Expectancy and Assessment of Functional Status in Older Adults

Fig. 2.1

Number of persons 65+, 1900 to 2060 (number of millions). (Source: U.S Census Bureau, Population Estimates and Projections publically available at https://www.acl.gov/aging-and-disability-in-america/data-and-research/profile-older-americans)

As the number of older adults continues to grow, trauma centers will experience an increase in the number of older patients that they treat. Compared to younger patients with similar injuries, older patients tend to have worse outcomes following surgery, which can be attributed, in large part, to preexisting comorbidity and disability. As many as two-thirds of older adults have two or more chronic conditions, [3] and according to the 2013 Medicare Current Beneficiary Survey, 30% of non-institutionalized beneficiaries reported difficulty in performing one or more activities of daily living (ADLs), which include bathing, dressing, eating, and getting around the house. An additional 12% reported difficulty with one or more instrumental activities (IADLs), which include preparing meals, shopping, managing money, using the telephone, doing housework, and taking medication [1].

Despite declines in overall function with age, there is notable heterogeneity in health and activity among older adults. According to data from the 2012–2014 National Health Interview Survey (NHS), 44% of non-institutionalized older adults reported excellent or very good health and many continue to participate in moderate-intensity physical activity even late in life. The 2001 Behavioral Risk Factor Surveillance System survey (BRFSS) found that only 21% of adults aged 65–74 were inactive based on measures of occupational, household, and leisure time physical activity, while 34% engaged in moderate activity and 18% engaged in vigorous activity. These percentages are slightly lower among adults 75 years and older, but even in this age group, 29% were engaging in moderate activity on a regular basis [4]. Another study using data from the 2001 NHS showed similar results—26.1% of older adults participate in regular light to moderate or vigorous aerobic activity [5]. Participation in the labor force is another marker of activity and many older adults are employed. The Bureau of Labor Statistics estimated that 8.8 million Americans 65 years or older were working or actively seeking work in 2015. This constitutes 5.6% of the labor force. In both men and women, the percentage of older adults that participate in the labor force has increased over the past 30 years (16–20% in men and 10% in women) [1]. With the expected growth of the aging population, these percentages are likely to rise.

There is growing evidence for a distinction between the third and fourth ages as supported by trends in disability and function. The third age (i.e., “the young old”) is characterized by increases in life expectancy, better physical and mental fitness, and high levels of emotional and personal well-being. Data from several longitudinal studies suggest that 70-year-olds today are comparable to 65-year-olds who lived 30 years ago. In general, the “young old” have fewer physical disabilities (e.g., ADL and IADL disability) than earlier cohorts, [6] and in fact some studies reported an annual decline in overall disability and functional limitation between 1990 and 2000 ranging from −1.52% to −0.92% [7]. Individuals who have reached old age over the past two decades have benefited from advances in medical care, improved economic situations, better education, and more psychological resources. These improvements in quality of life have no doubt contributed to overall well-being [6]. Unfortunately, these trends do not persist in the fourth age (i.e., “the oldest old”). The fourth age is characterized by prevalent dementia and high levels of multi-morbidity, physiologic dysfunction, and frailty. In developed countries, on average, individuals transition into the fourth age when they reach 85 years. However, this is a population-based threshold and the transition may actually vary quite a bit among individuals depending on a host of health and environmental factors. In other words, older adults can and do maintain good health and function well into their 80s.

Given the heterogeneity in health and function among older adults, age alone is not necessarily the best predictor of outcomes following surgery. There is growing evidence to support the use of frailty measures to identify older patients at risk of poor outcomes which may better inform treatment decisions. This chapter discusses the utility of frailty measures in older adults undergoing surgery. In addition, this chapter discusses the validated measures of physical performance that can be used to evaluate recovery and outcomes following surgery in older adults.

Frailty in Older Adults

Frailty is a clinical condition that results in loss of physiologic reserve and predisposes individuals to adverse health outcomes including death. While there is overlap with disability and comorbidity, frailty is considered a distinct clinical syndrome associated with increased vulnerability and functional impairment under minimal stress [8]. Because of the implications for clinical care, it is important to screen for frailty in older adults, particularly those undergoing surgery as they are more likely to have adverse outcomes if frailty also exists. Frail patients undergoing surgery may require alternative approaches to standard of care. If there are multiple options for surgical treatment, the less aggressive approach may yield better outcomes. Similarly, frail patients may do better if cared for by a multidisciplinary team that facilitates pain management and rehabilitation following surgery. A study by Markary et al. of approximately 600 older patients undergoing elective surgery found that intermediately frail patients were more likely to experience 30-day postoperative complications (odds ratio = 2.06; 95% CI 1.18–3.60), longer lengths of stay (by 44–53%), and were more likely to be discharged to a skilled nursing facility (odds ratio = 3.16; 95%CI: 1.9.99). Outcomes were worse in frail patients. This study showed that frailty independently predicted outcomes when compared with other commonly used risk measures including the American Society of Anesthesia (ASA) score [9]. The ASA score is a clinical assessment of an individual’s physical health with scores ranging from 1 (a normal healthy patient) to 5 (moribund patient not expected to survive without operation) [10]. While this is a quick and easy way to assess physical status prior to surgery, it may not distinguish subtle differences in function among older adults the way that a measure of frailty can. In fact, several studies have shown that measures of frailty are better predictors of mortality among older adults undergoing surgery than ASA alone [11–13].

While there is no gold standard operational definition of frailty, two widely adopted approaches have influenced a number of frailty assessments. The seminal work by Fried et al. defined the frailty “phenotype” as the occurrence of at least three of five components: unintended weight loss, weakness, exhaustion, slowness, and low activity (Table 2.1). This model is based on the theoretical cycle of frailty that suggests that there are different pathways through which frailty can impact the dysregulation of multiple physiologic systems [14]. Based on this model, individuals are considered frail if three or more of these criteria are present and pre-frail if one or two criteria are met. The frailty phenotype has been associated with morbidity, ADL disability, hospitalization, and death in community dwelling older adults even after adjusting for other measures of health, disease, depression, and disability [14–17].

Table 2.1

Frailty phenotype [8, 14]

Weight loss	Unintended weight loss of 10 pounds in past year or weight at examination ≤10% of weight at age 60
Exhaustion	Self-reported fatigue or unusual tiredness or weakness in past month
Low activity	Frequency and duration of physical activities (walking, doing strenuous household chores, doing strenuous outdoor chores, dancing, bowling, and exercise)
Slowness	Walking 4 m ≥ 7 s if height ≤ 159 cm or ≥ 6 s if height ≥ 159 cm
Weakness	Grip strength (kg) for body mass index (kg/m²)

The second approach is a deficit accumulation model proposed by Rockwood, which defines frailty as the total number of deficits that an individual has from 70 clinically recognizable variables including comorbidities, measures of disability, and dementia [18] (Table 2.2). These items are common in routine geriatric assessments. A frailty index can be computed by adding the number of deficits and dividing by the total number possible. For example, a person with five deficits would have an index score of 5/70 = 0.07. The model posits that the deficit accumulation is the basis for the loss in physiologic reserve underlying frailty. In this approach, the number of deficits rather than the type of deficit is important—the more deficits a person accumulates, the higher their risk for adverse outcomes. Using data from the Canadian Study of Health and Aging, Rockwood demonstrated that the frailty index was associated with greater likelihood of death and institutionalization. The clinical frailty scale (CFS) is an extension of this work that measures frailty based on clinical judgement (Table 2.3). The CFS places individuals into one of seven frailty categories based on clinical evaluation and performed just as well as the frailty index in terms of identifying at-risk individuals [19].

Table 2.2

List of variables in the 70-item frailty index [19]

Changes in everyday activities

Head and neck problems

Poor muscle tone in neck

Bradykinesia, facial

Problems getting dressed

Problems with bathing

Problems carrying out personal grooming

Urinary incontinence

Toileting problems

Bulk difficulties

Rectal problems

Gastrointestinal problems

Problems cooking

Sucking problems

Problems going out alone

Impaired mobility

Musculoskeletal problems

Bradykinesia of the limbs

Poor muscle tone in the limbs

Poor limb coordination

Poor coordination, trunk

Poor standing posture

Irregular gait pattern

Falls

Mood problems

Feeling sad, blue, depressed

History of depressed mood

Tiredness all the time

Depression (clinical impression)

Sleep changes

Restlessness

Memory changes

Short-term memory impairment

Long-term memory impairment

Changes in general mental function

Onset of cognitive symptoms

Clouding or delirium

Paranoid features

History relevant to cognitive impairment or loss

Impaired vibration

Tremor at rest

Postural tremor

Intentional tremor

History of Parkinson’s disease

Family history of degenerative disease

Seizures, partial complex

Seizures, generalized

Syncope or blackouts

Headache

Cerebrovascular problems

History of stroke

History of diabetes mellitus

Arterial hypertension

Peripheral pulses

Cardiac problems

Myocardial infarction

Arrhythmia

Congestive heart failure

Lung problems

Respiratory problems

History of thyroid disease

Thyroid problems

Skin problems

Malignant disease

Breast problems

Abdominal problems

Presence of snout reflex

Presence of the palmomental reflex

Other medical histories

Table 2.3

Clinical frailty scale [19]

1. Very fit	Robust, active, energetic, well motivated and fit; these people commonly exercise regularly and are in the most fit group for their age
2. Well	Without active disease, but less fit than people in category 1
3. Well, with treated comorbid disease	Disease symptoms are well controlled compared with those in category 4
4. Apparently vulnerable	Although not frankly dependent, these people commonly complain of being “slowed up” or have disease symptoms
5. Mildly frail	With limited dependence on others for instrumental activities of daily living
6. Moderately frail	Help is needed with both instrumental and non-instrumental activities of daily living
7. Severely frail	Completely dependent on others for activities of daily living, or terminally ill

Assessing for Frailty in Older Patients Undergoing Surgery

A recent systematic review of the literature identified 32 unique frailty assessment tools that have been applied in older adult patients undergoing surgery. Some of these tools draw directly from the Fried and Rockwood approaches while others combine well-validated measures of cognition, function, comorbidity, and disability [20]. The review identifies instruments that are objective, feasible, and useful for this patient population. One of the instruments meeting these criteria is the electronic frailty model. Amrock et al. proposed an electronic medical record-based model to approximate a measure of frailty in older patients undergoing colorectal surgery. The model included measures of chronic inflammation and sarcopenia that are indicative of the physiologic dysregulation associated with frailty. These measures were body mass index (BMI), preoperative measures of serum albumin, hematocrit, serum creatinine, and Anesthesiologist Physical Status Score (ASA PS).²¹ In a retrospective evaluation of medical record data, the investigators found that individuals with BMI <18, serum albumin <3.4 g/dL, hematocrit <35%, serum creatinine >2 mg/dL, and ASA PS score of IV had a significantly increased risk of 30-day mortality and major postsurgical morbidity (i.e., cardiac arrest, myocardial infarction (MI), pneumonia, pulmonary embolism (PE), reintubation, renal insufficiency, infection, sepsis, deep vein thrombosis (DVT), and reoperation) [21]. This study demonstrates that clinical measures approximating frailty which can easily be obtained from the EMR are associated with poor outcomes.

Another frailty measure with practical utility is the modified frailty index (mFI), Rockwood’s 70-item frailty index was pared down to 11 items and evaluated among older patients undergoing emergency general surgery. The frailty index was chosen because it was adaptable to an acute care setting unlike the Fried model where gait speed and strength cannot easily be measured. The modified frailty index included history of (1) diabetes mellitus, (2) congestive heart failure, (3) hypertension requiring medication, (4) transient ischemic attack or cerebrovascular accident, (5) myocardial infarction, (6) peripheral vascular disease or rest pain, (7) cerebrovascular accident with neurological deficit, (8) chronic obstructive pulmonary disease or pneumonia, (9) prior percutaneous coronary intervention, prior cardiac surgery or angina, (10) impaired sensorium, or (11) not independent. Using data from the Surgeons National Surgical Quality Improvement Program (NSQIP), Farhat et al. found a positive association between frailty index, mortality, and infection. The more the items present, the greater the risk of 30-day mortality and infection. In this study, the frailty index was a stronger predictor of outcomes compared with age and ASA score [13].

In a retrospective study of low-energy femoral neck fractures in adults 60 years or older, 19 of the 70 frailty index items were used to create a modified index (Table 2.4). The 19 items were selected for this patient population based on their likelihood of being documented in the admission notes and their ease in being administered in the emergency room for future applications [22]. The study found that their version of the modified frailty index was associated with one- and two-year mortalities. Percent mortality increased with each increase in frailty index score. Patients with a modified index of 4 or greater had significantly higher odds of death compared with patients with a lower index. Having this information available at time of admission for older patients undergoing surgery may impact treatment choice. For example, patients with an index below 4 and a survival rate of 90% in the first year following fracture may be able to withstand and benefit from more aggressive surgical treatment. The frailty index may also alter a patient’s care pathway. Patients with a higher index may do better if admitted to a medical service rather than an orthopedic service with a focus on non-opioid pain management, physical therapy, and more interaction with primary care [22].

Table 2.4

Modified frailty index [22]

Cerebrovascular accident or transient ischemic attack

Impaired cognition (dementia, Alzheimer’s)

History of recurrent falls

Diabetes mellitus (except diet-controlled diabetes)

History of syncope or blackouts

Ambulation—no assistive device

Ambulation—with walker or cane

Non-ambulatory or use of scooter/wheelchair

Psychotic disorder (posttraumatic stress syndrome, bipolar disease, paranoia, schizophrenia)

Thyroid disease

History of seizures

Congestive heart failure

Depression

History of malignancy

Decubitus ulcer

Cardiac disease (coronary artery disease, arrhythmia mitral valve prolapse, aortic stenosis)

Urinary incontinence

Parkinson’s disease

Renal disease (acute or chronic)

Respiratory problems (COPD, emphysema, OSA, chronic bronchitis)

History of myocardial infarction

Although many screening tools are available to assess for frailty in older patients undergoing elective surgery, there is little information on clinically useful assessments for older trauma patients. Evaluation of these patients is complicated because tests like gait speed, a critical component of the frailty phenotype, are not feasible to complete prior to emergency surgery and are likely affected by the patient’s condition (i.e., injury). This is a relatively new area of research and more work need to be done to establish meaningful thresholds using existing frailty measures and their components and to refine and validate new measures appropriate for this patient population. It will also be important to select measures that can easily be implemented in the acute trauma setting prior to surgical treatment for an orthopedic injury. For example, two studies evaluated the use of a modified frailty index among patients undergoing surgery for hip fracture repair. The assessment required an interview with the patient or the patient’s caregiver and only took 5–10 minutes to administer [11, 23]. However, the ease with which a frailty assessment is administered will depend on the number of items included and, to some extent, staff expertise. Most of these items can be drawn directly from a comprehensive geriatric assessment that may or may not be conducted as standard practice in the trauma setting. In the absence of a comprehensive assessment, clinicians will need to incorporate these evaluations and be able to score them into their workflow. The addition of a cognitive evaluation adds another layer of logistical complexity. The frailty score evaluated by Robinson et al. across different surgical specialties includes a mini cognition assessment that uses a three-item recall and clock-drawing task [24]. While frailty and dementia are closely intertwined, cognitive assessment may be difficult to administer in the acute setting. Although there is more work to be done to identify the best measures of frailty for patients undergoing surgery, the literature reviewed here provide a foundation and starting point for assessing function and improving risk stratification in older patients where age is not a reliable predictor of outcomes.

Measures for Evaluating Physical Function in Older Adults

Return to function is an important outcome following surgery, especially in older adult patients. Periods of prolonged non-weight bearing can have deleterious effects on overall recovery and function [25]. Function can be measured using self-reported assessments or with objective measures of physical performance. While both measure similar aspects of function, performance measures offer some advantages over self—report in terms of validity, reproducibility, sensitivity to change, their applicability across different populations and studies, and their ability to characterize higher levels of function [26]. Performance measures alone or in combination with self-report are better predictors of health outcomes such as hospitalization, death, decline in health status, and disability when compared with self-reported measures alone [27]. While they may incur some additional costs in terms of staff time and resources (i.e., adequate clinic space), performance measures provide an objective means of quantifying function among older adults.

Interestingly, performance-based and self-reported measures of function were found to be comparable with respect to their sensitivity to change in patients following hip fracture [28]. This suggests that in some situations such as recovery from a severe orthopedic injury, performance measures may provide information that is distinct from self-report. Meaningful change following a fracture may be contextually different than meaningful change in an average-functioning population. For example, an individual may experience significant improvement in gait speed during recovery from a fracture but may not perceive their improvement as substantial in light of limitations in other areas of function that they value in everyday life (i.e., climbing stairs and going out to the store). The measures discussed in this section highlight the validated assessments of physical performance that have been widely studied in older adults and are easy to implement in the clinic. Further, the criteria that have been established for meaningful changes for many of these measures can help clinicians evaluate recovery progress following treatment or design research studies that will detect clinically meaningful differences in function.

Perhaps the easiest to assess is gait speed. Individuals are timed in walking a certain distance (usually 4 or 10 m) at their usual pace. In healthy older adults, average gait speed is 0.7–0.9 meters per second (m/s) [28]. Slow gait speed has been associated with disability, hospitalization, and mortality even after adjusting for age and health status [29–32]. Other measures of mobility include the 6-meter walk test (6 MW) and the timed up and go (TUG). The 6 MW test is an endurance measure that assesses the distance a person can walk on a measured walkway for 6 minutes. The 6 MW has not only been used primarily to predict mortality and morbidity in patients with cardiovascular disease [33], but it has also been used to evaluate outcomes after hip fracture [28]. On average, older men and women are able to walk for a longer distance 12 weeks following hip fracture repair compared with the distance they were able to walk just 2 weeks following surgery (251 m vs. 121 m) [28]. These data come from a randomized controlled trial testing the effects of a drug to prevent muscle wasting following hip fracture repair among older patients living independently and who were at least partially weight-bearing 2 weeks following surgery. In this study, the 6 MW distance was positively correlated with other measures of gait speed and it was significantly associated with self-reported function—individuals who were able to walk longer distances reported better overall function. As may be expected, walking distance was adversely affected by leg pain and use of assistive devices [28].

The timed up and go (TUG) measures the time a person takes to stand from a chair, walk 3 m, turn and walk back to the chair, and sit down. It was originally developed as a measure of balance [34] but is now used as a test of basic mobility [35] and has been shown to predict postoperative morbidity and mortality among older adults following surgery across multiple surgical specialties [36]. In a study of approximately 200 patients 65 years or older undergoing elective colorectal (n = 98) and cardiac operations (n = 174), slow times on the TUG taken within 30 days prior to surgery were significantly associated with one or more postoperative complications, institutionalization, and higher 1-year mortality [36]. Individuals with a slow TUG time (≥15 s) were older, had impaired cognition, and more disability in activities of daily living [36]. While this study used the TUG as a screening tool for poor outcomes, it can also be used to evaluate changes in function following surgery.

While gait speed is a reliable predictor of outcomes, the short physical performance battery (SPPB) may provide additional information about function that gait speed cannot. Specifically, it may discriminate among higher functioning older adults with fast gait speed. The SPPB is a valid measure characterizing older adults across a broad spectrum of lower extremity function and, like gait speed, it independently predicts disability, mortality, and institutionalization [26, 27]. Individuals are scored on a scale ranging from 0 (worst performance) to 12 (best performance) based on their walking speed, ability to do chair stands, and standing balance. Walking speed is determined by measuring the time individuals take to walk 8 feet at their normal pace. Assistive devices can be used if necessary. To complete chair stands, individuals are asked to stand from a sitting position on a straight backed chair with arms folded across the chest. If standing can be achieved, individuals are asked to repeat five consecutive times as quickly as possible and are timed from the initial sitting to the final standing at the end of the fifth stand. Standing balance tests include tandem, semi-tandem, and side-by-side stances. Timing is stopped when individuals move their feet, reach out for balance, or after 10 s. Individuals are first asked to hold a semi-tandem stance with the heel of one foot placed to the side of the first toe of the other foot. If unable to hold this position, individuals are timed with feet side by side. If individuals are able to hold a semi-tandem stance, they go on to balance in a full tandem position with heel of one foot directly in front of the toe on the other foot. For walking speed and chair stands, a score of 0 is assigned if unable to complete, and among individuals who can complete the tests, scores are based on quartiles of speed where 1 represented the slowest and 4 the fastest time. For balance, scores are assigned based on ability to balance in semi-tandem and tandem stands (see Table 2.4). A score of 0 is assigned if unable to hold semi-tandem balance for at least 1 s or unable to hold side-by-side stance for 10 s. A score of 1 is assigned if an individual can hold the semi-tandem stance for 0–9 s or the side-by-side stance for 10 s. Scores of 2–4 are assigned based on the balance time for the full-tandem stance among individuals who can complete the semi-tandem stance [26].

Estimates of meaningful change in the SPPB, gait speed across multiple distances, and the 6 MW test are presented in Table 2.5. The first set of estimates use data from populations of community-dwelling older adults with mild to moderate mobility [37]. Estimates from two studies looking at meaningful change in gait speed among patients with hip fracture are summarized in the second and third columns of the table [38, 39]. All three studies use distribution-based methods to compute estimates of meaningful change. These methods use the standard deviation of the measure (i.e., gait speed and SPPB) to estimate small and large differences based on standard effect sizes [37, 40]. With respect to gait speed, the estimates reported for a sample of community-dwelling older adults and the estimates reported by Alley et al. for a sample of women 12 month following hip fracture were comparable. This means that individuals who improve their gait speed by at least 0.10 m/s have experienced a clinically important change. While a change of 0.10 m/s has consistently been reported across different groups of older adults, it should be applied with caution. Alley et al. showed that meaningful change may actually be much larger in individuals with hip fracture when using anchor-based rather than distribution-based methods of analysis. Anchor-based methods compute estimates of meaningful change based on changes in self-reported function. When using improvements in self-reported function as an anchor, meaningful changes in gait speed the year following fracture ranged from 0.17 to 0.26 m/s [38]. Interestingly, Latham et al. reported similar estimates of change—0.17 m/s in the first 12 weeks following hip fracture—but using distribution-based methods [28]. The differences in these estimates may be attributed to the difference in samples (i.e., men and women participating in a drug trial to prevent muscle wasting following hip fracture versus older women participating in a trial testing an exercise intervention following hip fracture) and the time frame in which change was measured (i.e., 12 weeks following fracture versus 1 year following fracture). Latham also reported meaningful change in the SPPB and in the 6MWT, which were greater than the changes observed in community-dwelling older adults. These results suggest that meaningful change is context specific and likely depends on many factors including the population of interest and an individual’s perception of their function and limitations (Table 2.6).

Table 2.5

Scoring based on the Short Physical Performance Battery (SPPB) [26]

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