Muscular Echo-Intensity of the Quadriceps by Ultrasound Is More Related to Improvement of Gait Independence than Muscle Thickness in Older Inpatients.

OBJECTIVES: This study aimed to examine whether the decrease in muscular echo-intensity of the quadriceps by ultrasound in older inpatients is related to the improvement of gait independence than the increase of muscle thickness. DESIGN: Longitudinal study. SETTING: Hospital-based study. PARTICIPANTS: This study included 171 inpatients aged ≥ 65 years (median age: 84.0 [77.0-88.0], 56.1% female). Patients who were able to walk independently at hospital admission were excluded from the study. MEASUREMENTS: Improvement of gait independence during hospital stay was assessed using the change in Functional Independence Measure (FIM) gait score (i.e., FIM gait score at hospital discharge minus FIM gait score at hospital admission) and FIM gait score at hospital discharge. Muscular echo-intensity and muscle thickness of the quadriceps were assessed at hospital admission and discharge using ultrasound images, respectively. Muscular echo-intensity has been shown to be mainly related to intramuscular adipose tissue. Multiple linear regression analysis was performed to identify the factors independently associated with the change in FIM gait score and FIM gait score at discharge. RESULTS: Change in quadriceps echo-intensity was independently and significantly associated with the change in FIM gait score (ß = -0.22, p = 0.017) and FIM gait score at hospital discharge (ß = -0.21, p = 0.017). In contrast, change in quadriceps thickness was not independently and significantly associated with the change in FIM gait score (ß = 0.16, p = 0.050) and FIM gait score at hospital discharge (ß = 0.15, p = 0.050). CONCLUSIONS: Our study indicates that a decrease in muscular echo-intensity of the quadriceps by ultrasound is more related to the improvement of gait independence than an increase of muscle thickness in older inpatients. Intervention for intramuscular adipose tissue of the quadriceps may be important for improving gait independence in older inpatients.

Higher Body Mass Index in Hospitalized Older Patients Is Related to Higher Muscle Quality.

OBJECTIVES: This study aimed to examine the relationship between muscle mass, intramuscular adipose tissue, and body mass index (BMI) in older inpatients. DESIGN: Cross-sectional study. SETTING: Hospital-based study. PARTICIPANTS: This study included 413 inpatients aged ≥ 65 years (186 men and 227 women). MEASUREMENTS: Muscle mass and intramuscular adipose tissue of the quadriceps were assessed by measuring the muscle thickness and echo intensity on ultrasound images. To examine the relationship between quadriceps thickness and echo intensity and BMI in total participants and each sex, the Kendall rank correlation coefficient was used. Multiple regression analysis was performed to examine whether BMI was independently and significantly related to the quadriceps thickness and echo intensity, even after adjusting for other variables for total participants and each sex. The independent variables in multiple regression analyses were BMI, age, disease, days from onset disease. RESULTS: The results of the correlation analyses showed that BMI was significantly related to the quadriceps thickness (total participants, τ = 0.431; men, τ = 0.491; women, τ = 0.388) and echo intensity (total participants, τ = -0.239; men, τ = -0.318; women, τ = -0.188). In the multiple regression analysis, BMI was independently and significantly associated with the quadriceps thickness (total participants, ß = 0.535; men, ß = 0.548; women, ß = 0.519) and echo intensity (total participants, ß = -0.287; men, ß = -0.398; women, ß = -0.210). CONCLUSION: This study indicated that older inpatients with a higher BMI have greater muscle mass and less intramuscular adipose tissue of the quadriceps. These results suggested that a higher BMI in older inpatients is related to higher quadriceps muscle quality.