Unplanned Early Readmission to the Intensive Care Unit: A Case-Control Study of Patient, Intensive Care and Ward-Related Factors (Report‪)‬

Intensive care unit (ICU) beds are a valuable commodity1,2 with considerable clinical, financial and administrative pressure to optimise their use (3-5). While ICU readmission may be associated with significant patient and healthcare costs, reliably identifying patents at risk of readmission has proved elusive. Prior studies have indicated that readmitted patients have a mortality rate of between 2 to 11 times that of non-readmitted patients and significantly greater hospital lengths-of-stay (6-8). Proposed reasons for ICU readmission include recurrence of the initial complaint (6-8), complications arising from treatment, poor responsiveness to therapy (7), comorbid complications (9), onset of new medical conditions and failure of the receiving unit to cope with the level of care demanded by the patient. Discharging patients from the ICU is, however, a complex process which is often based upon clinical judgement, the type and functionality of the institution involved and external forces such as staffing and pressure for beds. The importance of ICU readmission is underscored by the fact that unplanned ICU readmission within 72 hours of ICU discharge currently remains an Australian Council on Healthcare Standards intensive care clinical indicator for ICU performance. There have been an increasing number of studies looking at the prediction of ICU readmission (6-35). However, most have had one or more significant limitations, including a small sample, lack of a control group, no multivariate analysis and failure to examine antecedent ward-based factors. Additionally, there is a paucity of data examining this important topic from Australasia9 with the majority of key studies arising from North America7,8. With this in mind, we set out to identify patient, intensive care and ward-based risk factors for early readmission to a mixed Australian ICU over a five-year period.