Preoperative Evaluation of the Frail Patient

Lolita S. Nidadavolu, MD, PhD; April L. Ehrlich, MD; Frederick E. Sieber, MD; Esther S. Oh, MD, PhD


Anesth Analg. 2020;130(6):1493-1503. 

In This Article


Frailty Assessment Tools

Conceptual Frameworks Behind Frailty Assessment Tools. There are 2 major conceptual frameworks behind the most commonly used frailty measurement tools.[10] The first is the concept of frailty as a biological syndrome characterized by energy depletion as exemplified by the PFP (Table 1). The PFP takes into account physical measurements of grip strength and walking speed and raises questions about exhaustion, physical activity, and unintentional weight loss as key clinical presentations of decreased physiologic reserve.[3] The 5 components of the PFP are considered to be proxy measurements of dysregulation in stress response and energy metabolism.[10]

The second framework for defining frailty is considering frailty as an accumulation of deficits across functional, physical, cognitive, and social measures.[10] Instruments that define frailty as "deficit accumulation" include the DAI, the Johns Hopkins Adjusted Clinical Groups (JHACG) frailty assessment, and the modified Frailty Index 11 (mFI 11).[9,21,22] These tools measure factors including nutrition, comorbidities, functional status, disability, and mental health, and a cumulative score is derived. Similarly, the Brief Frailty Instrument by Rockwood[15] incorporates an operational definition of frailty beyond measuring activities of daily living by including cognitive impairment and incontinence components to their tool. The JHACG frailty assessment and DAI utilize specific diagnosis codes or the presence/absence of specific comorbidities to define a frail subset of patients (Table 1).[9,21] Both the PFP and deficit accumulation models, such as the DAI and mFI 11, are more predictive of a patient's cumulative risk of adverse outcomes than age alone.[10]

Measurement Issues in Frailty Assessment Tools. Although there is a range of factors that comprise different frailty assessment tools, 2 domains (ie, physical and cognitive function) that may require active measurement are discussed below.

Physical Measures: The 2 physical measurements in the PFP—gait speed and handgrip strength—require training to standardize measurements. A comprehensive review of handgrip strength measurement demonstrates that factors—model of dynamometer, posture and arm position of patient, and handle position—can influence results and make it challenging to compare results when different protocols are used.[25] Gait speed measurement and Timed Up and Go (TUG) testing requires a dedicated location where 4- and 3-m markings can be placed on the floor for the respective tests.[24,26] This requirement for specialized equipment and space may be challenging for some outpatient preoperative clinics or in the home of a patient. In addition, patients with limited mobility due to pain may find their preoperative gait speed and TUG measurements to be an inaccurate assessment of their premorbid functioning.

Cognitive Assessments: Underlying cognitive impairment is a well-known risk factor for many different postoperative complications including delirium. In 1 recent study of over 7800 patients undergoing hip fracture repair, dementia diagnosis was one of the strongest risk factors for postoperative delirium.[27] Patients identified as having mild cognitive impairment (MCI) before surgery were also at higher risk of developing postoperative delirium, and demonstrated increased risk of adverse outcomes, specifically higher rates of discharge to a postacute facility and new impairment in cognitive instrumental activities of daily living (IADL) 1 month later.[28] A study of cognitively impaired patients undergoing vascular surgery demonstrated significantly higher rates of wound infections and longer LOS (>10 days) compared to cognitively normal patients.[29] Furthermore, patients with dementia are at higher risk of mortality after surgery compared to patients with normal cognition (hazard ratio [HR] = 1.84; 95% confidence interval [CI], 1.10–3.07).[30]

Despite the strong association of underlying cognitive function with poor postoperative outcomes, not all frailty assessment tools incorporate cognitive assessment. The PFP; Vulnerable Elders Survey (VES); Fatigue, Resistance, Ambulation, Illnesses, Weight Loss (FRAIL) Scale; and mFI 11 do not have an explicit component of preoperative cognitive assessment built into their assessment tools. The DAI and JHACG rely on self-report of cognitive impairment, and the Edmonton Frail Scale (EFS) has a limited active cognitive screening component (eg, clock draw). Active measurement of cognitive function is important as these measures may be used to determine a patient's response to perioperative stressors and could allow monitoring of longitudinal cognitive trajectory.[31]

With respect to the feasibility of incorporating cognitive assessment into an outpatient preoperative visit, the Montreal Cognitive Assessment (MoCA)—a well-validated study with high reliability—can be completed in approximately 10 minutes.[29] A review by Long et al[32] details several other short (≤2.5 minutes) cognitive assessments that can be completed preoperatively including the Mini-Cog, which consists of a 3-word recall and clock drawing test. Incorporating cognitive testing in a preoperative clinic has been shown to be feasible and not burdensome to either practitioners or patients.[33] Due to the lack of active cognitive screening component in most frailty assessment tools, it would be important to incorporate an additional cognitive screening measure into the perioperative workflow.

Time to Complete Frailty Assessments. One of the challenges of preoperative evaluation for frailty is the length of time to perform such assessments in a busy outpatient clinic.[10] In general, newer frailty assessment tools are designed to be shorter in duration and more conveniently performed in an outpatient preoperative clinic (Table 1). At this time, tools such as the PFP require patient participation, specialized equipment, staff training for standardized assessment, and additional time to perform the physical measurements. Simpler versions of existing frailty tools continue to be developed (eg, the modified Frailty Index 5 [mFI 5]). MFI 5 uses a subset of measures from the mFI 11 and has also been shown to have good sensitivity for identifying frail older adults preoperatively.[22,34] Frailty assessment tools, such as mFI 11 and JHACG, are further streamlined by relying on data from electronic medical records or the American College of Surgeons National Surgical Quality Improvement Program (ACS-NSQIP) database. Relevant medical comorbidities, changes in weight, and baseline physical and cognitive function can be identified and used in these frailty assessment tools without relying solely on patient self-report.

Postoperative Outcomes Associated With Frailty

Frail patients overall have worse health care outcomes (eg, postoperative complications, LOS, mortality) compared to nonfrail counterparts in both elective and emergent surgical procedures (Table 2). Frail and nonfrail patients had similar surgical procedures in these studies, with exception of vascular procedures, in which frail patients primarily underwent peripheral vascular interventions and were less likely to have major elective vascular surgery than nonfrail patients.[47] A study examining general, vascular, cardiac, thoracic, and orthopedic surgeries in a large population showed that the most robust patients (Risk Analysis Index [RAI] ≤ 10) comprised 80% of the surgical population, while frail patients (RAI ≥ 21) comprised only 7% of the population.[11] As frail patients constitute approximately 15% of community-based individuals who are over 65 years of age,[62] there may be a selection bias where poor operative candidates are excluded from undergoing surgery.[63] This discordance between the percentage of frail patients in the overall population compared to the percentage of frail patients undergoing major surgical procedures suggests that surgical studies are likely to underestimate postoperative risk in frail patients.

Postoperative Complications. Overall, higher post operative complication rates were associated with frailty status (Table 2). A study examining emergency general surgeries by Joseph et al[36] showed that major complication (eg, sepsis, pneumonia, deep venous thrombosis) rates in frail patients were >3 times more likely than in robust patients (odds ratio [OR] = 3.87; 95% CI, 1.69–8.84). All 4 studies examining patients undergoing orthopedic surgeries (elective and hip fracture repairs) demonstrated higher rates of complications for patients categorized as frail as well.[5,46,49,55] Although many of the studies did not examine delirium as one of the main postoperative complications, 1 study by Gleason et al[49] demonstrated that postoperative delirium rates were higher in frail compared to nonfrail patients undergoing orthopedic procedures (28% vs 3.4%, P = .01).

In terms of frailty tool–specific findings, frailty status as defined by the DAI, Groningen Frailty Indicator (GFI), VES, and Clinical Frailty Scale (CFS) was associated with higher rates of postoperative complications in patients undergoing emergency surgery;[35,36,43,44] however, this was not observed with the Brief Frailty Instrument.[35] Interestingly, the VES and GFI were used alongside the Brief Frailty Instrument in the same surgical population to categorize frailty status. Frailty identified by VES and GFI was associated with higher rates of complications in frail patients suggesting that the Brief Frailty Instrument may underestimate risk of postoperative complication in this population.[35] A meta-analysis examining mFI 11 use across various surgical settings showed higher risk of all complications (relative risk [RR] = 1.48; 95% CI, 1.35–1.61), Clavien-Dindo Class IV complications (requiring critical care management) (RR = 2.03; 95% CI, 1.26–3.29), and wound complications (RR = 1.52; 95% CI, 1.47–1.57) for frail patients compared to robust patients.[54]

A large retrospective study by Shah et al[54] using data from ACS-NSQIP demonstrated that frailty is associated with higher complication rates even in low-risk procedures (average 30-day mortality rate ≤1%). In this study, the proportion of individuals with any complication was higher in the most frail group (Clinical Risk Analysis Index [RAI-C] >40) compared to the robust group (RAI-C ≤10) undergoing low-risk procedures (42.9% vs 4.4%, P < .001). Findings were similar for major complications in the same population and with higher proportion of individuals with major complication in the most frail group (RAI-C >40) compared to the robust group (RAI-C ≤10) (36.4% vs 3.2%, P < .001). Both of these findings suggest a dose–response association between the degree of frailty and the number of postoperative complications.[11]

Length of Stay. Frailty was significantly associated with LOS in 20 of 22 studies (Table 2). Two studies that did not show significant association of frailty with LOS examined elective general surgery and vascular procedures and, in general, had smaller samples compared to the studies that showed significant associations.[12,38] One study using 2 different frailty assessment tools in elective total joint replacement patients showed that the frailty status categorized by the CFS was significantly associated with LOS while those categorized by FRAIL scale was not.[42] The CFS is based on the deficit accumulation model,[18] and the FRAIL scale is based more on Fried's phenotypic model.[20,42] The authors postulated that their study population, which consisted of elective orthopedic surgery patients, may have excluded more frail patients (eg, the hip fracture population).[42]

Factors that could be contributing to increased LOS for frail patients are increased postoperative complication rate and additional time required to arrange discharge to skilled facility. Among the orthopedic surgeries that examined LOS as an outcome, 7 of 8 studies demonstrated significantly increased LOS in frail patients. Frailty assessment tools used in these studies ranged from DAI, PFP, CFS, FRAIL scale, and mFI. In general, most studies examined LOS as a continuous variable. Gleason et al[49] examined LOS as both a binary (> or ≤6 days) and a continuous variable and found statistically significant associations of higher frailty score with longer LOS in both analyses.

The study by Drudi et al[38] demonstrated association of frailty with mortality and worsening disability after interventions for peripheral arterial disease (PAD) but not with LOS. The study by Vernon et al[12] using the VES in patients undergoing elective surgical procedures examined LOS as a binary variable to primarily observe whether patients required noninvasive positive pressure ventilation following their procedure or an unanticipated hospital stay. However, the authors state that their study was significantly limited by missing data, with only 48 of 103 patients having complete surveys from which the researchers could calculate frailty score. Smaller sample size may have contributed to the nonsignificant findings between frailty status and LOS in this study.[12]

Postoperative Mortality. Twenty-five studies specifically examined associations between frailty status and 30-day mortality. One study by McIsaac et al[50] examining independent, community-dwelling patients demonstrated that mortality was particularly high among frail patients in the immediate postoperative period. In this study, frail patients undergoing emergency surgical procedures were 23 times as likely as nonfrail patients to die on postoperative day 1 (HR = 23.1; 95% CI, 22.3–24.1).[50] Among patients undergoing major elective noncardiac surgery, 1-year mortality remained increased for frail versus nonfrail patients even after adjusting for demographics, procedure types, and 19 different medical comorbidities (HR = 1.36, 95% CI, 1.26–1.46).[51] Other studies of patients undergoing emergency procedures demonstrated similar increases in rates of postoperative mortality for frail patients.[35,36,43,44] Four of the 25 studies did not show statistically significant associations between frailty and postoperative mortality.[37,38,46,49] These studies had smaller sample sizes and included patients undergoing hip fracture repair, general orthopedic surgeries, and vascular surgery.[38,46] One study by Hall et al[23] examining elective surgery patients showed, for those determined to be frail, that mortality 1 year following surgery remained elevated compared to the overall 1-year mortality for the group (26.8% vs 3.5%).

Postoperative Discharge Disposition and 30-day Readmission Rates. A majority of the results from Table 2 demonstrate that, depending on the type of surgery, frail patients are at higher risk of functional impairment from prolonged LOS or complications than a nonfrail patient. These adverse outcomes can lead to patients requiring discharge to subacute nursing facilities for continued care. One study found that frail vascular surgery patients were 1.6 times as likely as robust patients to be discharged to a postacute care facility instead of their homes (OR = 1.6; 95% CI, 1.4–1.8).[56] Orthopedic surgery studies examining discharge disposition demonstrated that the PFP, DAI, CFS, and mFI,[5,42,55] but not the FRAIL scale, were associated with increased rates of discharge to skilled facilities in this population.[42] Among community-dwelling older adults undergoing emergency surgery, frail patients were 5.8 times as likely as robust patients to be discharged to a postacute care facility (OR = 5.8; 95% CI, 5.53–6.12).[50] A meta-analysis looking at the use of mFI 11 in surgical patients similarly showed increased relative risk of discharge to postacute care following surgery for frail patients compared to robust patients.[54] The frailty assessment tools that demonstrate positive associations between frailty and 30-day readmission are the mFI and RAI-C, examining general surgery, total hip arthroplasty, and general urological procedures[54,55,60] (Table 2).

Comparison of Frailty Tools to Other Surgical Risk-stratifying Tools. Frailty assessment tools have been compared to other tools assessing surgical risk (eg, ASA classification and comorbidity index). One study looking at mFI 11 in total hip arthroplasty population showed that mFI 11 was a stronger predictor of readmission rates (OR = 14.72; 95% CI, 6.95–31.18) than the ASA classification or age.[55] MFI 11 was also a better predictor of any complication (OR = 3.63; 95% CI, 1.64–8.05) and reoperation (OR = 6.52; 95% CI, 2.48–17.13), while ASA classification and age did not show statistically significant association with these outcomes.[55] Other studies showed that frailty was predictive of higher risk for 30-day mortality and discharge to a skilled facility, while age and ASA score were not associated with these outcomes.[36,47] However, 1 study found that addition of frailty measurement to ASA class improved the ability to predict postoperative complications and discharge to a skilled nursing facility.[39]