Joint Trajectories of Cognition and Frailty and Associated Burden of Patient-Reported Outcomes

Objectives: To evaluate joint trajectories of cognition and frailty and their association with the cumulative burden of patient-reported outcomes, including hospitalization, nursing home admission, and disability.

Design: Longitudinal study of 754 community-living persons aged 70 or older.

Participants: 690 participants who had a baseline and at least one follow-up assessment of cognition and frailty between 1998 and 2009.

Measurements: Cognition was assessed using the Mini-Mental State Examination (MMSE). Frailty was defined by the 5 criteria for the Fried phenotype: muscle weakness, exhaustion, low physical activity, shrinking, and slow walking speed. A group-based, mixture modeling approach was used to fit the joint trajectories of cognition and frailty. The cumulative burden of hospitalization, nursing home admission, and disability over 141 months associated with the joint trajectories was evaluated using a series of generalized estimating equation Poisson models.

Results: Four joint trajectories were identified, including No cognitive frailty (27.8%), Slow cognitive decline and progressive frailty (45.5%), Rapid cognitive decline and progressive frailty (20.2%), and Cognitive frailty (6.5%). For each joint trajectory group, the interval-specific incidence density rates of all patient-reported outcomes tended to increase over time, with the exception of hospitalization for which the increasing trend was apparent only for the Slow cognitive decline and progressive frailty group. The No cognitive frailty group had the lowest cumulative burden of all patient-reported outcomes [eg, nursing home admissions, 7.5/1000 person-months, 95% confidence interval (CI): 4.8-11.7], whereas the Cognitive frailty group had the highest cumulative burden (eg, nursing home admissions, 381.1/1000 person-months, 95% CI: 294.5-493.1), with the exception of hospitalization. Compared with the No cognitive frailty group, the 3 other joint trajectory groups all had significantly greater burden of the patient-reported outcomes.

Conclusion: Community-living older persons exhibit distinct joint trajectories of cognition and frailty and experience an increasing burden of nursing home admission and disability as they age, with the greatest burden for those on a cognitive frailty trajectory.