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Observational Study
. 2014 Nov;192(1):19-26.
doi: 10.1016/j.jss.2014.06.011. Epub 2014 Jun 11.

Analytic Morphomics Corresponds to Functional Status in Older Patients

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Free PMC article
Observational Study

Analytic Morphomics Corresponds to Functional Status in Older Patients

Ashley L Miller et al. J Surg Res. .
Free PMC article

Abstract

Background: Older patients account for nearly half of the United States 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 aged >70 y with both a preoperative computed tomography scan and Vulnerable Elderly Surgical Pathways and outcomes Assessment within 90 d of surgery. We used analytic morphomics to calculate trunk muscle size (or total psoas area [TPA]) and univariate logistic regression to assess the relationship between TPA and domains of geriatric function mobility, basic and instrumental activities of daily living (ADLs), and cognitive ability.

Results: Greater TPA was inversely correlated with impaired mobility (odds ratio [OR] = 0.46, 95% confidence interval [CI] 0.25-0.85, P = 0.013). Greater TPA was associated with decreased odds of deficit in any basic ADLs (OR = 0.36 per standard deviation unit increase in TPA, 95% CI 0.15-0.87, P <0.03) and any instrumental ADLs (OR = 0.53, 95% CI 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% CI 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: Activities of daily living; Analytic morphomics; Functional status; Geriatric assessment; Mobility; Risk assessment; Trunk muscle size.

Figures

FIGURE 1
FIGURE 1
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.(–31)
FIGURE 2
FIGURE 2
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.
FIGURE 3
FIGURE 3
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).
FIGURE 4
FIGURE 4
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.
FIGURE 5
FIGURE 5
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).
FIGURE 6
FIGURE 6
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).

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