to range from two to six percent of all wrTBIs [27, 28].

Female workers in our study were at a greater risk for assault resulting in TBI (59.1% women vs. 40.9% men), disproportionate to the 42.3% of female TBI cases found in the sample overall, regardless of mechanism of injury [10]. Nevertheless the values show both sexes are at risk for occupational acts of violence causing serious injury.

We found risk of injury to vary by occupation. At highest risk were workers employed in the health care/social services sector (i.e. nurses, personal support workers). Health care/social services aides comprise less than 10% of the working population in Ontario, however, they account for over 40% of the assault-related wrTBI claims filed. The next high-risk sectors included the law enforcement/public administration sector, where officers’ duties involve interactions with individuals who may behave in a threatening manner. Since claims tend to focus on the victim and the duty performed at the time, with less emphasis on environmental factors, we were unable to explore perpetrator characteristics, highlighting the importance of inclusion of detailed information about the work setting at time of incident in future studies of wrTBI. Other riskiest sector was educational services.

Our findings are consistent with high-risk occupational sectors reported in previous studies on workplace violence [29, 30]. Hartley et al. found that the health services sector accounted for the highest number of US workplace assault victims (53%), followed by protective services (16%) and education (13%) [30].

The majority of our cases were Type 2, involving clients or patients. A study by Bowman and Rich, classifying incidents by assault type, found that more than one-quarter of all workplace violence incidents involved an assailant with a personal relationship with the victim [31]. These numbers are higher than in our study, where such relationships accounted for 13% of incidents.

4.2 Injuries sustained

Analysis of the injury types found that head and face injuries accounted for most claims by both sexes. These findings were not unexpected [32]. However, female workers in our sample more frequently sustained additional injuries to other body parts (e.g. neck, arms, etc.). The tendency of the female worker to be unable to escape further attack by a perpetrator may be the result of unequal power distribution and the use of hands and arms for self-defense [33]. A recent study from a nursing home in Spain found that more than 60% of the health professionals were assaulted by patients they cared for in the previous year, with male residents being the perpetrators in most cases [34].

4.3 Risk by occupational sector

Assault-related wrTBI incidents observed in the health care/social services occupational sector were primarily inflicted by clients/patients. This is consistent with previous reports on violence in the workplace [35, 36]. One study reported that assault rates in the health care sector were higher in places where the staff-patient ratio was lower, an indication that patients housed there may have more serious diagnoses [37]. A high risk of workplace assault was also reported within such sectors as mental health, geriatric and rehabilitation care [38]. A recent study showed that perceived health risk varied between categories of employees within the health care sector. Nursing staff were exceptionally stressed by both qualitative and quantitative job overload, including shiftwork, physically demanding postural change, bathing assistance, lack of supervisor and co-worker support, while physicians perceived health risk to be rooted in long working hours. Further, administrative workers perceived lighter stress than all other employees in health care services [39]. While we did not collect data on staff-patient ratios and sub-groups within health care/social services aides, this should be considered in future studies.

4.4 Other relevant factors

This study found that workers under 30 years of age were at a higher risk of sustaining wrTBI due to assault, consistent with previous research on workplace violence in general. McCall & Horwitz studied workplace violence against nurses, reporting the 41–50 year age group to experience a lower incidence of verbal assault than nurses less than 30 years of age [40]. Another study on risk factors for non-fatal violence at the workplace distinguished young age and male sex as factors increasing risk [41]. This deviated from our results, where female workers were at higher risk for sustaining assault-related wrTBI in general and within the health care/social aides, and educational occupational sectors. We did however find the frequency of injured males within the law enforcement/public administration sector to be thirteen-fold higher compared to females in the sector. A study among Finnish security guards showed an association between workplace violence and male sex, young age, and lack of work experience [42]. More recently, a study from the educational sector reported that history of any violent victimization was found to be strongly associated with risk of experiencing work-related physical assault, even after controlling for potential confounders and adjustment for non-response [43]. The issue of subsequent victimization has not been explored in this study, however this caveat is consistent with previous reports from the health care sector [44], suggesting that having experienced abuse in the past creates vulnerability to future risk. This concern requires further exploration with regards to wrTBI.

We found that job tenure influenced the risk of sustaining wrTBI due to assault. Our findings suggest that longer work experience reduces the risk. More experienced employees may anticipate or recognize a potentially violent situation earlier, and be more experienced in diffusing potential or escalating aggression. Young age at work has been associated with greater injury risk [8, 46]. It is possible younger workers more often report injury, indicating a possible cohort effect. Female employees are reportedly more likely to report injury than male colleagues, particularly for violent interactions such as in the law enforcement sector [42].

4.5 Monthly/weekly/hourly distributionof assault-related wrTBI

We found the most injuries occurred in November and March, consistent with reports on monthly distribution of sexual assault incidents among women [47]. Other studies described workplace violence and sexual harassment, although theoretically distinct constructs, as co-occurring in the context of home-based and health care services [48, 49].

The time of the day was an alarm in this study. For both sexes, most violent acts resulting in wrTBI occurred in late morning and early afternoon, unexpected, given earlier studies reporting highest rates in the evening and early morning hours [29, 40]. The observed pattern can be explained in part by the fact that most of our sample worked the day shift, and the specifics of their relationship to the perpetrator (mostly clients).

In this study, assault-related wrTBIs peaked on Mondays and Fridays for both sexes. Curiously, a national survey on work-related violence reported that acts of vandalism were more prevalent on Mondays and Fridays as well [50]. Downing et al. (2003) observed a peak in hospital admissions for physical assault on Friday nights [51]. This pattern may reflect a decline in workers’ ability to react effectively to a threat, possibly due to aggregation of tiredness/fatigue at the end of the work week [52]. Then again, greater distraction at the beginning of the week may render the worker more vulnerable to attack. Another possible explanation is the accumulation of a client’s agitation due to lack of support/care over the weekend.

4.6 Sex differences in victimization patterns

As noted, female workers were found to be at greater risk for sustaining TBI due to assault at the workplace than male workers (11.8 vs. 8.4 per 1 million employees). Sex appeared implicated in patterns of victimization at the workplace causing TBI by various mechanisms. First, a high total rate of TBI in female workers – women represented a disproportionally higher proportion of the victims in the health care/social services and educational occupational sectors, while male workers showed the same pattern in the law enforcement/public administration sector. Sex also appears to influence the nature of injuries sustained. In addition to injuries to the head and neck, women sustained more injuries to other body parts compared to men. Finally, we observed differences in disability outcomes between sexes. While our data provides limited information to thoroughly discuss this issue, the longer length of disability for women compared to men (5,166 vs. 3,787 days) may suggest greater impact of the injury on women. Previous research reported greater likelihood of female workers leaving a job because of violence at work [53].

Further investigation is required to determine if sex differences exist in with respect to workplace assault (e.g. psychological distress, perceived social support, etc.) and prolonged recovery from wrTBI and occupational disability.

4.7 Significance of wrTBI due to assault

Although less common relative to other occupational injuries, TBI at the workplace is a significant event that affects a worker at the cognitive, behavior, and emotional levels [54]. While most injuries in our sample were classified as mild TBI or concussion, the resulting length of disability was considerable. The assault mechanism of TBI in the occupational setting requires further investigation for its implications to be established more concretely; nevertheless, our research on the poor outcomes of mild TBI due physical assault is present and sheds light on the consequences and significance of these events. While mild TBI due to any mechanism of injury has been associated with the new onset of discrete psychiatric disorders, including depression, mania, psychotic, and anxiety disorders [55], when assault and TBI coexist, the combination is expected to accentuate the degree of distress, impede physical and psychological recovery, and necessitate greater healthcare resources [56].

4.8 Strengths and limitations

The WSIB covers approximately 70% of the workers in Ontario, and thus, the prevalence/rates of wrTBI due to assault reported here are likely underestimates, as there is no guaranteeing the remaining 30% have similar characteristics. As such, caution should be exercised in generalizing findings across the entire Ontario workforce. That said, the 70% encompasses the high-risk categories (i.e. health, law enforcement, education) within the WSIB framework. Another limitation is our period of study of one year. A longer period of time is necessary to examine the full scope of the mechanisms of injury at the workplace. We also recognize that not all wrTBIs may have been captured with the codes used. For example, some persons with TBI may have been listed under code “multiple injuries”, not explicitly identifying TBI. Furthermore, while we assessed the cost of claims based on data on time off work, other potentially significant medical and healthcare costs were excluded. Finally, the psychological trauma that accompanies assault at the workplace is a difficult but significant factor to study, particularly when a brain injury is also present. Future studies should review such data, as workplace violence can be both demoralizing and debilitating [57].

Notwithstanding, this is, to our knowledge, the first study in the Canadian context to examine factors related to assault-related wrTBI in a representative sample of workers. It is also the first to review TBI by work-related assault through a sex lens. The text analysis of TBI injury claims from the Ontario WSIB represents new possibilities for exploratory insights into the particulars and details recorded in the WSIB compensation system [58]. Our comprehensive analyses of the typology and exposure situations progress into distinct and meaningful clusters of factors that can increase the likelihood of wrTBI due to assault, which can be used in development of detailed suggestions for safety management and injuryprevention.

5 Conclusions

Factors found to be associated with increased or decreased risk for wrTBI due to assault (e.g. sex, occupational sector, experience) provide opportunity for further investigation of the even circumstances through surveillance work with the goal of development of appropriate interventions to reduce and control such injury.

Conflict of interest

None to declare.

Funding

The first author was supported by the 2012/2013 Toronto Rehabilitation Institute Scholarship, the Ontario Graduate Scholarship 2012/2013 and the 2013/2015 Frederick Banting and Charles Best Doctoral Research Award from the Canadian Institutes of Health Research. Support was also provided through the Ontario Work Study Program, the Ontario Neurotrauma Foundation, and the CIHR Canadian Traumatic Brain Injury and Violence Research Team. Dr. Colantonio was supported by the Saunderson Family Chair in Acquired Brain Injury Research and the Canadian Institutes for Health Research Grant-Institute for Gender and Health (#CGW-126580).

Authors’ contributions

TM, AC, JL – study concept and design; AC – acquisition of data; TM, SM – statistical and qualitative analysis; TM – drafting of manuscript; All authors – critical revision of manuscript, review of content.

Footnotes

Acknowledgments

We wish to express our gratitude to the Ontario Workplace Safety and Insurance Board for their collaboration in this study.

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