Comparison of hospital course and outcome in hospital-acquired vs pre-existing delirium.

Background: Delirium is a major source of morbidity in the inpatient hospital setting. This study examined differences between patients with delirium present prior to hospital admission and those with hospitalacquired delirium in several health outcomes.

Methods: A total of 12,529 patients on 2 inpatient units were included in this retrospective cohort study. Outcomes were assessed using chart review. Other variables were compared across groups and included in multivariate models predicting discharge location within the hospitalacquired delirium group.

Results: Of 709 patients with delirium, 83% had pre-admission prevalent and 17% had post-admission incident delirium. Compared with patients with preexisting delirium, patients with hospital-acquired delirium had greater hospital durations and mortality and were more likely to receive ICU care, more likely to receive multiple classes of medications, and less likely to be discharged home without home health services. Multivariate analysis in the hospital-acquired delirium group found that several variables independently predicted discharge location.

Conclusions: Patients with hospital-acquired delirium had worse hospital outcomes and a more complicated hospital course than those with preexisting delirium. Administration of various medications, several demographic variables, and some hospital-related variables were independently associated with worse outcomes within the hospital-acquired delirium group. These results demonstrate that patients with hospitalacquired delirium are a vulnerable subgroup deserving special attention.