Frailty Trajectories in an Elderly Population-Based Cohort

Abstract

Objectives: To identify distinct frailty trajectories (clusters of individuals following a similar progression of frailty over time) in an aging population and to estimate associations between frailty trajectories and emergency department visits, hospitalizations, and all-cause mortality.

Design: Population-based cohort study.

Setting: Olmsted County, Minnesota.

Participants: Olmsted County, Minnesota residents aged 60-89 in 2005.

Measurements: Longitudinal changes in frailty between 2005 and 2012 were measured by constructing a yearly Rockwood frailty index incorporating body mass index, 17 comorbidities, and 14 activities of daily living. The frailty index measures variation in health status as the proportion of deficits present of the 32 considered (range 0-1).

Results: Of the 16,443 Olmsted County residents aged 60-89 in 2005, 12,270 (74.6%) had at least 3 years of frailty index measures and were retained for analysis. The median baseline frailty index increased with age (0.11 for 60-69, 0.14 for 70-79, 0.19 for 80-89). Three distinct frailty trajectories were identified in individuals aged 60-69 at baseline and two trajectories in those aged 70-79 and 80-89. Within each decade of age, increasing frailty trajectories were associated with greater risks of emergency department visits, hospitalization, and all-cause mortality, even after adjustment for baseline frailty index.

Conclusion: The number of frailty trajectories differed according to age. Within each age group, those in the highest frailty trajectory had greater healthcare use and worse survival. Frailty trajectories may offer a way to target aging individuals at high risk of hospitalization or death for therapeutic or preventive interventions.

Keywords: aging; frailty; longitudinal studies; population research.

Figure 1. Frailty trajectory plots in the 60–69, 70–79, and 80–89 year old age groups

The black line indicates the lowest trajectory, the green line indicates the middle trajectory, and the red line indicates the highest trajectory. The percentage next to each trajectory indicates the proportion of individuals in that trajectory.