Skeletal Muscle Mass, Strength, and Functional Status in Critically Ill Older Adults Aged 60–75 and over 80 Years Old: An Exploratory Study

<b>Background:</b> 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. <b>Objective</b>: 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. <b>Methods:</b> 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. <b>Results:</b> 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): <i>p</i> < 0.001; rectus femoris (RF): <i>p</i> < 0.001; and total quadriceps (TQ): <i>p</i> < 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: <i>p</i> = 0.002; MRC-SS: <i>p</i> < 0.001; and FSS-ICU: <i>p</i> < 0.001). <b>Conclusions:</b> 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.