Functional ability and quality of life in critical illness survivors with intensive care unit acquired weakness: A secondary analysis of a randomised controlled trial

Introduction: Intensive care unit acquired weakness (ICUAW) may contribute to functional disability in ICU survivors, yet performance-based data for general ICU patients are lacking. This study explored functional outcomes of (1) and risk factors for (2) weakness at ICU discharge. Methods: Data from a randomised controlled trial that investigated two early exercise regimes in previously independent, ventilated adults (n = 115) without any significant outcome-differences were used for the present analysis. ICUAW was clinically diagnosed in cooperative participants (n = 83) at ICU discharge with the Medical Research Council sum-score (MRC-SS) using a cut-off <48 for moderate or <36 for severe weakness. Primary outcomes were the 6- Minute Walk Test and Functional Independence Measure at hospital discharge. Secondary outcomes included health-related quality of life after six months. Risk factors during the ICU stay were explored for their effect on MRC-SS with linear regression. Results: Functional outcomes and length of hospital stay significantly differed in patients with severe, moderate to no weakness (6-Minute Walk test: p = 0.013; 110m [IQR 75-240], 196m [90- 324.25], 222.5m [129-378.75], Functional Independence Measure: p = 0.001; 91[IQR 68- 101], 113[102.5-118.5], 112[97-123], length of stay after ICU discharge: p = 0.008; 20.9d [IQR 15.83-30.73], 16.86d [13.07-27.10], 11.16d [7.35-19.74]). However, after six months participants had similar values for quality of life regardless of their strength at ICU discharge (Short-Form 36 sum-scores physical health: p = 0.874, mental health: p = 0.908). In-bed immobilisation was the most significant factor associated with weakness at ICU discharge in the regression models (MRC-SS: -24.57(95%CI [-37.03 to -12.11]); p<0.001). Conclusions: In this general, critically ill cohort, weakness at ICU discharge was associated with shortterm functional disability and prolonged hospital length of stay, but not with quality of life, which was equivalent to the values for patients without ICUAW within six months. Immobilisation may be a modifiable risk factor to prevent ICUAW. Prospective trials are needed to validate these results.