B – 157 Diagnostic Accuracy of the Clinical Dementia Rating Scale in Distinguishing MCI from Dementia Across Racial/Ethnic Groups

Abstract Objective The Clinical Dementia Rating (CDR) Scale evaluates dementia severity and progression across cognitive and functional domains, with the CDR Sum-of-Boxes (CDR-SB) score serving as a key outcome measure in Alzheimer’s disease (AD) clinical trials. As such, exploration of its diagnostic accuracy in racially and ethnically diverse populations is essential to ensure equitable measurement of treatment outcomes. Method Community-dwelling adults diagnosed with mild cognitive impairment (MCI; n=777) or dementia (n=232) were sampled from the Health & Aging Brain Study–Health Disparities (HABS-HD), including 270 non-Hispanic Whites (NHW), 374 non-Hispanic Blacks (NHB), and 365 Mexican Americans (MA). Receiver operating characteristic (ROC) curves evaluated the ability of a modified CDR-SB (derived from informant interview data and participant orientation responses from a cognitive screener) to distinguish clinically diagnosed MCI from dementia in NHW, NHB, and MA groups. Results ROC curves and corresponding area under the curve (AUC) values demonstrated outstanding diagnostic performance among the NHW group (AUC=0.94, sensitivity=0.94, specificity=0.88), and excellent performance among NHB (AUC=0.87, sensitivity=0.87, specificity=0.83) and MA (AUC=0.90, sensitivity=0.93, specificity=0.83) groups. The NHW group exhibited a significantly higher AUC than the NHB group (0.94 vs. 0.87, p=0.04). Youden's Index indicated an optimal CDR-SB cut-off of 2 for distinguishing MCI from dementia across all three racial/ethnic groups. Conclusions Findings support the modified CDR-SB as a useful tool for differentiating MCI from dementia among racial/ethnic groups. However, its differentiation was lower in NHB individuals, suggesting it may not equally capture functional or cognitive changes. Future research should examine potential sources of bias to improve generalizability to diverse populations.