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Evaluating the effect of clinical decision units on patient flow in seven Canadian emergency departments


Objectives — To evaluate the effect of emergency department (ED) clinical decision units (CDUs) on overall ED patient flow in a pilot project funded in 2008 by the Ontario Ministry of Health and Long-Term Care (MOHLTC).

Methods — A retrospective analysis of unscheduled ED visits at seven CDU pilot and nine control sites was conducted using administrative data. The authors examined trends in CDU utilization and compared outcomes between pilot–CDU and control sites 1 year prior to implementation, with the first 18 months of CDU operation. Sites that were unsuccessful in their applications for CDU program funding served as controls. Outcomes included ED length of stay (LOS), admission rates, and ED revisit rates.  

Results — At CDU sites, roughly 4% of ED patients were admitted to CDUs. The presence of a pilot–CDU was independently associated with a small reduction in ED LOS for all low-acuity patients (-0.14 hour, 95% confidence interval [CI] = -0.22 to -0.07) and nonadmitted patients (-0.11 hour, 95% CI = -0.16 to -0.07). A small independent effect on absolute hospital admission rate for all high-acuity patients (-0.8%, 95% CI = -1.5% to -0.03%) and moderate-acuity patients (-0.6%, 95% CI = -1.1% to -0.2%) was also observed. Pilot–CDUs were not associated with changes in ED revisit rates.

Conclusions — With only 4% of ED patients admitted to CDUs, the potential for efficiency gains in these EDs was limited. Nonetheless, these findings suggest small improvements in the operation of the ED through CDU implementation. Although marginal, the observed effects of CDU operation were in the desired direction of reduced ED LOS, reduced admission rate, and no increase in ED revisit rate.



Schull MJ, Vermeulen MJ, Stukel TA, Guttmann A, Leaver CA, Rowe BH, Sales A. Acad Emerg Med. 2012; 19(7):828-36. Epub 2012 Jul 16.

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