Skeletal Muscle Mass, Strength, and Functional Status in Critically Ill Older Adults Aged 60-75 and over 80 Years...

Background: Older adults are highly heterogeneous, spanning from robust to frail. Older adults aged ≥80 years (older 80+ group) admitted to an intensive care unit (ICU) present with greater severity and face higher risks of functional decline and mortality than younger ICU patients. Objective: This study compared the trajectory of skeletal muscle mass, strength, and functional status between ICU patients aged 60-75 years and those in the older 80+ group. Methods: A non-concurrent prospective observational study was conducted in older adults who were admitted to an ICU. Skeletal muscle mass, muscle strength and functional status from ICU admission to discharge were assessed. Results: Regarding muscle mass, no differences were observed at ICU admission in patients aged 60-75 years and those in the older 80+ group. However, both groups experienced a decrease in quadriceps muscle thickness (Time Effect: vastus intermedius (VI): p < 0.001; rectus femoris (RF): p < 0.001; and total quadriceps (TQ): p < 0.001) during their ICU stay. No differences were observed at awakening in handgrip strength (HS), Medical Research Council Sum Score (MRC-SS) and Functional Status Score for the Intensive Care Unit (FSS-ICU) between groups. However, HS, MRC-SS, and the FSS-ICU scale all increased from awakening to ICU discharge (Time Effect HS: p = 0.002; MRC-SS: p < 0.001; and FSS-ICU: p < 0.001). Conclusions: Both older adult groups admitted to the ICU experience a decline in skeletal muscle mass, muscle strength, and functional status during their ICU stay, with a tendency for the decline to be greater in the older 80+ group. In addition, critically ill older groups recover muscle strength and functional status from awakening to ICU discharge, with a tendency for the recovery to be smaller in the older 80+ group. These conclusions are based on trends observed in an exploratory study and require confirmation in larger trials.