Much was learned in the twentieth century about disease and how it presents in children and adults. Traditional medical teaching emphasizes specific disease symptoms and signs that point to a specific diagnosis. However, in the last several decades it has become apparent that common diseases often present differently in older adults. This has lead to the concept of so-called atypical disease presentation in older adults. The exact prevalence of atypical disease presentation in the elderly is unclear in the medical literature but some researchers report that as many as 50 percent or more of older adults, particularly those who are frail, primarily present with disease atypically.
As people age, many bodily changes occur, but two have major consequences for disease presentation. The first is the inevitable alterations that occur within the various body systems that represent normal physiological changes of aging. Many are unavoidable and alone do not fully explain why older adults often present atypically. However, some of these changes certainly set the stage for increased susceptibility both to illness and to the way in which the disease presents itself. A classic example is alteration in thermoregulation with age, so that many older people do not have a fever when infected. Other examples are the increased risk for hyperthermia, hypothermia as well as dehydration due primarily to the changes in the body's ability to control body temperature and detect thirst. These normal consequences of aging coupled with concomitant disease and medications often together help set the stage for atypical disease presentations.
The second change that occurs with aging is related to the pathophysiological changes associated with aging, or the accumulation of disease. Many of the most common diseases that affect people increase in frequency and severity as the body ages. The likelihood of developing major diseases such as heart disease, diabetes, osteoporosis, stroke, and dementia all increase with age.
Another evolving concept that contributes to atypical disease presentations in older adults is the syndrome of frailty, understood as a vulnerable state arising from multiple interacting medical and social problems. The syndrome of frailty is critical to the understanding of disease presentation in the older adult. It is the frail elderly who most often present atypically.
Traditional disease presentation
Learning how disease presents in adults is the cornerstone of traditional teaching of those in the medical profession and other health care professionals. Health care practitioners learn that each disease has a specific set of signs and symptoms and are trained to sort through all of this information to come up with the most likely diagnosis for each set of signs and symptoms. Different diseases are classified and subsequently taught according to the different body systems and the symptom complexes in which they present. Scanning any medical textbook would confirm this method of organization, as each chapter usually deals with different body systems and the diseases that affect it.
Using this model of diagnosis would suggest that if an older adult is having difficulty walking, the health care professional would most likely assume that the causative disease should be related to the bones, muscles, or nerves that allow them to walk. In this scenario an accurate diagnosis of a broken hip may be made using traditional diagnostic approaches. However, in the older frail adult the diagnosis could as easily be heart failure or influenza as a broken hip. This emphasizes the importance of the need for an understanding of atypical disease symptoms in older adults, particularly those who are frail.
Atypical disease presentation
The concept of atypical disease presentation has been described by many in the literature. The phrase geriatric giants has long been recognized and taught in geriatric medicine and refers to the usual way in which disease presents itself in aging individuals. The commonly cited geriatric giants include immobility, instabilty (falls), incontinence, and intellectual impairment. These four syndromes are often the way in which disease presents itself. Other terms have also been used to describe the way older adults present with disease and these include silent presentation and non-specific presentation.
Several studies conducted in the 1980s and 1990s have shown that atypical disease presentation may indeed be the most common type of disease presentation in the older adult. One study found that 36 percent of all elderly persons admitted to hospital presented atypically. When the population was stratified for frailty, 60 percent of those who were frail at the time of admission presented atypically, compared to 25 percent of those that were previously well. This emphasizes the interaction between frailty and atypical disease presentation.
Types of atypical disease presentation
The most common form of atypical disease presentation is with one or several of the geriatric giants listed above. It is important to recognize that one of the geriatric giants may be the presenting complaint but often many coexist. The key to recognizing the geriatric giants as a presentation of disease is to understand that a new appearance of a geriatric giant in an older individual is often a sign of a new illness. Likewise, a worsening of any of these giants equally signifies a problem worthy of assessment. Therefore, it is important to understand how an older person was functioning when they were well in order to notice the new onset of a geriatric giant or worsening of one.
Understanding an individual's level of function is key to understanding the importance of the geriatric giants for picking up disease in older adults. An older person may have difficulties getting around inside and outside their home due to underlying diseases such as osteoarthritis and require a walker. This may be their normal level of function. However, if this same individual is now unable to get up from bed and stand this should indicate that something is wrong and should be considered an atypical presentation of some disease (immobility).
Likewise, when an individual begins to fall (instability) for no apparent reason, the body may be saying that it is sick and this may be the way in which an acute illness is presenting. A new onset of incontinence (either urinary or fecal) is often a marker of an underlying recent illness that also deserves attention.
Acute confusion in an older person is nearly always associated with a new underlying illness. An illness presenting this way would be presenting as one of the geriatric giants-intellectual impairment. In medical terminology this is referred to as delirium, which is an acute change in cognition often associated with inattention. Dementia is also a cause for intellectual impairment but is chronic in nature and slowly progressive. Those with an underlying diagnosis of dementia are at increased risk of developing delirium if ill for any reason.
Any change in an individual's normal level of function requires consideration in order to rule out any possible new illness that may be contributing to the problem. It was found in one study that delirium was the most common form of an atypical disease presentation, being the presenting symptom in 50 percent of those presenting atypically. Falls and immobility combined accounted for 21 percent of the atypical presentations and nonspecific functional decline for another 20 percent.
Implications of atypical disease presentation
While atypical disease presentation may indeed be the norm for older frail adults presenting with disease, the implications of this type of presentation are less well understood. Those adults who present atypically tend to do worse in terms of adverse hospital outcomes, particularly in terms of admission to long-term care facilities following discharge from an acute care hospital. They are more often restrained in hospital, given nighttime sedation, and wind up with pressure ulcers than those who present typically. These older adults, particularly those who are frail, tend to have a poorer prognosis than those who present with typical disease symptoms.
Differential diagnosis of atypical disease presentations
The differential diagnosis of atypical disease presentations in older adults is as encompassing as the entire spectrum of medicine. Virtually any disease, either acute or the worsening of a chronic illness, may be the precipitating cause for any atypical disease presentation in an older adult. However, there are a few common illnesses that account for the majority of these cases. The more common illnesses to consider would be:
- Infection (urinary, pneumonia, sepsis, other)
- Ischemic heart disease (congestive heart failure, myocardial infarction, other)
- Medications (alcohol, prescription and non-prescription)
- Metabolic abnormalities (dehydration, electrolyte imbalance, other)
This is by no means meant to be an exhaustive list but will certainly assist in formulating a management plan for further assessment and subsequent treatment for these individuals. Investigations targeted to identify these common causes of disease in the elderly will yield positive results the majority of the time.
The management of elderly patients who present with atypical disease presentations begins with initial recognition of their illness. All too often recognition that the person is sick goes unnoticed. It is not uncommon for health care providers, patients, and their families to attribute some of the symptoms as synonymous with aging, and they may not even seek medical attention. It is of paramount importance to recognize when illness is present and to seek medical attention. It is then the responsibility of the health care providers to recognize this call for help, investigate appropriately, and treat reversible causes.
It is important to target investigations in order to identify the most common cause for the atypical presentation of an illness. Simple investigations including blood work, cultures, and x-rays are often invaluable in pinpointing a cause. It is also important to review all medications that the individual is taking including prescription drugs, over-the-counter preparations, and alcohol use. Inquiring about compliance with medications is also prudent, because missing some medications or taking too many of an other can equally be the cause of the atypical disease presentation. Once the cause is found, appropriate medical management can proceed.
Of paramount importance in the treatment of older, frail adults, particularly in hospital, is appropriate treatment strategies to prevent further complications of hospitalization. It is well known that elderly adults, once hospitalized, are at increased risk of complications from both the treatment as well as bed rest. It is important to be cognizant of this and promote early mobilization, adequate nutrition, and appropriate maintenance of physical functioning to try to avoid these complications.
Atypical disease presentation in older adults is very common and in fact is the most common presentation of illness in the frail older adult. It is merely the body's way of indicating that it is unwell and that it requires attention and treatment. The underlying cause for these disease presentations is often a common medical problem such as infection, congestive heart failure, or medications (too much or too little). A comprehensive review of a person's medical history and functional history is required along with a detailed review of all medications. Targeted investigations will often reveal the underlying cause and treatment of this is often successful. However, older adults presenting with atypical disease presentations may have poorer health outcomes then those who present with typical disease symptoms. The understanding that disease presents differently in older adults is one of the main reasons why specialties such as geriatric medicine and geriatric psychiatry have evolved into the disciplines that they are today.
Pamela G. Jarrett, M.D., F.R.C.P.C.
See also Assessment; Balance and Mobility; Delirium; Emergency Room; Fluid Balance; Frailty; Heart Disease; Pneumonia; Swallowing; Urinary Incontinence.
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