Relationship between CDR Sum of Boxes and ADAS‐COG derived from historical clinical trials

Abstract

AbstractBackgroundAlzheimer’s Disease Assessment Scale, cognitive subscale (ADAS‐Cog) has traditionally been used for monitoring cognitive function in AD clinical trials, while Mini‐Mental Score Evaluation (MMSE) usually is determined at baseline. Recently however, Clinical Dementia Rating Sum of Boxes (CDR‐SOB) has become increasingly popular. We sought to define a relationship between these three clinical scales based on outcomes in clinical studies where these three scales have been used on the same patient groups.MethodWe used Certara’s CODEx (Clinical Outcomes Database Explorer) Alzheimer database, consisting now of summary endpoints in 240 clinical trials with 651 study arms (over 83300 patients) from 290 publications. 65 datasets were identified where patients were evaluated both with ADAS‐Cog and CDR‐SOB, 53 datasets for MMSE and CDR‐SOB and 167 datasets for MMSE and ADAS‐Cog.ResultStrong correlation (r2=0.8817) was observed for the relationship CDR‐SOB = 0.3105 ADAS‐Cog ‐1.1159 (p=2.2E‐16). Similarly, the relationship between ADAS‐Cog = ‐1.90881 MMSE + 62.27423 had a correlation coefficient of 0.801. Finally the linear relationship between CDR = ‐0.62806 MMSE + 18.50328 had a correlation coefficient of 0.839.ConclusionUse of the CODEx database enables to derive relationships between popular cognitive clinical scales. This would help historical clinical trials in perspective using ADAS‐Cog with more recent studies where CDR‐SOB is used as the primary outcome.