Association between changes in disease severity and physical function after surviving a critical illness: A multicentre retrospective observational study

Background: Whilst disease severity can significantly impact functional outcomes, the ability to predict the scale of this impact has not been consistent.

Aim: We aimed to investigate whether changes in disease severity within the first 48 h of ICU admission are more strongly associated with physical dysfunction than a single-time assessment of disease severity at ICU admission.

Methods: A multicentre retrospective study in seven tertiary ICUs in Japan, including all consecutive adult ICU patients (>48 h ICU stay) between September 2019 and February 2020. The primary outcome was physical function defined as the Barthel Index, which is an ordinal scale (0-100: larger indicates better function) to measure physical independence and performance. The association between Barthel Index score at hospital discharge and the Sequential Organ Failure Assessment (SOFA) scores, measured at ICU admission, the highest recorded score within 48 h of ICU admission, and the level of change between these two timepoints were investigated in multivariable analysis.

Results: A total of 199 patients were included. Median SOFA score at ICU admission and the highest recorded score within the first 48 h were 6 (interquartile range: 5-10) and 8 (interquartile range: 6-11), respectively. A quarter of patients had a Barthel Index score of 60 or less at hospital discharge. The highest SOFA score within 48 h of ICU admission and the level of change in SOFA scores between ICU admission and the highest recorded score within 48 h were significantly associated with lower Barthel Index scores at hospital discharge. No significant association was identified with regard to Barthel Index scores and SOFA score at ICU admission. An increase in SOFA score of 1 or more within the first 48 h of ICU admission was the threshold to predict a Barthel Index score of 60 or less at hospital discharge. Larger changes in SOFA scores over the first 48 h of ICU admission were also significantly associated with smaller changes in Barthel Index scores from ICU discharge to hospital discharge.

Conclusions: The level of change in SOFA score between ICU admission and the highest recorded score within the first 48 h of ICU stay can more accurately predict the presence of physical dysfunction at hospital discharge than a single-time assessment of disease severity at ICU admission. The larger worsening in SOFA potentially indicates lower recovery after a critical illness.