Evaluation of Flortaucipir PET Signal and Cognitive Change in Early Alzheimer's Disease

Baseline flortaucipir F 18 PET imaging results were determined by majority read (see Baseline Characteristics for description). Clinically meaningful deterioration (CMD) was defined for the primary endpoint as a worsening of the Clinical Dementia Rating Scale Sum of Boxes (CDR-SB) score of one point or more. The clinical dementia rating (CDR) examines 6 categories of cognitive functioning domains. Each domain is scored on a scale ranging from 0 to 3 (including 0.5). A CDR-SB was generated as the sum of the values in each of the 6 domains. The CDR-SB sum scores range from 0 to 18, with higher scores indicating greater cognitive impairment and a 1 point worsening is considered a clinically significant symptom change.

Baseline flortaucipir F 18 PET imaging results were determined by majority read (see Baseline Characteristics for description). Clinically meaningful deterioration (CMD) was defined for the cognitive endpoints as follows: mini-mental status exam (MMSE) worsening of 3 points or greater, Alzheimer's Disease Assessment Scale-Cognitive Subscale (ADAS-Cog11) worsening of 4 points or greater, Pfeffer's Functional Activities Questionnaire (FAQ) worsening of 3 points or greater, CDR global worsening of greater than 0 points. MMSE scores range from 0 to 30 with lower scores indicating worsening cognitive function. ADAS-Cog11 scores range from 0 to 70 with higher scores indicating worsening cognitive function. FAQ scores range from 0 to 30 with higher scores indicating worsening cognitive function. CDR global is scored on a 5 point scale (0, 0.5, 1, 2, 3) with higher scores indicating worsening cognitive function.

Mean change in cognitive/functional measures baseline between τAD++ and non-τAD++ (determined by baseline tau status), calculated by Mixed Model Repeat Measures (MMRM). CDR-SB scores range from 0 to 18, with higher scores indicating worsening cognitive impairment. MMSE scores range from 0 to 30 with lower scores indicating worsening cognitive function. ADAS-Cog11 scores range from 0 to 70 with higher scores indicating worsening cognitive function. FAQ scores range from 0 to 30 with higher scores indicating worsening cognitive function.

As measured by Fleiss' Kappa across all scans read. Fleiss' kappa is a statistical measure for assessing the reliability of agreement between a fixed number of raters when assigning categorical ratings to a number of items or classifying items. Fleiss' kappa can range from -1 to 1 with 1 indicating perfect agreement between the readers. Read results binarized as τAD++ or non-τAD++.