Delirium in patients admitted to a step-down unit: analysis of incidence and risk factors

Delirium is a rather common complication among patients admitted in intensive care units (ICUs), and rather than a single entity, it can be considered a spectrum of diseases where, besides overt cases, there are also many subsyndromal forms. Although there are many data about ICU delirium, there are few data concerning this complication in patients transferred from the ICU to a step-down unit (SDU) once clinically stable.

With the present study, we wanted to assess the incidence of and risk factors for delirium and subsyndromal forms and their impact on clinical outcome in a group of patients transferred from an ICU to an SDU.

All patients transferred from an ICU to our SDU over a 2-year period were screened for delirium and subsyndromal delirious forms using the Intensive Care Delirium Screening Checklist, a simple tool already validated in the ICU. The following data were also recorded: demographic data, severity score (SAPS II), reason for admission to the SDU, length of stay, death rate, use of sedatives, impact of delirium on weaning from mechanical ventilation (MV).

Among the 234 patients, the incidence of delirium and subsyndromal forms was 7.6% and 20%, respectively. Subsyndromal forms diagnosed at admission represented a risk factor for the subsequent development of delirium (odds ratio [OR], P < .0001). A previous episode of brain failure during ICU stay and older age were risks factors for the development of subsyndromal forms, whereas not needing MV was a protective factor. Delirium significantly prolonged the stay in the SDU but did not influence survival and the process of weaning from MV. Overall, the percentage of patients with an abnormal Intensive Care Delirium Screening Checklist score at discharge (5%) was reduced compared with that recorded at admission (18%).

Delirium may still occur after discharge from an ICU in patients who are transferred to an SDU. The strategy of care adopted in the SDU seems to positively affect the recovery from a delirious state. Patients with subsyndromal forms should be promptly recognized and treated because of the risk of developing delirium. Weaning from MV is not hindered by delirium.