The Impact Treatment Imbalance and Patient Enrichment has on Study Sample Size in Early/Mild Alzheimer’s Disease

Disease modification trials in Alzheimer’s Disease (AD) are typically conducted in Early AD patients, combination of patients with mild cognitive impairment (MCI) and mild AD (mAD), despite vastly different progression rates between these two AD groups. A large sample size (SS) is required to show efficacy due to low MCI APRs. Furthermore, treatment group imbalances in patients likely to progress (PLP) may lead to underpowered studies. We quantified the impact on SS of: (1) potential treatment group imbalances in PLPs and (2) PLP enrichment strategies.