Association of baseline muscle mass with functional outcomes in intensive care unit survivors: A single-center retrospective cohort study in Korea

In critical care settings, ultrasound (US) of the quadriceps muscle and Bioelectrical Impedance Analysis (BIA) are noninvasive and widely available tools to evaluate muscle mass. We studied whether baseline muscle mass affects physical function in intensive care unit (ICU) survivors after discharge. This retrospective review of a prospective cohort enrolled 30 patients admitted to the medical ICU between April 2016 and June 2018. On ICU admission, quadriceps muscle thickness and skeletal muscle mass were measured using US and BIA, respectively. Muscle strength and physical function were measured using handgrip dynamometry, the 6-min walk test, and the Barthel index questionnaire survey during every clinic visit at 1, 3, 6, and 12 months after hospital discharge. Skeletal muscle mass at ICU admission was statistically correlated with the 6-min walk distance (6MWD) and Barthel index score. The segmental lean mass of the right arm was also positively correlated with handgrip muscle strength at 6 months after discharge. Likewise, the correlation between quadriceps muscle thickness at ICU admission and 6MWD at 6 months after discharge was positive and statistically significant. Multivariate regression analysis showed that skeletal muscle mass was associated with a reduced 6MWD, but the length of ICU stay was not. The segmental lean mass of the right arm also showed a significant association with handgrip strength after discharge. Low muscle mass on ICU admission is associated with reduced muscle strength, causing impaired physical function after hospital discharge in ICU survivors.