Disease Burden and Progression in Patients with New-Onset Mild Cognitive Impairment and Alzheimer's Disease Identified from Japanese Claims Data: Evidence from the LIFE Study.

Background: Accurate epidemiological data on mild cognitive impairment (MCI) and Alzheimer's disease (AD) can inform the development of prevention and control measures, but there is a lack of such data in Japan.

Objective: To investigate the disease burden and progression in patients with new-onset MCI or AD in Japan.

Methods: Using claims data, this multi-region cohort study was conducted on new-onset MCI and AD patients in 17 municipalities from 2014 to 2021. To characterize the patients, we investigated their age, comorbidities, and long-term care (LTC) needs levels at disease onset according to region type (urban, suburban, or rural). Disease burden was examined using health care expenditures and LTC expenditures, which were estimated for 1, 2, and 3 years after disease onset. Kaplan-Meier curves were plotted for AD progression in new-onset MCI patients and death in new-onset AD patients.

Results: We analyzed 3,391 MCI patients and 58,922 AD patients. In MCI and AD patients, health care expenditures were high in the first year ($13,035 and $15,858, respectively), but had declined by the third year ($8,278 and $10,414, respectively). In contrast, LTC expenditures (daily living support) steadily increased over the 3-year period (MCI patients: $1,767 to $3,712, AD patients: $6,932 to $9,484). In the third year after disease onset, 30.9% of MCI patients developed AD and 23.3% of AD patients had died.

Conclusions: This provides an important first look at the disease burden and progression of MCI and AD in Japan, which are high-priority diseases for a rapidly aging population.