Hospital-Acquired Disability as a Predictor of Functional Decline in ICU Survivors: A Multicenter Prospective Cohort Study in Japan

Background: Hospital-acquired disability (HAD), defined as a decline in activities of daily living (ADL) during hospitalization, is a significant component of post-intensive care syndrome (PICS) and may influence long-term outcomes in critically ill patients. Its impact on post-discharge functional recovery, especially among patients who appear ADL-independent at discharge, remains unclear. Methods: This analysis of the multicenter prospective J-RELIFE cohort included 357 ICU patients aged ≥ 40 years who required mechanical ventilation for ≥48 h. The primary outcome was global functional decline, defined as a Kihon Checklist (KCL) score ≥ 8 at 3 months after hospital discharge. Multivariable logistic regression and Cox proportional hazards models were used to identify independent predictors of functional decline, including HAD (Δ Barthel Index ≥ 5), age ≥ 65 years, and psychological distress at discharge (Hospital Anxiety and Depression Scale ≥ 8). Results: Global functional decline at three months was observed in 45% of patients. In logistic regression analysis, HAD (OR = 1.80, 95% CI: 1.00–3.24, p = 0.049), psychological distress (OR = 2.11, 95% CI: 1.27–3.49, p = 0.004), and older age (OR = 1.03 per year, p = 0.027) were independently associated with the outcome. Relative risk analysis confirmed similar associations: HAD (RR = 1.99, 95% CI: 1.71–2.31), psychological distress (RR = 1.35), and their combination significantly increased the risk of functional decline. Among patients who were ADL-independent at discharge (Barthel Index ≥ 85), those with all three risk factors had a markedly elevated risk (RR = 10.17, 95% CI: 6.46–16.00, p < 0.001). Conclusions: HAD, older age, and psychological distress at discharge are robust predictors of functional decline after ICU discharge, even in patients who appear functionally independent at discharge. These findings support comprehensive discharge planning that incorporates both physical and psychological assessments to identify high-risk individuals and improve long-term outcomes.