Introduction

The population of the USA is aging. In 2010, people aged 65 years and older comprised 13% of the population; that proportion reached 15% in 2015 and is estimated to reach 22% by 2020 and 25% by 2060 [1]. An increasing life expectancy with increasingly healthy elderly patients contributes to a greater number of injured elderly seen at trauma centers and nontrauma centers alike.

This change in demographics has had a profound effect on injury epidemiology. We often think of epidemiology in terms of demographics, but the complete definition is that epidemiology is concerned with the incidence, distribution, and control of disease both in terms of prevention and mitigation. Thus, in order to better prevent and manage their population of patients, trauma care providers must concern themselves not only with understanding the overall rates of injury and admissions but also the likelihood that elderly patients will be admitted in greater absolute numbers as well as make up a greater proportion of trauma admissions.

Where Do the Data Come From?

In order to discuss epidemiologic phenomena, it is critical to understand the source of the epidemiologic data. This is a unique problem when discussing the injured elderly, as they are much more likely than younger patients to be treated at nontrauma centers. Recent data using the Nationwide Emergency Department Sample suggest that >50% of elderly patients with traumatic injury are not treated at trauma centers [2]. While that may have implications for care, it certainly has implications for understanding injury epidemiology, in that the majority of these patients are not described in the most common sources used by trauma practitioners and researchers.

One of the best sources of comparative epidemiologic data for hospitalized injured patients is the National Trauma Data Bank [3, 4]. This registry, operated by the American College of Surgeons, contains information from trauma centers throughout the USA. The number of centers contributing data has increased over time, from 405 in 2003 to 746 in 2014, and the annual number of submitted records has increased from 394,414 in 2003 to 860,964 in 2014. Although there has been some change in the NTDB inclusion criteria as well as their methods of analysis, there is still good information available about the change in injury epidemiology that has occurred over the last 10 years. TQIP, the trauma quality improvement project based on data from the NTDB, provides risk-adjusted information to participating trauma centers which is used to improve their performance over time. It does not provide publically available epidemiologic information.

Another excellent source of injury information is WISQARS, the Centers for Disease Control’s Web-based Injury Statistics Query and Reporting System [5•]. This website gives information about fatal and nonfatal injuries by mechanism, age, and region.

Change in Distribution and Mechanism of Injury

The NTDB data demonstrate the striking increase in the percentage of hospitalized elderly trauma patients >65 years of age, by decade (Table 1) [3, 4]. Data from WISQARS demonstrate the increase in the absolute number of both fatal and nonfatal injuries seen in the USA (Table 2) [5•].

Table 1 Percentage of elderly patients in the National Trauma Data Bank by decade, 2004 compared to 2014
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Table 2 Comparison of fatal and nonfatal injuries by age, 2004 vs 2014
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Motor Vehicle Collisions

The increase in the geriatric population results in an increase in the number of licensed older drivers; in 2012, there were almost 36 million licensed older drivers, a 34% increase from 1999. Per mile traveled, fatal crash rates begin to increase starting at age 70 and are highest among drivers age 85 and older. Elderly drivers are more likely to use seatbelts, drive during the day, and are less likely to drive while impaired [6]. As a result, despite their higher crash fatality rate, due to overall improvements in driver safety, there has been steady overall improvement in the death rates per 100,000 older drivers since the mid-1990s (Fig. 4) [7].

Falls

In the USA, one in five people over the age of 65 will sustain a fall annually. Of these, about one quarter will be injured and another quarter will restrict their daily activities for fear of another fall. Falls account for nearly 60% of injury-related ED visits and approximately 80% of injury-related hospitalizations for persons age 65 years and older. One of the big changes in epidemiology related to falls over the last decade has been the increasing awareness of the importance of ground level falls. Once excluded from registry data, it is now understood that 86% of falls are ground-level, and it is patient age rather than fall height that is the determinant of outcome. Falls have overtaken all other causes of injury death in the entire population >65; the death rate for those >85 is over three times that for people age 75–84. As the number of people in the oldest age groups increases, the imperative for fall prevention programs becomes even greater. Despite the widespread acknowledgement of the problem of geriatric trauma, well-established fall prevention programs exist in a minority of communities [8•].

Suicide

Suicide rates increase with age, peaking for men in the age group >85. For women who attempt suicide more often but are less successful than men, the peak age is 45–64. With the increasing population of elderly, the absolute number of successful and unsuccessful suicide attempts continues to increase. One of the issues in dealing with suicide prevention in the elderly is that risk factors present in younger patients who attempt suicide may not be present in the elderly, making standard screening tools much less effective [9]. Given the common interactions of elderly patients with the trauma system, this presents a unique opportunity to screen for this preventable disease.

Mortality

Injury continues to be an important cause of mortality for all ages, as the leading cause of death from age 1–44, and the 4th leading cause of death in all ages (Fig. 1) [10] (CDC ref). When considering death due to injury in those >65, the top three causes are falls, motor vehicle collisions, and suicide (Fig. 2). Compared to those younger than 65, the elderly have a higher case-fatality rate regardless of mechanism due to comorbid conditions, frailty, and undertriage [2].

Fig. 1
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Top ten leading causes of death by age 2014 (courtesy of CDC)

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Fig. 2
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Top ten leading causes of injury death by age, 2014 (courtesy of CDC)

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Falls have overtaken all other causes of injury death in the entire population >65; the death rate for those >85 is over three times that for people age 75–84. Death rates due to falls are regional, with several neighboring states having disparate adjusted mortality rates (Fig. 3). There are several potential reasons for this, including data capture and statewide fall prevention programs.

Fig. 3
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Mortality rate due to falls by state, 2008–2010 (courtesy of CDC)

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One of the difficulties with mortality statistics is the definition of death (Fig. 4). Although this would seem to be fairly straightforward, different data sources define dead on arrival to the hospital differently. There is variability in the use and availability of palliative care and hospice, along with different contributions of hospice discharge to overall mortality statistics. For an individual patient, this is quite unimportant, but from an epidemiologic standpoint, it is important to have standard definitions. Standardizing these definitions in order to better understand mortality in the injured elderly is one of the top recommendations from the American Association for the Surgery of Trauma’s Geriatric Trauma Committee [8•].

Fig. 4
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Motor vehicle crash deaths and deaths per 100,000 people 70 and older, 1975–2014

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Understanding of Prognosis and Discharge Disposition

Discussion about prognosis is an important part of care for trauma patients of any age, but arguably of even greater importance in the elderly. There are several challenges inherent in these discussions, with one of the greatest being the lack of accurate prognostic tools. The NSQIP surgical risk calculator, which provides information for geriatric patients undergoing elective surgical operations, is of limited to no use in trauma. Phelan et al. have come up with a new tool, the Geriatric Trauma Outcomes Score (GTOS), which can be used to predict in-hospital mortality for injured elderly patients with variables that are available in the first 24 h [11•]. It is the hope that the availability of tools such as this can help inform prognostic discussions and provide goal-concordant care.

Mortality is one important aspect of prognosis, but of equal and perhaps greater importance to the elderly is discharge disposition. The increased emphasis on decreasing length of stay for all diagnoses has led to an increased reliance on non-home discharges, particularly in the elderly population. Davidson et al. have shown in a trauma population in the Washington State that discharge to a skilled nursing facility (SNF) was associated with a 1.5-fold increase in mortality. Over a 14-year period ending in 2009, in-hospital mortality improved from 8 to 4.9%, while long-term cumulative mortality increased from 4.7 to 7.4%. Importantly, those discharged to an inpatient rehabilitation facility (IRF) did not have the same increased mortality as those discharged to a skilled nursing facility [12•].

The GTOS can also be used to predict discharge disposition, although it does so with less accuracy than predicting in-hospital mortality. Unfortunately, it appears that elderly trauma patients are becoming less likely to be discharged to an inpatient rehabilitation facility and more likely to be discharged to a skilled nursing facility. In a retrospective cohort study of trauma admissions from the National Trauma Data Bank National Sample Program from 2003 to 2009, the proportion of patients discharged to an SNF increased from 30.7 to 40.8% but decreased for those discharged to an IRF (25.9 to 15.6%) [13•]. Where our elderly patients go after discharge is critical to improving both mortality, quality of life, and prognostic information we give our elderly patients and their families. Better understanding of whether determinants of discharge are patient or system related will help us understand how to best interpret these data.

Frailty

Age is an easy thing to measure and to capture in data reports with minimal data collection burden. However, it is becoming increasingly evident that it is not just age that contributes to injury patterns and outcomes, but frailty. Frailty is a syndrome of decreased physiological reserve and resistance to stressors and as such is extremely difficult to capture without significant data collection burden. Joseph et al. have developed a trauma-specific frailty score that is predictive of outcome and relatively easy to use, provided that the information required has already been captured. However, much of the information required (help with toileting, help managing money, health attitude) is not captured routinely and so the tool cannot be used unless the questions are asked routinely on admission [14]. The tools used by Maxwell investigating frailty similarly require in-person questionnaires to be used [15].

Due to the difficulties in data collection, it is not likely that frailty will ever replace age in epidemiologic studies. That does not mean it is not important—epidemiologic information is information about populations of patients, and age can serve to provide information that is helpful for looking at trends over time, comparing broad age categories, and informing injury prevention programs. Frailty is much more likely to be helpful in determining an individual patient’s prognosis and for investigating potential interventions that may be effective in altering the course of disease.

Conclusion

Trauma surgeons clearly recognize the increasing problem of geriatric trauma [8•]. A better understanding of the impact of the problem and the specific epidemiologic patterns that exist at local, regional, and national levels should help drive trauma care practitioners to address the problem and improve outcome. Some of the suggestions include addressing geriatric triage criteria, using of geriatric-specific protocols and workforce, and working collaboratively to improve care post-discharge [8•]. Other suggestions include establishing centers of excellence for geriatric trauma care. Although the sheer volume of geriatric trauma makes this impractical as the sole solution, a recent analysis demonstrates that outcomes in the geriatric population are improved in centers that treat a higher number of elderly trauma patients. Interestingly, the majority of the centers in this NTDB-based analysis were level 2 centers, suggesting there may be best practices that can be learned from these higher-performing centers [16•].