The effect of context on performance of an acute medical unit: experience from an Australian tertiary hospital.

Objective. To ascertain the improvements in length of stay and discharge rates following the opening of an acute medical unit (AMU). Methods. Retrospective cohort study of all patients admitted under general medicine from June-November 2008. Main outcome measures were length of stay in hospital and in the emergency department (ED). Results. The length of time spent in the emergency department for those admitted to the AMU was significantly shorter than those admitted directly to a medical ward (6.83h v. 9.40h, P<0.0001). A trend towards shorter hospital length of stay continued after the AMU opened compared with the same period in the previous year (5.15 days (2.49, 11.57 CI) v. 5.66 days (2.76, 11.52 CI)). However, the number of ward transfers for a patient and the need to wait for a nursing home bed or public rehabilitation affected length of stay much more than the AMU. Conclusion. An AMU was successful in decreasing ED length of stay and contributed to decreasing hospital length of stay. However, we suggest that local context is crucially important in tailoring an AMU to obtain maximal benefit, and that AMUs are not a 'one size fits all' solution. What is known about the topic? Acute Medical Units were pioneered in the UK and have been shown to decrease length of stay with no increase in adverse events. As a result, they have been enthusiastically adopted in Australia. However, most studies have been single point 'before/after' designs looking at all medical patients, and there has been little consideration of the context in which AMUs operate and how this might affect their performance. What does this paper add? We consider length of stay trends over many years and separate single organ disease from multi-system disease patients, in order to ensure that gains are not simply a result of selective entry of healthier patients into AMUs. We also show that the effect of an AMU is small compared with other systemic issues, such as waiting for nursing home placement and the number of transfers of care. What are the implications for practitioners? Although there may be gains in terms of length of stay in the emergency department, those considering the establishment of an AMU need to consider other factors that may mitigate the improvements in hospital length of stay, such as the roadblocks to discharge, the organisation of allied health staff, and the number of transfers of care. [ABSTRACT FROM AUTHOR]