Reliability and validity of the severe impairment battery in Taiwanese patients with moderate to severe Alzheimer's disease

Background: The severe impairment battery (SIB) was developed to evaluate cognitive functions in moderate to severe dementia patients. We aimed to examine the reliability and validity of the Taiwanese version of the SIB (T-SIB) in patients with moderate to severe Alzheimer's disease (AD). Methods: AD patients with clinical dementia rating (CDR) stage 2 (n = 79) or 3 (n = 21) and scores <15 on the Taiwanese version of mini mental state examination (T-MMSE) were recruited from six hospitals in Taiwan. Cronbach's alpha was used to evaluate the internal consistency of the T-SIB. The CDR and functional assessment staging (FAST) scores were used to assess dementia severity. Results: We recruited 100 AD patients (73 women and 27 men; mean T-SIB score, 56.4 ± 24.8). The mean T-SIB total score for patients with CDR 2 and 3 were 60.3 ± 23.3 and 41.2 ± 24.9, respectively. The internal consistency of the T-SIB was 0.96. The T-SIB was moderately correlated with the T-MMSE (Pearson's correlation coefficient = 0.76). The areas under the curve for discriminating between CDR 2 and CDR 3 were 0.81 (95% CI = 0.91-0.71) and 0.72 (95% CI = 0.84-0.61), respectively. Using a cut-off score of 59, the T-SIB had a sensitivity of 80% and specificity of 61% for discriminating between CDR 2 and CDR 3. Using a cut-off score of 45, the T-SIB had a sensitivity of 83.3% and specificity of 73.1% for discriminating between the FAST stage 7c. Conclusion: T-SIB is a reliable and valid instrument for measuring cognition of severely demented Taiwanese AD patients.