Measuring stroke impact with SIS: construct validity of SIS telephone administration

The purpose of this study was to examine the construct validity of the Stroke Impact Scale (SIS) using telephone mode of administration.

Stroke patients were identified using national VA administrative data and ICD-9 codes in 13 participating VA hospitals. Stroke was confirmed by reviewing electronic medical records. Patients were administered SIS by telephone at 12-weeks post-stroke, and administered the Functional Independence Measure (FIM) and SF-36V at 16 weeks post-stroke. The instrument's convergent validity and its ability to differentiate between groups of stroke patients with different disability levels were examined using Pearson's correlations and Kruskal-Wallis one way ANOVA tests.

All the relevant relationships yielded high correlation coefficients with statistical significance: 0.86 for FIM-motor vs. SIS-ADL, and 0.77 for PF in SF-36V vs. SIS-PHYSICAL. The SIS presented better score discrimination and distribution for different severity of stroke than FIM and SF-36V without severe ceiling and floor effects. Kruskal-Wallis tests showed the Physical Component Score of SF-36V did not discriminate any disability levels. Physical functioning (PF) in SF-36V, FIM-motor, SIS-PHYSICAL, SIS-16, and SIS-ADL showed better discrimination in person's functioning. The pairwise comparisons showed that SIS-PHYSICAL, SIS-16, and SIS-ADL discriminated more Rankin levels than FIM-motor and PF in SF-36V.

SIS telephone survey had superior convergent validity and was better at differentiating between groups of stroke patients with different disability levels than the FIM and SF-36V with no evidence of ceiling and floor effects. Telephone administration of SIS would be a useful and cost-effective method to follow-up community dwelling veterans with stroke.