Muscle strength trajectories and outcomes in critically ill patients: A prospective multicentre cohort study

Abstract

Objectives: To investigate the trajectories and determinants of muscle strength in ICU patients and their impact on 1-, 6-, and 12-month mortality outcomes.

Design: Prospective multicenter cohort study.

Settings: Ten ICUs across five tertiary hospitals in Fujian Province, China.

Methods: Muscle strength was assessed using handgrip strength at three time points: ICU admission, ICU discharge, and hospital discharge. Group-based trajectory modeling was employed to identify muscle strength trajectories, while multinomial logistic analysis determined predictors based on baseline characteristics. Mortality outcomes were assessed using a Cox proportional hazards model adjusted by inverse probability of treatment weighting.

Results: Among 317 patients, with 37 deaths within 12 months, three muscle strength trajectories were identified: Low-Level Stability (38.17 %), Medium-Level Improvement (47.00 %), and High-Level Improvement (14.83 %). Older age (≥65 years), female gender, prolonged mechanical ventilation, and lower fat-free mass were associated with a higher likelihood of being in the Low-Level Stability group. After adjustment, the Medium-Level Improvement group had a 0.067 times lower 1-month mortality risk (95 % CI: 0.005-0.825) compared to the Low-Level Stability group, with no significant differences at 6 or 12 months (P > 0.05).

Conclusions: Three distinct muscle strength trajectories were identified: Low-Level Stability, Medium-Level Improvement, and High-Level Improvement. Older age, female sex, prolonged mechanical ventilation, and lower fat-free mass were strongly associated with the Low-Level Stability group, which had higher 1-month mortality.

Implications for clinical practice: Findings from this study underscore the importance of early identification of Low-Level Stability patients, particularly those who are older, female, require prolonged mechanical ventilation, or have reduced fat-free mass. Tailored early rehabilitation in these high-risk individuals may offer substantial clinical benefit.

Keywords: Critical illness; Group-based trajectory modeling; Mortality; Muscle strength.