Abstract
INTRODUCTION
Alzheimer disease (AD)-modifying therapies are approved for treatment of early-symptomatic AD. Autosomal dominant AD (ADAD) provides a unique opportunity to test therapies in presymptomatic individuals.
METHODS
Using data from the Dominantly Inherited Alzheimer Network (DIAN), sample sizes for clinical trials were estimated for various cognitive, imaging, and CSF outcomes.
RESULTS
Biomarkers measuring amyloid and tau pathology had required sample sizes below 200 participants per arm (examples CSF Aβ42/40: 22[95%CI 13,46], cortical PIB 32[20,57], CSF p-tau181 58[40,112]) for a four-year trial to have 80% power (5% statistical significance) to detect a 25% reduction in absolute levels of pathology, allowing 40% dropout. For cognitive, MRI, and FDG, it was more appropriate to detect a 50% reduction in rate of change. Sample sizes ranged from 75-250 (examples precuneus volume: 137[80,284], cortical FDG: 256[100,1208], CDR-SB: 161[102,291]).
DISCUSSION
Despite the rarity of ADAD, clinical trials with feasible sample sizes given the number of cases appear possible.
Full Text
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