Medical Comorbidities and Trauma




© Springer International Publishing Switzerland 2016
Lawrence M. Gillman, Sandy Widder, Michael Blaivas MD and Dimitrios Karakitsos (eds.)Trauma Team Dynamics10.1007/978-3-319-16586-8_20


20. Medical Comorbidities and Trauma



Harvey G. Hawes  and John B. Holcomb 


(1)
Center for Translational Injury Research, 6410 Fannin Street UPB 1100, Houston, TX 77030, USA

 



 

Harvey G. Hawes (Corresponding author)



 

John B. Holcomb



Keywords
ComorbidityInjuryAgingElderlyPreexisting medical conditionPhysiologyInjuryFrailty



Introduction


The sum of injury deaths worldwide in 2010 was greater than malaria, tuberculosis, and HIV combined, and has increased by at least 24 % over the last decade [1]. This staggering trauma pandemic has been thought to predominately impact the young healthy portion of the population. However, when intentional and unintentional injury data are combined, the greatest years of life lost in the USA is due to trauma up to the age of 75, ahead of even cardiovascular and malignant diseases [2]. Deaths from injury only represent a small fraction of the total burden of injury; roughly tenfold more people survive their injury, and many of them attempt to seek medical attention. Increasingly, the demographics of injured patients are changing. The world is aging and as they age they collect a list of medical comorbidities. It is this rapidly growing segment of the population that this chapter is written about.

The term “elderly boom” describes the demographic shifts in the western world and the effects of aging baby boomers on healthcare demands [3]. This segment is growing at around twice the rate of the general population and is projected to make up 20 % of the total US population by 2050 [4]. While life expectancy has risen steadily to an all-time high (81.1 years combined; 78.8 for women, 83.3 for men in Canada) [5], it should be appreciated that this peak is concurrent with compounding medical comorbidities. It is predicted that in the next 5–10 years, injured patients over the age of 60 will make up 50 % of the total visits to trauma centres [6].

The number of identified medical comorbidities increases with age [7]. Roughly 10 % of patients under the age of 19 exhibit multimorbidity, that is, more than one identified medical comorbidity. This number jumps to almost 80 % at age 80 in primary care patients [8]. Whether this number reflects the incidence of preexisting medical conditions in trauma patients is only starting to be appreciated. A recent study from Quebec looking at injured patients over the age of 65 admitted to a level I trauma center identified 57 % of patients with hypertension, 34 % with cardiac disease, 22 % with diabetes, and 22 % with dementia [9].

The old assumptions of a healthier, fitter older generation are set to change over the coming decades. Obesity rates in males over 75 years of age in the USA have doubled from 1988 to 2008. According to 2010 US census data, less than 12 % of people over 65 meet federally recommended activity guidelines [4]. What is now becoming clearer is the impact of other comorbidities on activity levels, with diabetes, Parkinson’s, and obesity being associated with increased levels of inactivity [7]. Injury patterns change with activity levels. Potentially high-energy injury mechanisms decrease as people drive less, or leave their residence less. As such, injuries from falls, such as closed head injury or hip fractures, predominate in this cohort.

Several preexisting medical comorbidity metrics have been developed in an attempt to quantify the significance of various diagnoses. The Charlson Index [10], and its derivatives, is a weighted scoring system to predict mortality over 10 years based on either a nurse-administered questionnaire or a patient self-reported form. Medical comorbidities can affect all aspects of the injury process, not just a given patient’s response after injury has occurred. We define a medical comorbidity as described by Elixhauser [11], as “… a clinical condition that exists before a patient’s admission to the hospital, … and is likely to be a significant factor influencing mortality and resource use.” For the purposes of trauma it makes sense to look at the effects of medical comorbidities across all phases of injury. For the purposes of this chapter, we consider these to include the pre-injury, injury, and recovery phases.


Pre-injury Phase


Over the past decades, injury prevention has moved to the forefront of our discussions of trauma burden. While issues like seatbelts, road safety, and helmet use have been extensively studied, risk reduction through optimizing care of chronic medical conditions is a new idea. Either the disease process itself or the injury related to these diseases may lead to decreased quality of life and disability; this may add another dimension to the discussions between healthcare providers and patients. The best studied of these medical conditions that predispose patients to injury are drug and alcohol dependence, and age-related cognitive and mobility changes. Others, like morbid obesity, which confers an increased risk of nonfatal injury [12], are only now being investigated, especially in the workplace [13], and in the elderly [14].


Chronic Alcohol and Drug Use


Excessive drinking, as is seen in chronic alcohol abuse, is the single most important risk factor for injury. Alcohol is a factor in 32.4 % of patient visits to trauma centers [15], and one-half of all alcohol-related deaths are from injury [16]. Recent initiatives to provide brief counseling to injured patients while in hospital as a method of reducing future injury events have been found to be both effective [17] and cost effective [18], and are being implemented in trauma centers across North America.

While illicit drug use rates have fallen in Canada over the past decade, young people aged 15–24 abused these drugs five times more than all other age cohorts. Worldwide, some 200,000 deaths per year are related to illicit drug use, with injury playing a major role [19]. Illicit drugs, however, represent only a portion of the total drug use. One-third of all prescription drugs used in the USA are by the elderly, who have on average more than five prescribed medications at a given time. The age cohort 50–65 currently uses the largest proportion of psychoactive prescription drugs, a number that could exceed illicit drug use [20]. It is projected that by 2020 up to a third of this age group will require drug dependency treatment as the rate of nonmedical use of prescription drugs increases [19]. There are also increased risks of injury with the use of non-psychotropic medications. For example, initiation of antihypertensive agents has been associated with increased fall risks [21].


Suicide Risk


Suicide is the eighth largest cause of death per year in some regions of the USA [22]; it is third largest cause of years of potential life lost, behind motor vehicle collision and violence, and accounts for 1.3 % of all deaths per year globally [23]. Preexisting depression, drug or alcohol abuse, and posttraumatic stress disorder are the major risk factors for suicide attempts or deaths [24, 25]. Suicide rates range around 11 % in drug-abusing youth populations. Only 1 in 25 suicide attempts by young people are successful, and the survivors represent a much larger burden on the healthcare system. Elderly greater than 75 have the highest suicide rates, with risk factors including serious physical illness and depression [26]. Increasing access to depression and drug addiction treatment for identified at-risk individuals has consistently shown decreases in suicide attempt rates [27].


Driving Risks


Age-related changes in cognition, reaction times, mobility, and vision are all important when performing medical assessments of older drivers. Legislation varies from region to region regarding which body determines fitness to drive, and the role physicians play. What is similar is the multimodal assessment across cognitive, medical, comorbid illness, and mobility scales [28]. Older drivers may be the safest age cohort in terms of absolute numbers, but contribute the most collisions per distance traveled.

These numbers are going to only increase, and by 2020 there are projected to be 40 million elderly drivers on US roads [29]; they are projected to be involved in one-sixth of all traffic collisions. There are often trade-offs to recommending a patient not to drive, and these can make the discussion difficult for some clinicians. Guidelines for physicians have been published by the American and Canadian Medical Associations; however adherence to them has not been universal.

Further, concerns over drivers of any age with significant medical comorbidities are valid, with US data indicating some 20,000 collisions per year linked to this group [30]. Relative risks of collisions are increased most with cardiovascular and neurologic diseases, and mental disorders. Other medical conditions, unrelated to age and polypharmacy use, may increase road traffic injury rates as well, though the literature is contradictory. Take for example obstructive sleep apnea, seen in as many as 45 % of obese people [31], with sleep deprivation a causative factor in roughly 20 % of all vehicle collisions [32].


Fall Risks


Falls represent the single largest mechanism of injury in the elderly. A third of older patients in the community fall per year, and half of those fall again soon after. Ten thousand elderly patients succumb to the consequences of falling annually in the USA [33], with an observed mortality rate in patients over 70 years old of 4 % after ground-level falls [34]. Nonfatal falls result in an inordinate number of fractures, though nonfatal head injuries are common as well. The cost burden from caring for these injuries is over $19 billion in the USA [33]. This segment is particularly at risk due to extrinsic and intrinsic factors. Examples of extrinsic factors are uneven flooring, poor footwear, inadequate lighting, and play less of a role as people age. Intrinsic factors are numerous, and worsen with age. Decreases in mobility, and fall avoidance mechanisms, in addition to the effects of polypharmacy are common. Add to this osteopenia or osteoporosis, which lessens the fracture threshold, and it is easy to understand the healthcare and economic burden falls have.


Injury Phase


Over the preceding decade, the culmination of changes to pre-hospital and initial resuscitation of trauma patients has led to reductions in early hemorrhagic deaths and those in the immediate ICU management [35]. This reduction in mortality however is not as successful in older patients or in those with preexisting medical conditions [36]. While these patients tend to suffer late consequences of their disease after the injury phase (see next section), there are considerations during their early trauma care that can aid recovery.

Leading a successful resuscitation strategy for a critically injured patient requires an understanding of the physiological response to shock, mechanisms, and methods of correcting coagulopathy, and knowledge of the risks and benefits of the various resuscitative measures. Medical comorbidities and the aging process can alter each of these aspects of trauma resuscitation, and when compounded may have dire consequences.

Hemorrhagic shock, the primary causative factor for early death from severe injury, leads to increasingly well-understood physiologic consequences. Reversal of these physiologic derangements and subsequent support until a patient’s homeostatic mechanisms resume are the goals of resuscitation. Once the limits of the innate physiologic response to hypovolemia are reached, shock ensues. The ability of a patient to tolerate a shock state, and the resuscitative measures themselves, may determine the amount of time a trauma team has to stop bleeding and restore homeostasis. The ability of a patient to tolerate these efforts often limits survivability of a given set of injuries.

The term “homeostenosis” describes the loss of physiologic reserve due to aging. While this is difficult to study in isolation apart from concomitant comorbid disease, there is consensus in the geriatric literature regarding the concept [37]. The idea of a physiologic precipice, one that once crossed leads to a disastrous outcome (death, cardiac arrest, etc.), has been put forward. As more of the available physiologic reserve is used just to maintain health while aging, less is available to overcome massive perturbations such as is seen in injury. One area requiring study is the impact of multimorbidity on homeostenosis in younger patients; perhaps the concept of frailty (discussed later) will address this issue.

Alterations in cardiopulmonary physiology due to medical comorbidities such as chronic chronic congestive heart failure (CHF), ischemic heart disease, or chronic lung disease greatly limit a patient’s shock tolerance. A study looking at the relationship of cardiac disease and trauma outcomes [38] found increases in mortality rates with CHF, pre-injury beta-blocker use, and warfarin use. For example, pre-injury CHF, when combined with significant chest injury, can lead to a fivefold increase in mortality rates over patients without CHF.

When looking at the isolated effects of single-drug agents on aspects of injury, there are a few points worth noting. Pre-injury beta-blocker use itself may not lead to increased mortality, though slower presenting heart rates and bradycardia may be seen during resuscitation [39]. With anticoagulants, the effects are clear, especially with closed head injuries [40]. Warfarin use prior to head injury does increase progression of disability and mortality. A protocol of early risk recognition, and reversal with vitamin K and plasma products, has been shown to mitigate this risk [41]. Using four factor (Factors II, VII, IX, and X) prothrombin concentrate has shown some initial promise [42] while potentially avoiding the difficulties of using large doses of plasma, including large-volume administration in a patient with tenuous cardiac physiology, blood-borne infections, and transfusion-associated lung injury (TRALI) [43]. Questions regarding thrombotic risk, duration of efficacy, and overall cost–benefit analysis between prothrombin concentrates and plasma products have yet to be conducted. Quite different from warfarin, anticoagulation reversal is more difficult with antiplatelet agents, especially aspirin and clopidogrel [44], and much more worrisome are the direct thrombin inhibitors, to which no expeditiously efficient reversal means exist [45, 46].

Given the changes in physiologic response due to aging, some have suggested changes in triage criteria [47] and increased use of intensive invasive [48] and noninvasive [49] monitoring in the elderly trauma population. As such, recent guidelines by various trauma associations recommend age criteria for trauma team activation, noting prior significant under triage, and increased mortality in patients >70 years of age.


Surgical Management Strategies of Severe Injury


In addition to changes in physiologic reserve associated with multimorbidity, aging, or use of medications, the specific management of certain injuries can differ also. Though now widely accepted in younger patients, non-operative management of significant liver and spleen injuries as the result of blunt trauma is more likely to fail in patients older than 55 years [50]. As well, mortality from these injuries is higher in elderly patients. There has been an evolution in the recommendations from various trauma associations regarding the exclusion criteria for non-operative management of blunt solid organ injury. Low thresholds for conversion to operative management for even brief episodes of hypotension [51], in the setting of intensive care monitoring, were shown to reduce the risk of mortality in these fragile elderly patients to the same levels as younger patients. The role of angioembolization as an alternative to surgery has not been well studied in these patients.

As discussed in Chaps. 14 and 15, damage control surgery (DCS) is now common practice and may be considered as a modality of trauma resuscitation. A recent trauma database review looking at DCS in patients over and under 55 years of age [52] indicates that although mortality rates are higher in the older cohort, significant numbers of these patients survive to discharge. Age alone is not a contraindication to performing DCS, and it should be included in the list of possible life-saving efforts.


Recovery Phase


Recovery from injury and return to the general population are probably most affected by comorbid disease and age. At best, the patient is left with their preexisting illness and infirmity. Commonly, though, recovery and rehabilitation periods in these patients are protracted, limited, and fraught with complications.


Outcomes After Injury


Perhaps the best studied aspect of trauma care with patients with medical comorbidities is outcomes. As more effective trauma systems were developed over the later half of the last century, the causative factors of mortality changed. Early deaths from hemorrhagic shock have decreased dramatically as rapid pre-hospital transport developed, and early resuscitation strategies evolved. These great strides made in trauma care are in part due to the development of specialized trauma centers. Alarmingly though, these improvements are not seen in older adults when treated at the same specialized centers [53]. The nature of death after major trauma is now shifting; we are now seeing deaths occur later in the hospital stay in patients with preexisting medical comorbid disease.

Mortality increases with age and preexisting medical conditions across all levels of injury, but particularly in the intermediate injury severity range [54]. A clear doubling of the ISS-matched mortality rate for the elderly compared to younger adults has been shown [55]. Older patients seem to have a bimodal time distribution for death when compared to younger patients. Severely injured older patients tend to die earlier, during resuscitation, or if they survive this phase, later from complications of their comorbidities [56]. A small component of these early deaths may include a bias towards earlier withdrawal of care decisions, perhaps from those with advanced directives. The late deaths can be from causes completely unrelated to their presenting injuries.

Initial case–control studies have provided estimates of the contributions of various preexisting medical conditions on mortality after trauma [57]. Cirrhosis, congenital coagulopathy, coronary artery disease, chronic lung disease, and diabetes all seem to be implicated, with relative odds ranging from 1.2 to 4.5 in multiple regression models. However, the compound effects of these conditions are more difficult to tease out of retrospective studies. For example, outcomes for obese patients may be worse [58] or better (the protective “obesity effect”) depending on how studies control for chronic illnesses like diabetes and heart disease [31]. The same can be said for other studied comorbid diseases such as hypertension, heart disease, and diabetes. The effects of multimorbidity may impact mortality more in the “young old” (aged 50–65) for reasons that are unclear as of yet [9].


Fractures and Mortality


Perhaps best known is the increased risk of mortality with multimorbidity and age after hip fracture [59, 60]. What is interesting is how evenly distributed chance of dying is over the following 6 months, indicating the need for continuous vigilant care of preexisting medical conditions and providing aggressive physiotherapy services. Clearly, with respect to hip fractures, the real work of improving outcomes starts after operative management has been completed.


Delayed Complications and Mortality


For multisystem-injured patients, after surviving the initial resuscitative phase, there are also marked differences in the recovery courses between the elderly and younger adults, and patients with multimorbidity. This difference may be seen in patients as young as 45 years of age, after which significant differences can be seen in length of stay, end-organ and infectious complications [61], and disposition [9]. This echoes reports of increased morbidity following rib fractures above the age of 45 as well [62]. Moreover, delayed mortality from complications unrelated to injuries sustained has been demonstrated in patients over 65 years with preexisting medical conditions, with a peak past 13 days since admission [9].

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Oct 28, 2016 | Posted by in CRITICAL CARE | Comments Off on Medical Comorbidities and Trauma

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