Traumatic brain injury (TBI) is a major public health concern in the USA. Annually, 52000 people die because of a TBI, while 275000 are hospitalised, and an additional 1.4 million people are treated and released from emergency departments (ED).¹ In 2005, an estimated 3.3 million people were living with a TBI-related disability in the USA.² TBI can cause temporary changes or permanent disabilities that may impact physical, cognitive and/or emotional skills.¹³ Although national estimates for non-fatal work-related TBIs (WRTBI) are not available, a recent study of a Washington state trauma registry and workers’ compensation claims found that TBIs accounted for 20% of all work-related injuries from 1998 to 2008.⁴ In another state-based analysis in Minnesota, about 5% of all TBIs from 1999 to 2008 were WRTBIs.⁵ TBIs impact the lives and functioning of the injured workers, and they can also result in substantial claim costs to the employer and insurer.²⁶⁷ Furthermore, return to work after a TBI can be difficult due to physical, cognitive and emotional symptoms.²

In the USA, studies on non-fatal TBIs have focused on the general population, professional football players and military personnel, but only a few studies have focused on TBIs that occur at work. Existing research on non-fatal WRTBIs in the USA is largely limited to single states, genders, specific age groups or particular industries.^4–689 The dearth of research in this area may be attributed to methodological issues, such as difficulties in ascertaining TBI cases and identifying WRTBIs from hospital records.^1210–12 Work-related fatal TBIs were reported at the national level, but nonfatal TBIs were never described.¹² Given the potentially devastating impact of TBI on workers, research is needed to better understand the epidemiological characteristics of non-fatal WRTBIs at a national level to help inform prevention strategies. Thus, the objectives of this study were to (1) examine non-fatal WRTBIs treated in US EDs, (2) describe the leading events associated with WRTBI and (3) assess injury trends from 1998 through 2007. This report presents the first detailed analysis of non-fatal WRTBIs in the USA.

From 1998 through 2007, 586 600 (CI=±150 000) weighted number of non-fatal WRTBIs were treated in EDs at a rate of 4.3 (CI=±1.1) per 10 000 FTE (table 1).

The overall rate of non-fatal WRTBIs increased by an average of 0.21 per 10 000 FTE per year from 1998 through 2007 (p<0.0001). The rate of WRTBIs treated and released increased annually by 0.16 per 10 000 FTE (p<0.0001). Also, the rate of WRTBIs resulting in hospitalisation increased by an average of 0.04 per 10 000 FTE per year (p<0.0001). While 90% of workers with WRTBIs were treated and released, 10% were hospitalised. By comparison, only 2% of all ED-treated injuries in NEISS-Work (ie, all non-fatal work-related injuries) were admitted for hospitalisation. Of all WRTBIs in this study, the majority (68%) of WRTBIs were internal organ injuries to the head (n=401 300; CI=±131 900), 30% were concussions (n=175 100; CI=±47 100) and 2% were fractures to the head (n=10 200; CI=±3800; data not shown).

Men had a significantly higher non-fatal WRTBI rate compared with women (table 2). The youngest workers (15–24 years) experienced the highest TBI rates among all workers, followed by the 25 year to 34-year age group. The youngest workers had a significantly higher risk for WRTBI than the oldest workers (55 years and older).

Non-fatal WRTBIs were most commonly associated with contact with objects and equipment and falls (table 3; data not shown by minor event categories). Contact with objects and equipment was the leading WRTBI event for workers aged 15–44 years and the majority was due to being struck by building materials (35 000; CI=±8700). Falls were the leading event for workers aged 45 years and older. For workers 55 years and older, falls accounted for more than half of WRTBIs and the majority resulted from falls on the same level (22 100; CI= ±5800). The youngest workers had the highest TBI rate among all workers from contact with objects and equipment. The youngest workers also had the highest fall-related TBI rate among all workers, followed by workers 55 years and older. From 1998 through 2007, the fall-related TBI rate per 10 000 FTE among young workers increased 54% from 2.0 (CI=±0.9) in 1998 to 3.1 (CI=±1.6) in 2007. During the same period, the fall-related TBI rate per 10 000 FTE among oldest workers increased 136% from 1.3 (CI=±0.7) in 1998 to 3.1 (CI=±1.5) in 2007 (data not shown).

Corresponding to the annual increase in overall WRTBIs, certain event-specific WRTBI rates also increased significantly. From 1998 through 2007, there was a significant average annual increase in WRTBI rates per 10 000 FTE from falls (0.10, p<0.0001), assaults and violent acts (0.04, p<0.0001) and transportation events (0.03, p=0.0002) (figure 1). The average annual WRTBI rate per 10 000 FTE related to contact with objects and equipment also increased, but this increase did not reach statistical significance (0.04, p=0.07).

In the single-year industry analysis from 2007 NEISS-Work data, the highest WRTBI rates were in agriculture, forestry, fishing and hunting; transportation and warehousing; and arts, entertainment and recreation (table 4). However, the greatest number of WRTBIs occurred in the construction industry. In the transportation and warehousing industry, the majority of WRTBIs were associated with contact with objects and equipment (2220; CI=±1100; 35%), followed by transportation-related events (1700; CI=±700; 28%) and falls (1700; CI= ±1000; 28%). In the construction industry, falls accounted for more than half the WRTBIs (5100; CI=±2000; 54%) and contact with objects and equipment accounted for 40% (3700; CI=±1700). Since industry codes were only available for 2007, some industries could not be partitioned any further due to data not meeting reporting requirements.

The findings presented in this study demonstrate a significant increase in the overall rate of non-fatal WRTBIs from 1998 through 2007, as well as in the rates of treated and released WRTBIs and hospitalised WRTBIs. The increase in non-fatal WRTBI rates during this period could be indicative of an increased public awareness of the importance for early diagnosis and medical care for TBI.¹ Also, the increase in hospitalisation rates likely demonstrates a true increase in WRTBIs. These increases can lead to an increase in lost wages and medical costs, especially from hospitalisation. The cost of hospitalisation due to TBIs may account for 90% of the total TBI medical costs.¹⁷ Additionally, short-term and long-term consequences of TBI can pose difficult, if not insurmountable, challenges to resuming work and other daily activities. Thus, it is important to prevent WRTBIs and reduce occupational injury costs and preserve the existing workforce.

Similar to previous studies, men were at an increased risk for non-fatal WRTBI compared with women.⁵¹⁸ While data in this study could not be stratified by gender and occupation, this increase may be due to more men working in occupations that may be at greater risk of WRTBIs due to dangerous and physically demanding work.¹⁹

Consistent with previous studies, our study found that the youngest workers had an increased risk for non-fatal WRTBI compared with other age groups.⁸¹⁸ Factors associated with this increased risk include an inability to assess risks associated with hazards in workplaces.²⁰ A general lack of job experience and safety training may also increase injury risks.²⁰ Although no prevention strategies are specifically aimed at reducing WRTBIs among young workers,¹² strategies targeted at preventing injuries to young workers might also reduce TBIs. For example, NIOSH developed a curriculum to help students understand the importance of basic knowledge of occupational safety and health before they enter the workforce.²⁰ This curriculum helps students identify hazards, prepares young workers for emergencies, provides knowledge of safety measures for reducing injury risk, and assists young workers in understanding their legal rights.

From 1998 through 2007, fall-related WRTBI rates significantly increased, and the youngest and oldest workers were found to be most vulnerable. Prior research also found that the youngest⁹ and oldest workers were at an increased risk for fall-related WRTBIs in the workplace.⁵¹²²¹ We found that among the oldest workers, fall-related TBI rates have more than doubled over the 10-year period. The increase in fall-related WRTBIs reflected the increase in overall fall-related TBIs among the oldest populations.¹²² Thomas et al²³ reported that as age increases, so does the rate of hospitalisations and fatalities due to fall-related TBIs. Prevention of fall-related WRTBIs is extremely important in the workplace, especially for older persons who may have slower and more costly recoveries.²⁴ Pre-existing health conditions, physical deficiencies, impaired mobility and gait, medication use and sensory deficits have been associated with increased risk for fall-related TBI among older persons.²⁵²⁶ Prevention of these injuries is important, as the number of older workers in the US workforce is increasing.²² Fall-related events may be prevented through behavioural measures, such as regular exercise, regular vision checkups and education;²⁷ elimination of fall hazards, such as poor lighting, slippery floors, uneven surfaces; and by following workplace protection standards including installing guardrails and personal fall arrest systems.²⁸²⁹

TBIs can be serious injuries that may require prolonged medical care. In our study, we found that the proportion of ED-treated WRTBIs requiring hospitalisation was higher than the proportion of all ED-treated occupational injuries requiring hospitalisation. To avert long-term consequences, TBIs require prompt attention and early diagnosis.¹⁴ While TBI awareness among professional athletes and military personnel has improved,³⁰ promotion of TBI awareness among the general workforce is limited. Thus, a strong educational message aimed at workers is needed to promote awareness of causes, signs and symptoms, and consequences of WRTBIs, as well as the importance of early diagnosis and medical care. Raising awareness of the benefits of WRTBI medical care may increase the number of workers with head injuries seeking medical care and reduce long-term negative effects of TBIs. The Centers for Disease Control and Prevention has developed a series of Heads-Up toolkits to educate parents, athletes, coaches, physicians and school employees, about the importance of identifying and preventing a TBI.¹⁴ A similar resource focusing on TBIs in the workplace could be developed to educate employers and workers about the identification, treatment and prevention of WRTBIs.

Although not all WRTBI patients seek treatment in EDs, NEISS-Work is a good source for capturing WRTBIs because anyone sustaining a head injury is often encouraged to seek immediate medical attention in EDs.¹⁵³¹ However, using NEISS-Work data has a number of limitations. First, the small number of hospitals in the NEISS-Work sample contributes to large SEs. Second, International Classification of Diseases, 9th Revision, Clinical Modification (ICD-9-CM) codes are not available in NEISS-Work and it has no TBI case identification methodology. To overcome this, we used a TBI case definition based on previous NEISS research on TBI case ascertainment.¹⁰¹¹ Thompson et al¹¹ evaluated the sensitivity of this case ascertainment and confirmed that a large number of true TBI cases can be identified using their definition (91% sensitivity). Also, they found that the NEISS TBI classification codes corresponded well with the ICD-9-CM codes.¹⁰¹¹ Third, following their prescribed case identification methods, 2% of WRTBIs were skull fractures. Brain injury involvement cannot be confirmed for these cases as that information is not available in NEISS-Work. Fourth, NEISS-Work only collects data from EDs and excludes patients who receive medical treatment in other settings (eg, physician offices and outpatient settings). Also, potential TBI cases due to contusions, abrasions, haematomas, or lacerations to the head were missed with this case definition. Therefore, the data presented in this study are likely an underestimate of the overall burden of WRTBIs in the USA. Fifth, NEISS-Work does not collect TBI severity measurements, which are important in assessing the burden of TBI by severity type for developing prevention efforts. Sixth, industry data were only available for 2007, limiting an industry-specific in-depth analysis.

Non-fatal WRTBIs are one of the most serious workplace injuries among ED-treated work-related injuries as evidenced by the higher proportion of WRTBIs that resulted in hospitalisation compared with overall ED-treated occupational injuries. The number and rate of WRTBIs steadily increased from 1998 through 2007. The magnitude of TBIs and upward trend in TBI rates observed during the 10-year period highlights the need for effective workplace prevention methods. Specific areas of concern include youngest workers, who have the highest risk for WRTBIs of all age groups, especially from contact with objects and equipment and falls, and oldest workers, who most commonly sustain a WRTBI via a fall and may have difficulty recovering from such an injury.²⁴ For future research, detailed analyses of WRTBIs across industries and occupations, including efforts to characterise the severity of the injury with a focus on age, are needed so that effective and targeted prevention strategies can be developed and implemented to reduce these injuries. Such data can inform prevention efforts and could have a substantial impact on reducing WRTBIs as well as assisting in identifying issues related to recovery and return to work after TBI.