Impact of the four-hour National Emergency Access Target on 30 day mortality, access block and chronic emergency department overcrowding in Australian emergency departments.

The 4HR was introduced as a means of driving hospital performance by applying a time target. Patient flow improved, but the evidence for mortality benefit is controversial with improvement only in WA. Further research with more representative data from a larger number of hospitals over a longer time across Australia is needed to increase statistical power to detect long-term effects of the policy.