Interaction between injury severity and rehabilitation intervention on independence in activities of daily living in persons with spinal cord injury

Longitudinal secondary analysis of observational data. To examine the effectiveness of physical (PT) and occupational therapy (OT) interventions in improving Spinal Cord Independence Measure III (SCIM III) scores among individuals with spinal cord injury (SCI). Two SCI centers in Japan. The content and time of rehabilitation interventions, and International Standards for Neurological Classification of SCI and SCIM III scores, were recorded at nine time points (72 h; 2, 4, and 6 weeks; and 2, 3, 4, 5, and 6 months after injury) for hospitalized individuals with SCI. Overall, 204 participants were included and categorized into four groups based on admission severity. Using a linear mixed-effects model, the effectiveness of PT and OT interventions — defined by the International Spinal Cord Injury Physical Therapy-Occupational Therapy Basic Data Set — was assessed using the SCIM III score as the dependent variable. The following items showed interaction effects between severity and treatment time for the SCIM III score: [Strength training] for PT and OT, and [Standing control activities] and [Gross motor upper extremity] for OT. Intervention effects were observed for [Bed/seated control activities], [Walking and stairs], and [Gross motor upper extremity] for PT, and [Fine motor upper extremity] for OT, regardless of severity. The results suggest that considering the interaction between injury severity and rehabilitation interventions is essential for optimizing treatment plans and determining appropriate intervention timing. These findings may support clinical decision-making and contribute to improving functional outcomes in individuals with SCI.