Estimating the long-term health outcomes of treatment with lecanemab in early Alzheimer's disease: a modelling study.

AIMS: To assess the long-term effects of lecanemab plus standard of care (SoC) compared with SoC alone in a cohort of patients with early Alzheimer's disease (AD; mild cognitive impairment [MCI] due to AD, or mild AD dementia) using different modeling approaches and data from Clarity AD (NCT0388745538). METHODS: A Markov model was employed using health states based on disease severity, long-term institutionalization, and death, with disease severity defined using the Clinical Dementia Rating - Sum of Boxes (CDR-SB) classification for MCI due to AD, and Mild, Moderate, and Severe AD. State transitions during the first 18 months of treatment were estimated using either patient count data (Approach 1) or multistate survival analysis (Approach 2). Transition probabilities beyond 18 months for the lifetime of the cohort were informed by longitudinal natural history data for the SoC arm with a hazard ratio for time-to-worsening health state applied to estimate outcomes in the lecanemab arm. RESULTS: Over a lifetime horizon, the model predicted a delayed time to Mild, Moderate, and Severe AD for patients treated with lecanemab compared to SoC by 1.31, 1.85, and 2.04 years, respectively when using Approach 1. Patients treated with lecanemab experienced a survival benefit of 1.36 years, comprised of an additional 1.85 years in early AD and 0.49 years less in moderate and severe AD, compared to patients treated with SoC alone. The model also predicted that compared to SoC, lecanemab increased the time in community care and reduced time spent in institutional care. Results were similar when using Approach 2. LIMITATIONS: Long-term disease progression was informed by constant annual transition probabilities derived from the published literature. CONCLUSIONS: Patients treated with lecanemab experience delayed progression to Moderate and Severe AD, resulting in additional life-years (LYs) and reduced time in institutional care.