The use of a biplot in studying outcomes after stroke
Background and purpose. This study aimed to unravel the multidimensional profile of stroke outcomes by investigating the global correlation structure of motor, functional, and emotional problems of patients, as well as their caregivers' strain, at 6 months after stroke. Potential differential associations based on patients' level of functioning on admission to the rehabilitation center were analyzed. Methods. Data were collected within the CERISE-study (Collaborative Evaluation of Rehabilitation in Stroke across Europe). Six months after stroke, the Rivermead Motor Assessment (RMA), Extended Activities of Daily Living (EADL), Hospital Anxiety and Depression Scale-Anxiety (HADS-A) and Hospital Anxiety and Depression Scale-Depression (HADS-D), EuroQol-Health State (EQ-HS), EuroQol-Visual Analogue Scale (EQ-VAS), and Caregiver Strain Index (CSI) were administered. Patients were classified into 3 categories according to their Barthel Index (BI) score on admission to the rehabilitation center. Principal component analysis was carried out, and a biplot was constructed. Results. Data were available on 510 patients. One cluster was formed by RMA and EADL, and a second one by HADS-A, HADS-D, and EQ-VAS. EQ-HS was situated between these two. CSI formed a third dimension. Patients with low BI scores on admission to the rehabilitation center had higher HADS-A and HADS-D scores 6 months after stroke. High BI scores were associated with large variations in HADS-A and HADS-D scores. Conclusions. This novel biplot strategy for rehabilitation studies revealed 2 clusters: one of motor/functional problems and one of emotional problems. Patients with mild functional deficit measured on admission to the rehabilitation center can suffer from mild to severe anxiety and depression at 6 months poststroke. Screening for emotional disorders in all patients is recommended.