Complex Multimorbidity and Trajectories of Functional Disabilities in the Last Three Years of Life: A Prospective Cohort Study of Older Adults in Japan

We sought to understand the impact of multimorbidity (MM) on the trajectories of functional decline in the last three years of life among older people in Japan. We used nationwide longitudinal cohort data with 6-year follow-up and analyzed 3731 functionally independent residents aged 65 years and older. The primary outcome was the five trajectory groups of functional disability in the last three years of life, defined by group-based trajectory modeling (GBTM). The explanatory variable was two alternative definitions of MM: basic MM (BMM; two or more comorbid diseases) versus complex MM (CMM; three or more body system disorders due to disease). A multinomial logistic regression analysis showed both MMs were associated with earlier trajectories of functional decline (maximum odds ratio: BMM 1.12 [0.99-1.27]; CMM 1.29 [1.16-1.44]). Preventing MMs, especially CMM, by providing appropriate care and support could contribute to healthy longevity by delaying the onset of functional disability.