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Objective:
Previous research has found that validated clinical questionnaires and functional evaluation for sarcopenia can be performed quickly and safely in the Radiology Department at the point of imaging care to supplement opportunistic CT [1]. This study examines the relationship of clinical, functional, and CT assessments of sarcopenia with all-cause mortality at 3 years in a cohort of older adult patients undergoing outpatient CT evaluation.

Materials and Methods:
The study included consecutive patients age >65 years undergoing routine outpatient abdominopelvic CT or PET/CT evaluation at a single tertiary care institution. At the time of the CT, patients completed validated screening questionnaires for sarcopenia (SARC-F) and frailty (FRAIL scale), and underwent measurement of grip strength (kg) and usual gait speed (6 m course) in the radiology department. Abnormal grip strength and gait speed are defined by the European Working Group on Sarcopenia in Older People (EWGSOP2, [2]). Skeletal muscle index (SMI, muscle area in cm2/patient height in m2) and skeletal muscle density (SMD) were measured on CT images at the T12 and L3 levels. Comparison of sex and other covariates and CT metrics were performed with t-tests. CT metrics were transformed into sex specific Z scores. For Cox proportional hazard analysis of CT metrics, patient groups were defined by those with Z < -1, and Z >= -1.

Results:
418 adults (201 men, 217 women; mean age 73.9 years [sd 6.2]; mean BMI 27.1 [sd 5.9]) were included. After a mean 3.10 ± 0.87 years of follow-up, 124 (29.7%) people died. Men and women did not differ in mean age, but BMI was higher in men (p < 0.0001). Men had higher SMI than women (p < 0.0001); SMD did not differ between men and women. Patient age, sex, BMI, and abnormal gait speed assessment were not associated with mortality risk. Abnormal grip strength (HR = 2.1, 95% CI [1.4-3.1]), SARC-F (HR = 1.6, 95% CI [1.1-2.4]), and FRAIL scale (HR = 2.2, 95% CI [1.5-3.1]) assessments were associated with diminished survival. Low T12-SMI (Z<-1) was associated with diminished survival (HR = 2.1, 95% CI [1.4-3.1)); Z < -1 for L3-SMI, L3-SMD, and T12-SMD were not predictive of survival. In a multivariable Cox analysis including abnormal grip, SARC-F, FRAIL scale assessments, and Z < -1 for T12-SMI, abnormal grip strength and FRAIL scale assessments, and low T12-SMI were significantly associated with reduced survival (HR = 1.55, 2.04, 1.72, 95% CI = [1.02-2.37], [1.32-3.15], [1.10-2.70], respectively), while abnormal SARC-F assessment was no longer significantly predictive.

Conclusion:
Common, standardized, clinical and functional screening assessments of sarcopenia obtained in the Radiology Department at the time of imaging can be predictive of all-cause mortality in an older adult, outpatient cohort. Of the common opportunistic CT metrics of sarcopenia we examined, low T12-SMI was significantly associated with higher mortality risk. Opportunistic CT may independently contribute to the prognostic value of clinical and functional assessments of sarcopenia.