Predictors of mortality in older patients following medical intensive care: the importance of functional status.
We examined predictors of hospital and 6-month mortality in older Medical Intensive Care Unit (MICU) patients with particular attention to age and functional status. Age is generally thought to be strongly associated with intensive care outcomes, but this relationship may be confounded by age-related changes. These age-related changes may be approximated by changes in functional status (FS). We conducted a retrospective chart review and collected severity of illness data using the Acute Physiology Score (APS), pre-hospitalization FS dichotomized as limited or not limited, and hospital mortality. County death records were reviewed for 6-month mortality. Three community hospital MICUs. Four-hundred MICU patients aged 50 and older admitted during the study period. Limited FS was found in 42% of the 227 patients who had FS data in the chart. Mortality was significantly associated with APS, age, FS, immunocompromise state, comorbidity, and nursing home residence. In logistic regression analyses, while controlling for important variables, APS (P less than 0.001) and age greater than or equal to 75 with limited FS (P less than 0.05) were associated with hospital mortality. Six-month mortality predictors were APS (P less than 0.001), hospital (P less than 0.05), immunocompromised state (P less than 0.05) and age greater than or equal to 75 with limited FS (P less than 0.05). We found that among patients without functional limitations, the oldest group was no more likely to die than the youngest group. Age and functional status had a significant interaction: patients older than 75 years with functional limitations were almost six times more likely to die in hospital compared to the reference group of patients between 50-64 years old without functional limitations. We conclude that functional status is an important predictor of outcome in older MICU patients.