Can Sarcopenia Quantified by Ultrasound of the Rectus Femoris Muscle Predict Adverse Outcome of Surgical Intensive Care Unit Patients as well as Frailty? A Prospective, Observational Cohort Study

Abstract

Objective: To compare sarcopenia and frailty for outcome prediction in surgical intensive care unit (SICU) patients.

Background: Frailty has been associated with adverse outcomes and describes a status of muscle weakness and decreased physiological reserve leading to increased vulnerability to stressors. However, frailty assessment depends on patient cooperation. Sarcopenia can be quantified by ultrasound and the predictive value of sarcopenia at SICU admission for adverse outcome has not been defined.

Methods: We conducted a prospective, observational study of SICU patients. Sarcopenia was diagnosed by ultrasound measurement of rectus femoris cross-sectional area. Frailty was diagnosed by the Frailty Index Questionnaire based on 50 variables. Relationship between variables and outcomes was assessed by multivariable regression analysis NCT02270502.

Results: Sarcopenia and frailty were quantified in 102 patients and observed in 43.1% and 38.2%, respectively. Sarcopenia predicted adverse discharge disposition (discharge to nursing facility or in-hospital mortality, odds ratio 7.49; 95% confidence interval 1.47-38.24; P = 0.015) independent of important clinical covariates, as did frailty (odds ratio 8.01; 95% confidence interval 1.82-35.27; P = 0.006); predictive ability did not differ between sarcopenia and frailty prediction model, reflected by χ values of 21.74 versus 23.44, respectively, and a net reclassification improvement (NRI) of -0.02 (P = 0.87). Sarcopenia and frailty predicted hospital length of stay and the frailty model had a moderately better predictive accuracy for this outcome.

Conclusions: Bedside diagnosis of sarcopenia by ultrasound predicts adverse discharge disposition in SICU patients equally well as frailty. Sarcopenia assessed by ultrasound may be utilized as rapid beside modality for risk stratification of critically ill patients.

Conflict of interest statement

The authors declare no conflicts of interest to disclose.

Figures

FIGURE 1

Patients’ flow through the study. *Manual muscle testing could not be completed during SICU stay in 6 patients due to delirium (n = 3), patient refusal (n = 1), transfer (n = 1), and mortality (n = 1).

FIGURE 2

Representative transverse ultrasound image of the rectus femoris muscle acquired with a 3 to 12 MHz linear transducer (Philips Medical Systems, Bothell, WA) using musculoskeletal settings. F, femur; VI, vastus intermedius; VL, vastus lateralis; VM, vastus medialis.

FIGURE 3

Frailty and sarcopenia are associated variables that equally well predict adverse discharge disposition. A, Relationship between sarcopenia and adverse discharge disposition defined as discharge to skilled-nursing facility or in-hospital mortality. B, Relationship between frailty and adverse discharge disposition. C, Scatterplot of frailty index versus cross-sectional area of rectus femoris muscle as measured by ultrasound. A significant correlation was found between the frailty index and sex-adjusted cross-sectional area of rectus femoris muscle (Spearman r = −0.52, P < 0.001).