Association of trajectories of cognitive function with cause-specific mortality and medical and long-term care costs

Abstract

Aim: Cognitive decline increases mortality risk through dementia-related pathways and might be associated with increased healthcare costs. Using up to 12 years of repeated measures data, we identified trajectories in cognitive function among community-dwelling older Japanese adults. We then examined whether these trajectories were associated with all-cause and cause-specific mortality, and differences in healthcare costs. Methods: A total of 1736 adults aged ≥65 years who were free of disabling dementia completed annual assessments during 2002–2014. Cognitive function was assessed with the Mini-Mental State Examination. The average number of follow-up assessments was 3.9, and the total number of observations was 6824 during the follow-up period. Results: We identified five trajectory patterns in cognitive function (high, second, third, fourth, and low) during the 12-year follow-up period. The low (2.0%) and fourth (2.2%) trajectory groups had higher hazard ratios for cardiovascular disease mortality, and hazard ratios for other cause mortality were significantly higher for the third (16.8%) and second (38.8%) trajectory groups than for the high trajectory group (40.3%). Until 5 years of follow up, participants in the two lower-trajectory groups had higher mean combined monthly medical and long-term care costs. After 8 years of follow up, mean costs were highest for the third trajectory. Conclusions: The risk of death from cardiovascular disease was higher in the two lower-trajectory groups in cognitive function, and they showed higher healthcare costs during the first 5 years of follow up. After 8 years of follow up, the third trajectory had the highest healthcare costs, perhaps because of hospitalizations attributable to gradual cognitive decline. Geriatr Gerontol Int 2019; 19: 1236–1242.