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. Author manuscript; available in PMC: 2015 Nov 1.
Published in final edited form as: J Surg Res. 2014 Jun 11;192(1):19–26. doi: 10.1016/j.jss.2014.06.011

Analytic Morphomics Corresponds to Functional Status in Older Patients

Ashley L Miller ^, Lillian C Min ^,*, Kathleen M Diehl ^, David C Cron ^, Chiao-Li Chan ^, Kyle H Sheetz ^, Michael N Terjimanian ^, June A Sullivan ^, William C Palazzolo ^, Stewart C Wang ^, Karen E Hall ^,*, Michael J Englesbe ^
PMCID: PMC4188716  NIHMSID: NIHMS612932  PMID: 25015750

Abstract

Background

Older patients account for nearly half of U.S. surgical volume and age alone is insufficient to predict surgical fitness. Various metrics exist for risk stratification, but little work has been done to describe the association between measures. We aimed to determine whether analytic morphomics, a novel objective risk assessment tool, correlates with functional measures currently recommended in the preoperative evaluation of older patients.

Materials and Methods

We retrospectively identified 184 elective general surgery patients over age 70 with both a preoperative CT scan and Vulnerable Elderly Surgical Pathways and outcomes Assessment (VESPA) within 90 days of surgery. We used analytic morphomics to calculate trunk muscle size (total psoas area, or TPA) and univariate logistic regression to assess the relationship between TPA and domains of geriatric function – mobility, basic and instrumental activities of daily living (ADL), and cognitive ability.

Results

Greater TPA was inversely correlated with impaired mobility (OR=0.46, 95% C.I. 0.25–0.85, P=0.013). Greater TPA was associated with decreased odds of deficit in any basic ADLs (OR=0.36 per SD unit increase in TPA, 95% C.I. 0.15–0.87, P<0.03) and any instrumental ADLs (OR=0.53, 95% C.I. 0.34–0.81; P<0.005). Finally, patients with larger TPA were less likely to have cognitive difficulty assessed by Mini-Cog scale (OR=0.55, 95% C.I. 0.35–0.86, P<0.01). Controlling for age did not change results.

Conclusions

Older surgical candidates with greater trunk muscle size, or greater TPA, are less likely to have physical impairment, cognitive difficulty, or decreased ability to perform daily self-care. Further research linking these assessments to clinical outcomes is needed.

Keywords: Analytic morphomics, Trunk muscle size, Risk assessment Geriatric assessment, Activities of daily living, Mobility, Functional status

INTRODUCTION

Advances in surgical technology, increased life expectancy, and high demand have resulted in surgeons performing more operations on patients of advanced age.(1–3) Patients aged 65 years and older undergo surgical procedures at a rate two to three times that of the general population and account for almost 40% of operations performed in the United States.(1, 4) Given the heterogeneous presentation of these older patients,(5) it has become evident that age alone is insufficient to risk-stratify these patients for surgery.(6) Some variation in apparent physical fitness is appreciable by history and physical examination, but there exists a need for objective, time-efficient measures of physical fitness in the preoperative setting. Our recent work described the use of existing preoperative cross-sectional imaging to define surgical risk and has identified central sarcopenia as a strong marker of poor surgical outcomes in the general population.(7) In response, we have become interested in potential approaches to identify remediable surgical risk in older patients with the goal of optimizing high-risk patients for surgical procedures. The potential clinical application would be to optimize sarcopenic patients for surgery by prescribing physical exercise to increase muscle mass.

However, surgeons must appreciate a complex milieu of risk among older patients, especially those in the upper end of this age rage (i.e. age 70 and older). Older patients are more likely to have complex risk factors such as functional impairment and cognitive decline, which also impact surgical course.(5, 8–12) This marked variation in preoperative functional capacity has prompted a strong recommendation to employ geriatric assessment prior to surgery, for example in recent guidelines on the pre-operative care of the older surgical patient written by the American College of Surgeons.(5, 6, 13) The landscape of tests includes not only physical screens, such as ability to perform self-care(14, 15) and observed gait speed,(16) but also assessment of cognitive ability.(17, 18) Great enthusiasm has been shown for identifying various domains of risk, yet little work has been performed to describe the association between the various metrics in the older patient population.(19–21) We also do not fully understand how sarcopenia relates to the geriatric screening tests, and how they might overlap in these complex patients.(22, 23)

Therefore, we proposed this cross-sectional study of the relationship between central sarcopenia and risk factors identifiable by a comprehensive geriatric assessment in older patients planning to undergo elective general surgical procedures in the Vulnerable Elderly Surgical Pathways and outcomes Assessment (VESPA) study.(18) We aimed to determine the extent to which radiographic quantification of trunk muscle size is correlated with risk stratification measures currently used to assess fitness in older patients. We hypothesized that muscle size would be associated most closely with measures of physical function in older patients. However, because decline in cognition can precede or concur with diminished physical and functional capacity,(24, 25) we also anticipated correlation between trunk muscle size and self-care / cognitive measures.

METHODS

Study Design

We conducted an observational cross-sectional study of a subsample of patients in the VESPA study. The original VESPA study was a quality improvement intervention developed in 2008 as a collaborative effort between the Departments of Surgery and Medicine at the University of Michigan Health System (UMHS), an academic, tertiary referral center.(18) Briefly, the VESPA initiative implemented a brief geriatric assessment that could be administered by surgery physician assistants as part of preoperative evaluation for patients aged 70 and older with planned general surgery. In 2012, we formally evaluated the VESPA effort from 2008–11, obtained approval by appropriate institutional review boards at UMHS as human research, and described cross-sectional relationships between the risk factors.(18) Relevant to this study, the VESPA evaluation measured functional status (through performance of activities of daily living (ADLs), 6 basic ADLs and 8 instrumental ADLs, mobility (through a Timed Up and Go test (3-meter walk), gait evaluation (normal or unsteady), and any self-reported falls within the past year) and cognitive status (using a clock composition test and three item recall).(14–17)

Data

Among the 736 patients in the VESPA study, we retrospectively identified an analytic sample who also received a preoperative computed tomography (CT) scan of the thoracolumbar area within the UMHS health system within 90 days prior to their elective general surgery. The CT scan had to include the psoas muscle at L4. We did not exclude any CT scans based on clinical indication. No additional CT scans, other than those already clinically indicated and performed, were conducted for this study.

Measures (dependent variables)

The original VESPA study collected functional status as a series of self-reported questions regarding difficulty with ADLs. The questions modified the basic ADL and instrumental ADL items from the original severity scales(14, 15) to dichotomous responses, difficulty versus no difficulty, for each task. VESPA allowed for either self- or proxy-reporting. The surgery physician’s assistant performed both the interview and the physical examination to evaluate gait, balance, and cognition.

One challenge for the present analysis was to describe how TPA relates to the many VESPA items in broad domains. While some VESPA measures are physical (e.g., gait speed) and others are cognitive (e.g., the Mini-cog), ADLs require both cognitive and physical ability. Therefore we considered the individual VESPA items as three types: self-care (ADLs), mobility, and cognitive (Figure 1). Of the three domains, mobility measures depend more highly on physical reserve, and therefore we expected the mobility deficits to be strongly and inversely-correlated with TPA (i.e. increased muscle size would be associated with decreased difficulty in mobility).

FIGURE 1.

FIGURE 1

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Assessment measures and broad domains of geriatric function. Individual VESPA items were considered as one of three types: self-care (ADLs), mobility, and cognitive. Some measures included in the VESPA were purely physical (e.g., gait speed) or cognitive (e.g., the Mini-cog); however, ADLs require both cognitive and physical ability. Furthermore, among the ADLs, BADLs require more physical contribution than cognitive(28) while the opposite is likely for IADLs.(29–31)

For this study, we considered each of the ADL difficulties as a separate measure as well as part of one or more composite measures. The basic ADLs were bathing, dressing, transferring, feeding, grooming, and toileting; the instrumental ADLs were medication administration, meal preparation, telephone use, transportation, shopping, housekeeping, laundry, and finances. For composite measures, we considered a categorical variable indicating any basic ADL difficulty (versus no difficulty on any basic ADL) and another separate indicator for any instrumental ADL difficulty (versus no difficulty on any instrumental ADL). Last, we considered a final composite measure of any functional difficulty in either basic or instrumental ADLs versus no functional difficulty.

We categorized patients requiring greater than 20 seconds to walk 3 meters in the Timed Up and Go test(16) as having slow gait speed. We used the single-item physical evaluation of steady versus unsteady gait to classify patients with unsteady gait. Mobility deficit was defined as having either slow or unsteady gait. Fall history, while related to mobility, was a self-reported rather than performance measure, so was considered separately.

The Mini-Cog includes the clock composition test and three-item recall.(17) Although the Mini-cog uses a cut-off of 3 or less to classify as positive for impairment, there were only 3 patients below this cutoff (2.2%), thus we classified all patients with a score of 4 or less as having a cognitive deficit.

Morphomics (independent variable)

As a measure of trunk muscle size, we calculated the total psoas area (TPA) from preoperative CT scans. We have previously described methods used to measure TPA.(7, 26) Briefly, vertebral levels were identified on each patient’s CT scan to be used as anatomical landmarks. Using the transverse image at the L4 vertebral level, the left and right psoas muscles were outlined and the total area was calculated in centimeters. All image processing was performed using semi-automated algorithms programmed in MATLAB v13.0 (MathWorks, Natick, Mass). The population distribution of TPA in mm2 is depicted for males and females in Figure 2A and 2B, respectively. In order to analyze the TPA as a measure of sarcopenia in this study, we normalized the cross section by gender (because men have larger psoas muscles so naturally the cross-section is also larger for the same degree of sarcopenia). Therefore, we expressed our units of TPA in standard deviation units, for each patient’s psoas muscle size compared to the mean within their own gender (Figure 2C). This additional calculation also obviated the need to additionally control for gender.

FIGURE 2.

FIGURE 2

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TPA distribution of the study population. A. TPA distribution in mm2 for males (n=113). B. TPA distribution in mm2 for females (n=71). C. Population distribution of TPA, expressed in standard deviation units. Each patient’s psoas muscle size was compared to the mean within his or her own gender. A zero score indicates average.

Last, we also expressed TPA in tertiles in order to more easily display the results in terms of patients with small, medium, and large psoas muscle size.

Statistical Analysis

Descriptive statistics were calculated for the study cohort: continuous variables were described using mean and standard deviation, and categorical variables were summarized using proportions. To correlate TPA with individual VESPA components, we used univariate logistic regression. We determined the effect of each standard deviation increase in TPA on the likelihood of impairment in each dichotomous VESPA component. Next, we used univariate ordered logistic regression to assess the relationship between TPA and number of total deficits in basic and instrumental ADLs. We adjusted additionally for age in sensitivity analyses. A significance level of α=0.05 was used. All statistical analysis was performed using STATA v.12.

RESULTS

Patient Demographic and Clinical Characteristics

Of the 736 VESPA patients, 184 patients fulfilled study inclusion criteria (had an eligible preoperative CT scan). Patient demographic and clinical characteristics are detailed in Table 1A. The average age of our study cohort was 77.7 ± 5.4 years, and the majority of patients were male (61.4%). The average hospital stay for this cohort was 6.7 days. Gastrointestinal procedures comprised the largest fraction of the case mix (42%), followed by urologic (29%), and oncologic (13%) operations.

Table 1.

Patient characteristics (N=184)

A. Demographics Mean ± S.D. (or %)
Age (yr) 77.7 ± 5.4
Male 61.40%
Non-white race 8.70%
Height (in) 66.0 ± 3.6
Weight (lb) 175.0 ± 33.9
BMI (kg/m2) 28.3 ± 5.0
Total psoas area (mm2) 1904.7 ± 557.7
Length of stay (days) 6.7 ± 5.9
B. Preoperative VESPA Results N (%)
Mobility Timed ‘up and go’ test (N=139)
 <10 sec 66 (47.5)
 10–20 sec 54 (38.9)
 >20 sec 19 (13.7)
Unsteady gait (N=140) 27 (19.3)
Fall in past year (N=141) 32 (22.7)
ADL* Deficit in 1+ basic ADL (N=147) 6 (4.1)
 feeding 1 (0.7)
 transferring 5 (3.4)
 toileting 3 (2.0)
 dressing 3 (2.0)
 grooming 2 (1.4)
 bathing 4 (2.7)
Deficit in 1+ instrumental ADL (N=147) 32 (21.8)
 medication 5 (3.4)
 meals 13 (8.8)
 telephone 2 (1.4)
 driving 24 (16.3)
 grocery 16 (10.9)
 housekeeping 17 (11.6)
 laundry 19 (12.9)
 finances 11 (7.5)
Cognitive Mini Cog score (N=131)
 5/5 correct 102 (77.9)
 4/5 correct 26 (19.9)
 3/5 correct 1 (0.8)
 2/5 correct 1 (0.8)
 1/5 correct 1 (0.8)
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Preoperative Geriatric Screening Results

Preoperative VESPA results for the items used in our study are described in Table 1B. With regard to physical function, 62 out of 147 patients in our analytic sample (42.2%) were recorded as having a deficit in one or more items (fall, unsteady gait, or slow ‘up and go’ test). Few patients (n=6, 4.0%) reported difficulty with any basic ADL. One-fifth of our sample had an instrumental ADL difficulty on one or more tasks (n=32, 21.8%). Finally, 29 of 131 (22.1%) patients who participated in the Mini-cog exam scored 4 points or less.

Relationship between Total Psoas Area (TPA) and Individual Measures of Mobility

Figure 3 shows the relationship between increasing trunk muscle size (TPA) and the odds of impairment in mobility measures. Increasing TPA was inversely correlated with slow gait speed (OR=0.52 per SD unit increase in TPA, 95% C.I. 0.31–0.88, P=0.015). Patients with greater TPA were less likely to have unsteady gait (OR=0.39, 95% C.I. 0.23–0.65, P<0.001). The effect of TPA on both measures remains unchanged after adjusting for age. TPA was not related to positive screen for history of falling (OR=0.81, 95% C.I. 0.54–1.21, P=0.294). There was a significant effect of TPA as tertiles on gait speed and steadiness, but not on positive history of falls.

FIGURE 3.

FIGURE 3

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Relationship between mobility and trunk muscle size (TPA). The effect of a standard deviation unit increase in trunk muscle size on impairment in mobility measures is reported. Trunk muscle size was not correlated with positive screen for fall history. As trunk muscle size increased, patients were less likely to have unsteady gait (OR=0.39, 95% C.I. 0.23–0.65, P<0.001) or slow timed ‘up and go’ test results (OR=0.52, 95% C.I. 0.31–0.88, P=0.015).

Relationship between TPA and Individual Activities of Daily Living

Greater TPA (i.e., larger trunk muscle size) was associated with decreased incidence of any deficit in basic ADLs (OR=0.36 per SD unit increase in TPA, 95% C.I. 0.15–0.87, P=0.023). We did not find a significant relationship between TPA and odds of difficulty performing any individual basic ADL with the exception of transferring (OR=0.22, 95% C.I. 0.12–0.85; P=0.022; Figure 4A). Regarding overall number of basic ADL difficulties, increased TPA was associated with a decreased count of impairments in basic ADLs (OR=0.35 per additional difficulty, 95% C.I. 0.14–0.85; P=0.022).

FIGURE 4.

FIGURE 4

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Relationship between Activities of Daily Living (ADL) and TPA. A. Increases in TPA were associated with decreased incidence of any deficit in basic ADLs (OR=0.36 per SD unit increase in TPA, 95% C.I. 0.15–0.87, P=0.023). We did not find a significant relationship between TPA and any individual basic ADL item with the exception of transferring (OR=0.22, 95% C.I. 0.12–0.85; P=0.022). B. Patients with increased trunk muscle size were less likely to report difficulties performing any instrumental ADL (OR=0.53, 95% C.I. 0.34–0.81; P=0.004). We found a significant relationship between increased TPA and decreased odds of deficit in six of the eight individual instrumental ADLs (driving, finances, grocery shopping, housekeeping, laundry, and meal preparation). A significant relationship was not found between TPA and ability to administer medication or use a telephone.

There was an inverse relationship between increased TPA and reported difficulties performing any instrumental ADL (OR=0.53, 95% C.I. 0.34–0.81; P=0.004) (i.e. patients with larger TPA were less likely to report difficulties performing instrumental ADLs). We found a significant relationship between TPA and six of the eight individual instrumental ADLs (Figure 4B). Concerning overall burden of disability, increased TPA was associated with a decreased burden of impairments in instrumental ADLs (OR=0.48 per additional impairment, 95% C.I. 0.31–0.74; P=0.001).

There was a significant effect of TPA as tertiles on difficulty performing both basic and instrumental ADLs. Age did not significantly predict impairment in basic (P=0.689) or instrumental (P=0.085) ADLs. As a sensitivity analysis, age was added to each model with TPA, and no significant changes to the results were found.

Relationship between TPA and Cognitive Function

Patients with greater TPA were less likely to have a cognitive deficit as assessed by the Mini-Cog scale (4 of 5 or worse on Mini-Cog versus 5 of 5 points, OR=0.55 per SD unit increase in TPA, 95% C.I. 0.35–0.86, P=0.008) (Figure 5A). Age alone did not significantly predict the presence of cognitive deficit (P=0.074). The effect of the Mini-Cog remained significant after adjusting for age (OR=0.58, 95% C.I. 0.37–0.92, P=0.019). When TPA was stratified into tertiles, patients in the lowest tertile of TPA had odds of cognitive deficit that were three-fold higher than patients in the highest tertile of TPA (Figure 5B).

FIGURE 5.

FIGURE 5

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Relationship between cognitive function and TPA. A. Patients with larger trunk muscle size were less likely to have cognitive deficits as assessed by the Mini-Cog scale (OR=0.55 per SD unit increase in TPA, 95% C.I. 0.35–0.86, P=0.008). B. In order to further evaluate the association between trunk muscle size and preoperative cognitive abilities, we divided patients into tertiles based on their TPA size relative to other patients in our study cohort (highest, middle, lowest). Patients with the smallest core muscle area (lowest tertile) had a complication rate of 32% (15/47), which was higher than the group of patients in the middle tertile of core muscle size (24%, 9/37) and the patients in the highest tertile of core muscle size (11%, 5/47).

Relationship between TPA and Broader Functional Status Domains

Greater TPA was also inversely associated with deficits in the summary VESPA measures, summarized in Figure 6: any mobility impairment (OR = 0.41, 95% C.I. 0.25–0.67, P<0.001), any ADL impairment (OR=0.53 per SD unit increase in TPA, 95% C.I. 0.36–0.85), and any cognitive impairment (OR=0.55, 95% C.I. 0.35–0.86, P=0.008). As a final sensitivity analysis, all three composite measures were adjusted for age, which did not change the results.

FIGURE 6.

FIGURE 6

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Relationship between composite VESPA measures and TPA. We assessed the effect of a standard deviation unit increase in TPA on broad domains of geriatric function. Increased trunk muscle size was associated with decreased incidence of deficits in all three domains (mobility: OR=0.41, 95% C.I. 0.25–0.67, P=0.0001; ADLs (self-care): OR=0.53 per SD unit increase in TPA, 95% C.I. 0.36–0.85, P=0.004; cognitive: OR=0.55, 95% C.I. 0.35–0.85, P=0.008).

DISCUSSION

In this work, we describe the association of trunk muscle size, as measured by total psoas area, with three domains of ability (mobility, functional status, and cognition) in older elective surgical patients (Figure 6). Patients with larger TPA were less likely to have deficits in all three domains. Mobility and cognitive status were assessed through either direct observation (e.g. gait speed and cognitive testing) or through self-reported difficulty with basic and instrumental ADLs(24), whereas TPA was measured quantitatively by calculation of psoas area on preexisting computerized tomography images obtained previously during clinical care.

These results have implications relevant to both clinical care of geriatric surgery patients and future research in surgical risk prediction. TPA, a novel radiologic measure of sarcopenia, has been shown to identify risk for post-operative complications among younger patients.(27) We anticipate future testing of how TPA might predict risk in older patient populations. However, prior to this future research, it is important to understand what TPA means in context of the geriatric patient, through cross-sectional analysis with other measures of preoperative ability. To better under the relationships between TPA and the many VESPA measures, we used underlying geriatric principles to group the measures into three broader domains (Figure 1). While some measures were purely physical (e.g., gait speed) or cognitive (e.g., the Mini-cog), ADLs require both cognitive and physical ability. Furthermore, among the ADLs, BADLs require more physical contribution than cognitive,(28) while the opposite is likely for IADLs.(29–31) Contrary to our expectations, we found a more robust association between TPA with the cognitive testing and cognitively intense instrumental ADLs than the physical measures (mobility and BADLs). Frailty, or its various components including grip strength and gait speed, have been found to be correlated with cognitive impairment, possibly due to shared causes such as inflammation and cardiovascular risk(32) We posit that TPA is associated with frailty, therefore explaining the association we found in our sample. Due to the cross-sectional study design, the association should not be interpreted as causal.

The multi-dimensional relationship of TPA with function poses important implications for future interventions. Measuring TPA has been proposed as a way to identify patients who would most benefit from preoperative optimization of physical health, for example through more intensive “prehabilitation” prior to surgery. These results suggest that efforts to optimize older sarcopenic patients for elective surgery may be more complicated than for younger patients. Purely physical interventions recommended to younger elective surgery patients (which focus solely on increasing muscle strength and endurance) may need to be adapted to older patients, especially those with cognitive difficulty. This might include tailoring the “one size fits all” approach in current research to less-intense regimens and providing patient educational materials to accommodate patients with cognitive, sensory or physical impairments, or those who have caregivers as coaches.

Assessments such as those employed by the VESPA study have become mainstream, recommended surgical care processes in the evaluation for older patients.(13) Though formal research on geriatric risk indices in surgery is still in its infancy, there is evidence of their association with in-hospital occurrences, total length of stay, post-discharge institutionalization, and mortality.(9, 33–36) One concern is that comprehensive geriatric assessment (e.g., performing all domains of assessment) is not feasible in a busy surgical preoperative practice and the assessments are likely performed with less reliability in this setting compared to prior formal research studies.(6, 33, 37, 38) TPA is also correlated with postoperative outcomes, including length of stay, payer costs, surgical complication rate, and mortality.(7, 26, 27, 39) As a quantitative measure, TPA would be a more precise index than the geriatric assessments. Because TPA is computerized, it could also be more objective than geriatric assessment. Once incorporated into a sophisticated medical record system, analytic morphomics technology would not require any new imaging nor additional valuable face-to-face clinical time, potentially resulting in an efficient new risk-prediction tool in older patients. More work is needed to develop clinically relevant protocols using analytic morphomics for real-time assessment of surgical fitness, and to determine how well it performs in comparison to traditional preoperative cardiac evaluation and the geriatric assessments.(7, 26)

This study has several important limitations. First, it was conducted at a single academic, tertiary-referral center, which potentially may limit the results to patients of similar centers. To improve generalizability, future studies should include patients receiving surgery at community centers, and centers across US regions with differing utilization of elective surgery. Second, the majority of patients in this study were male. Given the significant difference in muscle mass between males and females, future prospective trials should enroll both genders in equal numbers. Third, only patients with a preoperative CT of the thoracolumbar area and a planned surgical procedure were included in this study. Patients requiring thoracolumbar CT scans (e.g., to evaluate malignancies) are more likely to have organ-based disease, and these patients are therefore likely to be sicker than those not requiring CT scans. Also, we expect that patients who receive preoperative evaluation would naturally differ from patients who prefer no surgery, who would not be in this study. Therefore, our results only generalize to those patients with similar need for preoperative imaging and desire for preoperative evaluation. Fourth, we tested many risk factors across several domains of function in older surgical patients. It is possible that testing many risk factors results in a few positive findings due to chance. However, we observed consistent relationships across broad categories of risk factors, making this error less likely. One potential direction would be to test the composite domains (cognition, self-care, or mobility) as the primary research question in further research. Fourth, we had too few patients with abnormal Mini-Cog Assessment to use the traditional cutoff of 3 or fewer points, and therefore had ceiling effects. Other groups have also increased the conventional dementia-screening threshold of the Mini-Cog in order to maximize sensitivity(40) and capture patients with more mild cognitive impairment. In this population, future work should utilize more robust cognitive assessments to increase sensitivity for mild cognitive impairment. One direction would be to add more sensitive tests of multi-tasking (e.g., alternating Trails B test to better test concentration, executive function, and mental processing(41)) that could be more clinically relevant than the Mini-cog for patients seeking to return home with complex post-operative instructions after surgery. Similarly, we were able to detect an association between basic ADLs and TPA, but not between TPA and individual items due to the small numbers of patients within each ADL. The association was not detectable until we used the composite measure. Future studies should enroll a larger patient sample, which would also permit testing of confounding variables beyond age. Last, we used a novel radiologic definition (loss of muscle mass) to classify sarcopenic patients. The consensus diagnostic definition of sarcopenia is relatively new and work to delineate a universal operational definition of sarcopenia that is clinically relevant to surgeons remains ongoing.(42–44)

Designing clinically relevant preoperative training programs in older patients requires an enhanced understanding of the relationship between low muscle mass and other determinants of preoperative risk, which include both physical and cognitive abilities. We found that our morphometric measure, TPA, had broad associations across functional domains in older patients. In patients with preoperative imaging, morphomic measures may be an efficient and complementary preoperative assessment. Further work is needed to elucidate how morphometric measures, age, and functional impairment predict clinical outcomes in older patients as well as its utility in selecting patients for targeted prehabilitation programs.

Footnotes

All 12 authors included on this manuscript participated in study design, development of methodology, data collection, and analysis of the VESPA and/or analytic morphomics studies as well as the design, data analysis, and creation of the manuscript for this study. Work was done within a student career development program. All students added substantial value, and with mentorship, this significantly added to the number of authors.

Financial Disclosure: Older Americans Independence Center at University of Michigan (AG024824 Diehl & Min), Medical Student Aging Research Program (Miller). MJE was supported by NIH – NIDDK (K08 DK0827508).

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