Using Latent Growth Curve Modeling to Reexamine Determinants of Functional Disability Progression

Objective. Our aim was to use latent growth curve modeling to reexamine the influences of six determinants on older adults’ baseline general functional disability and change in general functional disability over time.

Methods. The study analyzed the relationships between six related demographic and pathological determinants and older adults’ general functional disabilities using a longitudinal and nationally representative survey database, Health and Living Status of the Middle Aged and Elderly in Taiwan. Four waves of survey data, from 1996 to 2007, and 3,186 older adults were included for analysis. General Functional disability trajectories were modeled using Nagi’s functional limitations, activities of daily living, and instrumental activities of daily living.

Results. Education was negatively associated with both baseline (β = −.091***) and change in (β = −.085***) general functional disability. Being older (β = .430***), being female (β = .106***), and having a greater number of comorbidities (β =.127***) were positively associated only with a faster increase in general functional disability. Better self-rated health (β = −.260***) and depression CES-D score (β = −.183***) were significantly associated only with baseline functional disability.

Conclusion. Study findings further refined our understanding that some determinants are important only to concurrent baseline general functional disability, while others are more important to future faster increase in functional disability. For example, age alone may not necessarily be a determinant of baseline functional disability, but increased age brings a risk of faster increases in functional disabilities that have already developed.