The Competing Risk of Death in Longitudinal Geriatric Outcomes

Objectives: To address the competing risk of death in longitudinal studies of older persons, we demonstrate sensitivity analyses that evaluate robustness of associations between exposures and three outcome types: dichotomous, count, and time to event.

Design: A secondary analysis of data from a prospective cohort study.

Setting: Community-based data from the Precipitating Events Project in New Haven, CT.

Participants: Persons 70 years and older who were initially community dwelling and without disability in the four basic activities of daily living (N = 754).

Measurements: Missing outcome values from decedents were multiply imputed under different scenarios. Three outcomes were examined: dichotomous fall-related hospitalization (FRH); a count (0-13) of total disability in each of the 6 months after discharge; and days to functional recovery among those whose disability worsened in the hospital. Each outcome had a different exposure: for dichotomous, indicators of being overweight or obese; for count, frailty from the Fried phenotype (0-5, where not frail = 0, prefrail = 1-2, and frail = 3-5); for days to recovery, vision impairment.

Results: For FRH, being overweight or obese lost significance when decedents were kept in the risk pool without outcome events for over 10 years. For disability count and time to recovery, with follow-up of 6 months, exposures only lost significance under highly implausible clinical scenarios.

Conclusion: This method facilitates evaluation of potential bias from the competing risk of death in longitudinal studies for nondeath outcomes that are not necessarily time to event. Results suggest that death introduces substantive bias when long-term follow-up results in cumulatively high levels of mortality. J Am Geriatr Soc 67:357-362, 2019.