The Stroke Impact Scale: validation in a UK setting and development of a SIS short form and SIS index.

BACKGROUND AND PURPOSE: The Stroke Impact Scale (SIS) covers 8 dimensions and a composite disability score. This study evaluates the SIS in the UK context, and develops a single index and an 8-item short form. METHODS: Patients with a diagnosis of stroke were recruited through general practices in London and the North-West of England. Patients completed the SIS and the EQ-5D. RESULTS: Internal consistency of the SIS dimensions and the disability score ranged from α 0.86 to 0.95. Complete data were available on 73 questionnaires (48.34%). Factor analysis suggested the 8 domains could be aggregated into a single index. A short-form SIS (SF-SIS) index was created by summing 1 item per dimension. Selected items were those that most highly correlated with their respective domain score (ρ ranged from 0.77-0.94, P<0.001). The SF-SIS index scores were highly correlated with those gained from the parent form (ρ=0.98; P<0.001). The correlation of the SIS index and SF-SIS index with the EQ-5D was identical (ρ=0.83; P<0.001). The disability score, whether scored from the dimensions of the SIS, or relevant items on the SF-SIS, were highly correlated (ρ=0.97; P