Trajectories of Late-Life Disability Vary by the Condition Leading to Death

Background: Previous research suggested that there might be distinct patterns of functional decline in the last years of life depending on the condition leading to death, but the validity of these results and hence the explanatory value of the condition leading to death for late-life disability are uncertain. Methods: A total of 636 decedents from a cohort of 754 community-living persons, 70+ years of age (Yale PEP Study) provided 33 700 monthly observations of self-/proxy-reported disability during the last 5 years of life. Nonlinear trajectories and short-term fluctuations of late-life disability by condition leading to death (cancer, organ failure, frailty, severe dementia, sudden death, other) were estimated with flexible mixed spline regression models. Results: Disability trajectories at the end of life varied distinctively by the condition leading to death. Estimated disability trajectories among cancer deaths increased gradually up until about 6 months before death, after which a steep terminal decline set in. Among those with organ failure, frailty, and dementia, in contrast, disability was higher, increased more gradually, and there was no clear-cut terminal phase. Adding the condition leading to death to other known risk factors increased the amount of explained between-person variation in late-life disability from R-2 = 0.35 to 0.49. Short-term fluctuations in disability were not specific for decedents with organ failure. Conclusions: The condition leading to death is an important determinant of trajectories of late-life disability. These trajectories follow distinct patterns partially resembling a previously outlined theoretical typology.