Mobility Trajectories at the End of Life: Comparing Clinical Condition and Latent Class Approaches.

Objectives: To assess mobility disability trajectories before death in a large sample of very old adults using two analytical approaches to determine how well they corresponded.

Design: Decedent sample from the Health, Aging and Body Composition (Health ABC) Study. Data were collected between 1997 and 2015.

Setting: Pittsburgh, Pennsylvania, and Memphis, Tennessee.

Participants: Individuals randomly selected from well-functioning white Medicare beneficiaries and all black community residents meeting age criteria (70-79) (N = 3,075).

Measurements: Participants were interviewed in person or by phone at least every six months throughout the study. Of the 1,991 participants who died by the end of the study, 1,410 had been interviewed for 3 years before death, including an interview 6 months before dying. We analyzed self-reported mobility collected prospectively at 6-month intervals during the last 3 years of life. We derived trajectories in two ways: by averaging decline within decedent groups prespecified according to clinical conditions and by estimating trajectory models using maximum-likelihood semiparametric modeling.

Results: Ninety-eight percent of decedents were classified according to 4 prespecified clinical conditions (sudden death, terminal, organ failure, frailty), which produced groups with different characteristics. Five disability trajectories were identified: late decline, progressive disability, moderate disability, early decline, and persistent disability. Disability trajectory and clinical condition grouping confirmed previous research but were only marginally related.

Conclusion: Derived disability trajectories and grouping according to clinical condition provide useful information about different facets of the end-of-life experience. The lack of fit between them suggests a need for greater attention to heterogeneity in disability in the period before death.