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Intensive care unit occupancy after introduction of the emergency department 4-hour discharge rule at a tertiary referral hospital in Western Australia.

BACKGROUND
The 4-hour rule has been introduced in Western Australia, requiring that emergency department (ED) patients be admitted to hospital or discharged from the ED within 4 hours of presentation. We hypothesised that this rule might have been associated with changes in medical emergency team (MET) calls and intensive care unit exit bed block.


METHODS
Hospital databases were examined to determine compliance with the 4-hour rule, the effect on ICU exit bed block, and the number of MET calls, in 2008 (before introduction of the 4-hour rule) and 2011 (after introduction of the 4-hour rule). We also measured background ICU and hospital activity in 2008 and 2011.


RESULTS
Monthly compliance with the 4-hour rule ranged from 35%-46% in 2008 to 64%-75% in 2011 (P < 0.0001). There was a marked increase in bed block days for patients in the ICU between 2008 (before introduction of the 4-hour rule) and 2011 (after introduction of the 4-hour rule) (P = 0.05). The increase in ICU bed block-days could not be explained by a difference in ICU occupancy, as there was a reduction in ICU bed-days between 2008 and 2011 (P = 0.014). There was a reduction in hospital mortality rate between 2008 and 2011 (P < 0.001). There was no significant increase in the number of MET calls from 2008 to 2011 (P = 0.221). Hospital activity (separations) increased from 2008 to 2011 (P < 0.0001).


DISCUSSION
The introduction of the 4-hour rule was associated with increased exit block from the ICU, but not with increased MET calls to attend to unstable or deteriorating ward patients. Introduction of the 4-hour rule was associated with a small reduction in hospital mortality.