OBJECTIVES: Muscle loss during critical illness is well documented. The recovery of muscle loss in survivorship and its role in physical disability is not described. Our aims were to measure changes in dual x-ray absorptiometry (DXA) estimated lean and fat mass in Intensive Care Unit (ICU) survivors in the year following critical illness and compare to population controls. Secondary aims included examining the association between body composition and health-related quality of life (HrQOL).
METHODS: Using prospective observational data, we estimated spine and hip DXA derived lean and fat mass at discharge and 1-year follow up in adult ICU patients who underwent mechanical ventilation for at least 24 hours. Annualized total and percentage changes in lean and fat mass were compared to age-sex-height matched controls from the Geelong Osteoporosis Study (GOS) via multivariable linear regression analysis. HrQOL was measured via the EuroQOL-5D-3L and Pearson’s correlation coefficient used to determined its relationship with body composition.
RESULTS: Sixty-four cases were included, with median age 68.8yr [IQR60.8, 74.6], ICU length of stay 6.5d [IQR 4, 9] and duration of mechanical ventilation 87hrs [IQR 47, 143]. ICU survivors demonstrated greater annual increases in lean (+2.30%, 95%CI 1.64-2.95; p<0.001) and fat mass (+13.07%, 95%CI 9.37-16.78; p<0.001) than controls. At 1-yr follow-up lean mass values remained lower in the ICU group (-0.96kg, 95%CI -1.91 to -0.01; p=0.047). EuroQol measures at one-year were negatively correlated with fat (r=-.3) but not lean mass.
CONCLUSIONS: Mechanically ventilated adult ICU patients gained lean mass in the year following critical illness but did not reach the level of matched population-based controls. Fat mass was greater in ICU pts than controls and displayed negative correlation with HrQOL. Understanding the factors associated with, and effect of increasing muscle mass and reducing fat mass in the year after critical illness requires further investigation.