Functional trajectories among older persons before and after critical illness

Abstract

Importance: Little is known about functional trajectories of older persons in the year before and after admission to the intensive care unit (ICU) or how pre-ICU functional trajectories affect post-ICU functional trajectories and death.

Objectives: To characterize functional trajectories in the year before and after ICU admission and to evaluate the associations among pre-ICU functional trajectories and post-ICU functional trajectories, short-term mortality, and long-term mortality.

Design, setting, and participants: Prospective cohort study of 754 community-dwelling persons 70 years or older, conducted between March 23, 1998, and December 31, 2012, in greater New Haven, Connecticut. The analytic sample included 291 participants who had at least 1 admission to an ICU through December 2011.

Main outcomes and measures: Functional trajectories in the year before and after an ICU admission based on 13 basic, instrumental, and mobility activities. Additional outcomes included short-term (30 day) and long-term (1 year) mortality.

Results: The mean (SD) age of participants was 83.7 (5.5) years. Three distinct pre-ICU functional trajectories identified were minimal disability (29.6%), mild to moderate disability (44.0%), and severe disability (26.5%). Seventy participants (24.1%) experienced early death, defined as death in the hospital (50 participants [17.2%]) or death after hospital discharge but within 30 days of admission (20 participants [6.9%]). Among the remaining 221 participants, 3 distinct post-ICU functional trajectories identified were minimal disability (20.8%), mild to moderate disability (28.1%), and severe disability (51.1%). More than half of the participants (53.4%) experienced functional decline or early death after critical illness. The pre-ICU functional trajectories of mild to moderate disability and severe disability were associated with more than double (adjusted hazard ratio [HR], 2.41; 95% CI, 1.29-4.50) and triple (adjusted HR, 3.84; 95% CI, 1.84-8.03) the risk of death within 1 year of ICU admission, respectively. Other factors associated with 1-year mortality included ICU length of stay (adjusted HR, 1.03; 95% CI, 1.00-1.05), mechanical ventilation (adjusted HR, 2.89; 95% CI, 1.91-4.37), and shock (adjusted HR, 2.68; 95% CI, 1.63-4.38).

Conclusions and relevance: Among older persons with critical illness, more than half died within 1 month or experienced significant functional decline over the following year, with particularly poor outcomes in those who had high levels of premorbid disability. These results may help to inform discussions about prognosis and goals of care before and during critical illness.

Figure 1. Functional Trajectories Among Older Persons in the Year Before and After Critical Illness

The number of disabilities are expressed as least squares means (95%CIs); the possible number ranged from 0 to 13. Solid lines indicate predicted functional trajectories; dashed lines, observed functional trajectories. The average posterior probability of class membership for all 3 pre–intensive care unit (ICU) functional trajectories was 98%. The corresponding probabilities for the post-ICU functional trajectories were at least 98%. Among 221 participants who survived to 30 days after ICU admission, the number (percentage) of deaths in the subsequent year was 1 (2.2%), 2 (3.2%), and 52 (46.0%) for those with minimal, mild to moderate, and severe post-ICU disability, respectively, and the median time to death was 24, 258, and 106 days, respectively.

Figure 2. Factors Associated With Short-term and Long-term Mortality After Critical Illness in Older Persons

The pre–intensive care unit (ICU) functional trajectory of minimal disability served as the reference group. The Cox proportional hazards regression model was adjusted for the first 12 factors listed in the figure. Time to death was measured from the day of hospital admission, and survivors were censored at 30 days and 1 year, respectively, for the short-term and long-term mortality models. The point estimates are accompanied by 95%CIs.