Valor diagnóstico y fiabilidad test-retest de la Escala de Demencia de Blessed (BDRS) para la enfermedad de Alzheimer: Datos del proyecto NORMACODEM

Introduction. This study aims to discover the criterion validity of the Blessed Dementia Rating Scale (BDRS) for the diagnosis of Alzheimer's disease. Different cut-off scores and corresponding diagnostic sensitivities and specificities were established. Test-retest reliability and internal consistency of the BDRS were also analyzed. Methods. Sample: 451 subjects were studied (254 controls, 86 subjects with mild cognitive impairment and 111 patients with Alzheimer's disease). Instruments: scores from different sections of the Blessed score were obtained. The global score (BBRS-Total) is the result of the sum of the three sections, A (changes in every day activities), B (changes in habits) and C (changes in personality). The sum of parts A and B (BDRS-Mod) were also quantified. Statistics: ROC curves, intraclass correlation coefficient and Cronbach's alpha. Results. The best cut-off score for the BDRS-Total was 3.5 (sensitivity: 87.39%, and specificity: 90%). For the BDRS-Mod, the best cut-off score was 1.5 (sensitivity: 90%, and specificity: 89%). Area under the ROC curve was 0.964 and 0.963 respectively. Intraclass correlation coefficient was 0.98 and Cronbach's alpha was 0.925. Conclusions. The BDRS has good discriminative validity in terms of sensitivity, specificity and predictive value. It also has good test-retest reliability and internal consistency.