Intramuscular adipose tissue in the quadriceps is more strongly related to recovery of activities of daily living than muscle mass in older inpatients

Abstract

Background The relationship between intramuscular adipose tissue at admission and recovery of activities of daily living (ADL) remains unclear. This study aimed to examine the relationship between intramuscular adipose tissue in the quadriceps at admission and recovery of ADL in older inpatients. Methods This prospective study included 404 inpatients aged ≥65 years (54.7% female). Recovery of ADL during hospital stay was assessed using the Barthel Index (BI) score at discharge, BI score change, and BI efficiency. Higher BI at discharge, BI score change, and BI efficiency indicate more improvement in ADL. Intramuscular adipose tissue and muscle mass of the quadriceps were assessed using echo intensity and muscle thickness on ultrasound images, respectively. Multiple regression analysis was performed to identify factors independently associated with BI score at discharge, BI score change, and BI efficiency. The independent variables were BI score at admission, echo intensity and muscle thickness of the quadriceps, age, sex, number of medications, C‐reactive protein concentration, updated Charlson Comorbidity Index score, Food Intake Level Scale, Geriatric Nutritional Risk Index score, days from onset disease, length of hospital stay, number of units of rehabilitation therapy, and subcutaneous fat thickness of the thigh. Results The medians (inter‐quartile range) of the BI score at discharge, BI score change, and BI efficiency were 60.0 (35.0–80.0), 10.0 (0.0–25.0), and 0.11 (0.00–0.37), respectively. The median (inter‐quartile range) of the length of hospital stay (days) and days from onset disease were 58.0 (39.0–92.0) and 79.0 (49.0–112.0), respectively. Quadriceps echo intensity was independently and significantly associated with the BI score at discharge (β = −0.13, P < 0.01), BI score change (β = −0.23, P < 0.01), and BI efficiency (β = −0.21, P < 0.01). Quadriceps thickness was not independently and significantly associated with the BI score at discharge (β = −0.02, P = 0.68), BI score change (β = −0.02, P = 0.79), and BI efficiency (β = 0.03, P = 0.67). Conclusions Our study indicates that greater intramuscular adipose tissue in the quadriceps at admission is more strongly related to worse recovery of ADL than less muscle mass in older inpatients. Greater intramuscular adipose tissue in the quadriceps in older inpatients is considered to be a predictor of worse recovery of ADL, and intervening for greater intramuscular adipose tissue may be important for improving ADL in older inpatients.

Associations of ADL Disability With Trunk Muscle Mass and Muscle Quality Indicators Measured by Opportunistic Chest Computed Tomography Imaging Among Older Inpatients

“…Based on a cross-sectional study with 371 older inpatients, Akazawa et al (11) reported that increased IntraMAT of the quadriceps was more strongly associated with declines in ADL than the loss of muscle mass. Most recently, the same team conducted a prospective cohort study with 404 older inpatients, and they found that increased IntraMAT of the quadriceps at admission was more strongly associated with worse recovery of ADL than the loss of muscle mass (10). Notably, both studies used ultrasound to measure muscle thickness and measured echo intensity as the surrogates of muscle mass and IntraMAT, respectively.…”

Relationship between muscle mass and fraction of intramuscular adipose tissue of the quadriceps in older inpatients

“…On the other hand, the European Working Group of Sarcopenia in Older People2 (EWGSOP2) [ 4 ] suggested the importance of assessing not only muscle mass but also muscle quality, which includes the infiltration of fat into muscle, ratio of muscle strength to appendicular skeletal muscle mass, and bioimpedance analysis-derived phase angle, in the diagnosis of sarcopenia. Among the muscle quality parameters, intramuscular adipose tissue has been shown to be more closely related to muscle strength [ 5 , 6 ], stand-up, sit-down [ 5 , 7 ], and gait abilities [ 6 , 8 , 9 ], activities of daily living [ 10 , 11 ], swallowing function [ 12 , 13 ], onset of hip fracture [ 14 ], and mortality [ 15 ] than to muscle mass. Fraction of intramuscular adipose tissue is assessed with the echo intensity of the ultrasound image [ 5 – 13 ].…”

Image_1.pdf

“…Only two previous studies addressed the associations of muscle mass and muscle quality with ADL in older inpatients (10,11). Based on a cross-sectional study with 371 older inpatients, Akazawa et al (11) reported that increased IntraMAT of the quadriceps was more strongly associated with declines in ADL than the loss of muscle mass.…”