ADL disability and death in dementia in a French population‐based cohort: New insights with an illness‐death model

INTRODUCTION: Transition to bathing or dressing disability is a milestone in the evolution of dementia. We examined the transition to disability in these specific activities and considered death to be a competitive event and age and sex to be prognostic factors. METHODS: From a large cohort of 570 incident dementia cases screened in two prospective population-based cohorts, the Paquid study, and the Three-City study, we estimated the probabilities of remaining nondisabled, becoming disabled in bathing or dressing, or dying after the diagnosis using an illness-death model. RESULTS: On average, approximately half of the period (3 years) of living with dementia was free of disability. In women, a higher survival rate was associated with an average of 1 additional year with disability. DISCUSSION: The joint prediction of death and disability in dementia by an illness-death model gives original and useful parameters for the prognosis and management of dementia.