Measuring and predicting long-term outcomes in older survivors of critical illness.

Older adults (age ≥65 years) now initially survive what were previously fatal critical illnesses, but long-term mortality and disability after critical illness remain high. Most studies show that the majority of deaths among older ICU survivors occur during the first 6 to 12 months after hospital discharge. Less is known about the relationship between critical illness and subsequent cause of death, but longitudinal studies of ICU survivors of pneumonia, stroke, and those who require prolonged mechanical ventilation suggest that many debilitated older ICU survivors die from recurrent infections and sepsis. Recent studies of older ICU survivors have created a new standard for longitudinal critical care outcomes studies with a systematic evaluation of pre-critical illness comorbidities and disability and detailed assessments of physical and cognitive function after hospital discharge. These studies show that after controlling for pre-morbid health, older ICU survivors experience large and persistent declines in cognitive and physical function after critical illness. Long-term health-related quality-of-life studies suggest that some older ICU survivors may accommodate to a degree of physical disability and still report good emotional and social well-being, but these studies are subject to survivorship and proxy-response bias. In order to risk-stratify older ICU survivors for long-term (6-12 months) outcomes, we will need a paradigm shift in the timing and type of predictors measured. Emerging literature suggests that the initial acuity of critical illness will be less important, whereas prehospitalization estimates of disability and frailty, and, in particular, measures of comorbidity, frailty, and disability near the time of hospital discharge will be essential in creating reliable long-term risk-prediction models.