Introduction

With an ever burgeoning older population, the elderly will be a large part of the surgeon’s practice. Interestingly, the attitude toward geriatric surgery has changed over the years. A threshold of 50 years was chosen to describe geriatric patients in a paper in 1907 [1], and 20 years later influential surgeons still wrote that elective herniorrhaphy in this age group was not warranted [2]. Today, many complex operations are successfully performed in octogenarians, nonagenarians, and even centenarians [3–5].

In 2010, over a third of inpatient procedures in the US were performed in patients 65 years and older [6]. This number is projected to rise as the population continues to live longer. With this increase in age also comes a range of comorbidities such as cataracts, recurrent cancers, and coronary artery disease—the frequency of which in the latter years of life exponentially increases. Beyond these comorbidities it has been shown that aging presents unique challenges that must be considered when contemplating surgical options.

When viewing the challenges associated with aging, frailty emerges as one of the more exigent “phenotypic expressions” in the older population. Frailty is an age-related attenuation in multiple physiologic systems, culminating in greater susceptibility to minor stressors which can abruptly compromise an individual’s health. In other words, it is a vulnerable circumstance in which a “stressor event” causes a reduced likelihood of returning to homeostasis and an increased probability of encountering further “adverse outcomes.” The literature has repeatedly supported the association of frailty with poor health outcomes. Hence, frailty is becoming an indispensable part of a preoperative assessment in the older surgical patient.

Frailty Overview

Perioperative Frailty is Associated with Poor Surgical Outcomes

Although the concept of frailty has existed for a long time, its discussion in the medical literature has increased over the last three decades [7]. Since then three landmark studies have impacted our understanding of frailty and its association with suboptimal surgical outcomes. Dasgupta et al. found an association between high frailty scores (Edmonton Frail Scale) and increased postoperative complications [8]. Robinson et al. reported patients with increased frailty characteristics to have higher 6-month mortality [9]. Makary et al. described an association between frailty and increased postoperative complications [10]. Further examples of factors associated with frailty and subsequent poor surgical outcomes include prolonged length of stay, hospital readmission and discharge to institutional care facility (Table 1).

Table 1 Factors associated with frailty and poor surgical outcomes
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The advances in an ever-improving evidence-based framework with regard to frailty guide its use in perioperative management and risk stratification. In an effort to bridge the gap between the concept of frailty and its ramifications on surgical decisions and outcomes, the National Institute on Aging and the American Geriatrics Society sponsored a 2-day conference (March 2015) to discuss frailty and its implications in perioperative management [11]. Ultimately, comprehensive geriatric preoperative assessments help identify frail patients early and allow for a more comprehensive preoperative workup and preparation for surgery [12].

Frailty Defined

In 1908, Eli Metchnikoff posited, “How can we transform to a normal and physiological condition, old age, at present utterly pathological, unless we first understand the intimate details of its mechanism?” [13]. Currently, when viewing frailty in terms of “intimate” biologic underpinnings, examples of phenotypic expressions of frailty include telomere attrition, mitochondrial dysfunction, and epigenetic alterations [14].

Consensus opinion conceptualizes frailty as a multifaceted, age-related state of reduced multi-system, physiologic reserve causing increased susceptibility to stressors and decreased adaptive capacity [15–19]. The increased susceptibility to poor health outcomes include functional dependence, falls, mortality, and need for institutionalization [20]. Further, this “frail state” is associated with biologic rather than chronologic age.

While there is agreement on the concept of frailty no consensus has yet been established of how to best assess frailty [15]. A broad heterogeneous spectrum of tools has been developed in an attempt to quantify frailty’s operational definition. With differing measures of quantification, different operational definitions of frailty have emerged. The two most commonly cited are Fried’s phenotypic approach and the accumulation of deficit models by Mitnitski and Rockwood [17, 21, 22].

Fried’s phenotypic definition, also known as “physical frailty,” describes frailty as the consequence of phenotypic expression of the accumulated decline of multiple physiologic mechanisms. Frailty characteristics include unintentional weight loss, decreased muscle strength, self-reported exhaustion, low physical activity, and slow walking speed [17].

The accumulation of deficits model, also known as “frailty index,” defines frailty as a generalized, age-associated susceptibility exhibited by accumulated deficits entailing medical, social, and functional variables [23]. These deficits are quantified by medical diagnoses, symptoms, and lab abnormalities which are associated with increasing age and suboptimal health outcomes [24]. With this quantification Mitnitski showed a 3 % rate of deficit accumulation per year in community-dwelling individuals [25]. Kulminski et al. associated the frailty index with increasing age and mortality [26].

Considering these two theories of operational frailty the important difference is that phenotypic frailty is “driven” by biologic factors while the accumulation of deficit model is driven by an accretion of clinical deficits. Although there is general consensus on the conceptualization of frailty, no explicit consensus exists as to the most appropriate quantitative measure of operational frailty (that is clinically implementable and able to guide prevention and care) [15].

Frailty Quantified

A review of the literature reveals over 80 tools available to quantify frailty. Some “tools” examine over 60–70 items in an effort to quantify frailty. This reflects the multifaceted nature of variables illustrating the clinical needs for different specialties. Although this wide variety exists and despite differing opinions on frailty quantification tools, most experts agree that patients over age 70 should be screened for frailty. This is in agreement with the literature which supports interventions targeted towards the geriatric surgical population to ameliorate their frailty-associated adverse outcomes [27].

It is worthwhile to point out frailty screening and frailty assessments have differing purposes. Frailty screening is aimed at risk stratification. A frailty assessment provides a detailed formal evaluation to help define preoperative interventions to optimize surgical outcomes.

Frailty screening is often easily completed with single variable assessments such as Timed Get Up and Go Test and gait speed [28, 29]. Savva et al. showed that the Timed Get Up and Go Test could identify frail members of the older population [30]. In cardiac patients Afillalo et al. showed slower gait speed associated with increased postcardiac surgery morbidity and mortality [31].

Another screening tool often used is Frail Scale which takes less than 5 min to complete. It was developed by the Geriatric Advisory Panel of the International Academy of Nutrition and Aging in an effort to create a screening tool [29]. This tool reviews five simple questions quantifying frailty as robust, prefrail, and frail [32, 33].

Phenotypic frailty requires 10–15 min to complete, it is most commonly used in frailty research [17]. A diagnosis of frailty is made when three or more of the following five criteria are present: unintentional weight loss of 10 lb or more in the past year, self-reported exhaustion, weakness as measured by grip strength using a dynamometer, slow walking or gait speed, and low physical activity. The presence of two or three of these criteria would identify a person as “pre-frail.”

The deficit accumulation definition of frailty is quantified by criteria developed by Rockwood et al. in the Canadian Health and Aging Study [34]. Generally measuring between 21 and 70 deficits, the quantification is based on an index score which divides an individual’s number of deficits by the total number of measured characteristics. This test is more time consuming than aforementioned tests.

Perioperative Frailty and Closely Related Factors

Frailty and Resilience

A discussion of frailty would be incomplete without discussing resilience. Frailty and resilience are related, however not considered opposites. Resilience reflects an individual’s aptitude in dealing with stressors and challenges [35]. While resilience is not considered an opposite of frailty, it reflects an individual’s positive capacity in dealing with challenging events [14]. It is possible that the processes influencing frailty and resilience are closely entwined and reflected in genetic, environmental, and functional processes. More research is needed to assess whether quantifying “positive biologic reserve” will possibly improve surgical decisions and patient outcomes [35].

Frailty and Multi-Morbidity

It is important to discuss the difference between multi-morbidity and frailty. Multi-morbidity is considered the simultaneous presence of 2 or more chronic conditions in the same patient [36, 37]. Frailty and multi-morbidity are different syndromes although both entail elevated postsurgical risks [20]. One must understand that dealing with multi-morbidity in the frail geriatric surgical candidate requires medical optimization focusing on specific chronic medical conditions. The difficulty is that treating one disease may have ramifications ultimately not improving a patient’s overall health. An often cited example is improving the glucose control in a person with diabetes which may result in a fall secondary to hypoglycemia. Early postoperative feeding in a patient with undiagnosed gastroparesis can result in aspiration and its potential complications. When confronted with multiple clinical conditions, one should focus on the more clinically relevant conditions over less significant ones [38].

Frailty and Social Vulnerability

The deficit-driven definition of frailty also addresses social vulnerability. This definition looks beyond innate physiologic and biologic factors to include variables impacting from an “extrinsic social context.” The Social Vulnerability Index quantifies extrinsic factors such as socioeconomic status, living situation, and social engagement [39]. This index is related to a patient’s frailty. In other words it is part of how frail individuals are described through the accumulation of deficit model. Social vulnerability is higher in people who are frail. Social vulnerability is associated with higher mortality, independent of frailty. More work is needed to describe social vulnerability as it is now recognized that attention to social factors is essential to the care of the older patient [39].

Frailty and Reversible “Age Accelerating Causes”

While the biologic consequences of chronologic age can at times be influenced, it is often easier to target interventions on actual underlying diseases that are “age accelerating causes” of frailty. Malignancy, infections secondary to a chronic condition, and uncompensated single-end organ dysfunction are established causations leading to a frail state. An example is congestive heart failure secondary to aortic stenosis. Heart failure, a systemically impacting clinical condition, can lead to loss of skeletal muscle, immobility, and increased adipose tissue production to name a few. With continued heart failure exacerbations, frailty can easily develop or, if present, worsen [40]. Surgical intervention with an aortic valve replacement or left ventricular assist device, if successful, can reverse frailty developed secondary to the heart failure. This represents a disease-driven, end organ failure which differs from chronologic age-based frailty. Other examples of “accelerators” of clinical frailty that are reversible include HIV and end-stage renal disease.

Frailty Assessment in Surgical Practice

The utility of frailty in the spectrum of geriatric surgery is multifaceted. Overall the goals include maximizing quality of life while reducing comorbidity-associated disease burden, irreversible worsening of chronic disease, and “catastrophic” postsurgical events. Understanding frailty perioperatively allows evidence-supported risk assessments to assist in clinical decisions and allow for modification in the preoperative, intraoperative, and postoperative setting with the overall goal of improving surgical outcomes (Table 2).

Table 2 Examples of preoperative, intraoperative, and postoperative interventions
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Perioperative Interventions

Prehabilitation

Preoperative interventions aimed at improving a patient’s physiologic reserve to allow them to better tolerate surgical procedures has been shown to be successful. Carli et al. showed prehabilitation to enhance postoperative recovery of an octogenarian following robotic-assisted hysterectomy with endometrial cancer [41]. Prehabilitation has also been shown effective in colorectal, cardiac and abdominal surgery [42, 43].

Presurgical exercise programs in frail geriatric patients have shown shortened postoperative recovery, enhanced functional capacity, decreased mortality, and improved quality of life in cardiac and abdominal surgeries [43]. In elective cardiac surgery procedures, a Cochrane Review found that physical therapy reduced length of stay and decreased pulmonary complications [44]. In elective abdominal oncologic surgery, Dronkers et al. showed that preoperative therapeutic exercise was feasible and improved pulmonary function of patients when compared with home-based exercise instruction [45]. While the literature generally shows a very positive association with presurgical exercise interventions, more studies are needed to better understand the direct impact in the geriatric surgical population [46].

Preoperative multimodal approaches are also being trialed. Li et al. showed the positive impact tri-modal prehabilitation program (physical therapy, nutritional optimization, and anxiety reduction) has on functional recovery after colorectal cancer surgery [47].

More research is needed to better define what prehabilitation interventions are most appropriate. Further, practical questions that still remain include: 1. Who should be paying for it? 2. What setting is most appropriate (i.e., home versus care facility) and 3. Worth delaying something like an oncologic surgical resection for prehabilitation?

Delirium Prevention

Inouye et al. found that over a third of postoperative delirium is preventable [48]. Given the close link between postoperative delirium and frailty, it is crucial to address modifiable risk factors in the perioperative setting in order to minimize a patient’s risk of postoperative delirium. Evidence-based, postoperative delirium prevention protocols can be utilized in an anticipatory manner [49]. Also, when patients are flagged as having a higher chance of postoperative delirium, the anesthesiologist can consider alternatives such as regional block to possibly minimize postoperative narcotic analgesia or intraoperative EEG monitor to minimize depth of intraoperative sedation when possible [50, 51]. The Postoperative Delirium in Older Adults: Best Practice Statement from the American Geriatrics Society provides an excellent overview [52].

Palliative Care Discussion

While “palliative care” is often thought of as tantamount to withdrawal of care, its consideration is crucial when considering major surgical interventions in very frail patients. Incorporating principles of palliative care and having a palliative care discussion allows a patient to consider their personal goals, quality of life versus quantity of life in light of the procedure’s impact on quality of life, prognosis of recovery, and functional decline expectations [53, 54]. This conversation also allows a patient’s family to participate in discussing the pros and cons of undergoing a procedure and understanding realistic postoperative course expectations.

Intraoperative Setting Modifications

When a frailty assessment identifies a patient at increased surgical risk when undergoing certain procedures, less invasive procedures can be considered, different approaches can be discussed, or even medical management options can be considered.

Modification can include endoscopic versus open surgery or even pursuing medical management rather than surgical options. Endoscopic stenting of an obstructing pulmonary lesion may be considered over surgical resection. Biopsies could be performed under local rather than general anesthesia. A patient with acute appendicitis with high probability of poor operative outcomes could undergo medical management with antibiotics rather than surgical resection. While a diagnosis of frailty can prompt a surgeon to pursue less aggressive surgical options, research is still needed to evaluate the benefits of contouring surgical recommendations to frailty-based assessments. Further research is necessary to improve our understanding of outcome efficacy based on frailty assessments.

While best practice guidelines for an optimal anesthesia regimen have not been established, the literature supports minimizing general anesthesia sedation when possible. Further, utilization of regional and local anesthetics to allow for minimal sedation has shown great benefit particularly with regard to decrease in postoperative delirium. It has been most beneficial when an interdisciplinary approach between the surgeon and anesthesiologist discuss an operative plan and options [55].

Postoperative Expectations

Understanding frailty’s impact on a postsurgical course allows a surgeon to provide a more accurate depiction of expected surgical outcomes, possible complications, and recovery time. Knowing the reality of increased chance of certain complications or prolonged hospital admission can help a patient and their family have more realistic expectations of the postoperative recovery. It also enables them to plan expected stays at postacute care rehabilitation facilities or possibly arrange extra home care for a loved one. Also, acknowledging and addressing co-dependence and needs of a patient’s caregiver or family member before pursuing a major surgery with significant possible complications may relieve the patient and the caregiver/family’s apprehension and burden.

Conclusions

Discussions regarding surgical options, complications, and realistic postoperative outcomes can be taxing on both patient and their family. Shared decision-making models have helped patients understand their options and minimize decisional conflict [56]. Research is needed to understand the best use of shared decision making. Further, rather than focusing on procedural details, it is important for a surgeon to recognize and address what matters most to the patient and their family such as postoperative pain control, functional status, or being able to eat—quality versus quantity of life [57].

A multidisciplinary approach to the care of the geriatric surgical patient not only includes the longitudinal primary care provider, anesthesiologist, and surgeon, but also appropriate consultations from other health care professionals which may include oncology, cardiology, rehabilitation medicine, nutrition, and social work to help optimize the postsurgical outcomes of these challenging patients [55].