Functional recovery and mortality after intensive inpatient rehabilitation for severe acquired brain injury in older adults: a retrospective cohort study.

BACKGROUND: Severe acquired brain injury (sABI) is a major cause of mortality and long-term disability. Although its prevalence is increasing among older adults (≥65 years), evidence on independent determinant of rehabilitation outcomes in this population remains limited. This study aimed to identify early factors associated with poor functional outcomes and mortality in younger and older patients undergoing intensive inpatient rehabilitation following severe acquired brain injury (sABI). METHODS: In this single-center, retrospective cohort study, 215 patients (91 aged ≥65; 124 aged <65) admitted to a tertiary neurorehabilitation unit were enrolled. Demographic characteristics, sABI etiology, comorbidities, dysphagia, and multidrug-resistant organism (MDRO) colonization at admission, as well as the occurrence of sepsis, hospital-acquired pneumonia (HAP), and in-hospital mortality, were evaluated. Multivariable linear regression models were used to identify factors independently associated with poorer outcomes in terms of Glasgow Coma Scale (GCS), Functional Independence Measure (FIM), and Glasgow Outcome Scale-Extended (GOS-E) scores recorded at discharge from the unit. RESULTS: Among older patients, dysphagia (FIM p < 0.0001; GOS-E p = 0.022) and diabetes mellitus (FIM p = 0.006) were associated with poorer functional outcomes after sABI. In addition, MDRO colonization at admission (p = 0.016) and sepsis (p = 0.019) were associated with worse neurological status at discharge. In younger patients, dysphagia (FIM p < 0.0001; GOS-E p = 0.002) and MDRO colonization (FIM p = 0.007) were associated with poorer functional outcomes, whereas MDRO colonization at admission (p = 0.014) and HAP (p = 0.016) were associated with worse neurological status at discharge. Despite comparable functional outcomes at discharge, older patients had significantly longer LOS (p = 0.049) and higher in-hospital mortality (34 vs. 12, p < 0.0001). HAP was the factor most strongly associated with mortality in the overall cohort. CONCLUSIONS: Dysphagia and pre-existing comorbidities, particularly diabetes mellitus, were associated with poorer rehabilitation outcomes in older patients with sABI. The association of MDRO colonization, HAP, and sepsis with poor outcomes across both age groups underscores the importance of early identification of high-risk patients and targeted preventive strategies to reduce modifiable complications, length of stay, and mortality during intensive rehabilitation after sABI.