Background:Efficient neuropsychological tests are needed to measure cognitive impairment in moderate to severe dementia.
Objective: To examine construct validity of the Severe Impairment Battery Short version (SIB-S) in nursing home patients with moderate to severe dementia, and to examine potential floor effects for the SIB-S.
Methods: Cross-sectional comparison of cognitive measures, dementia severity and functional dependency.
Results: A total of 290 patients were included of whom 264 had complete SIB-S protocols. Internal consistency of the SIB-S was very high (Cronbach’s alpha=.97). Principle components analysis produced 3 factors and the first factor explained more than 50% of common score variance. Semantic memory items loaded highly on the first factor. Total SIB-S scores were associated with cognitive impairment (SIB-S - MMSE rho = .91, p<.001), and with functional dependency (SIB-S - ADL scale rho = -.61, P<.001). SIB-S total scores differentiated between dementia severity as measured with the Global Deterioration Scale (F=164.6 df:3,260, P<.001). Comparisons of SIB-S total score variance across patients with moderate to severe dementia and patients with below or above average Mini Mental State Exam scores, support the lack of strong floor effects in the SIB-S test.
Conclusion: In this first study examining an independently administered SIB-S, the scale proved to be a homogeneous and valid measure of cognitive impairment. The SIB short version can be used to assess moderate to severely demented patients who may find it difficult to complete the traditional, lengthier neuropsychological tests.