Figure 1.

Patient enrollment. The ED admitted 4,411 patients from 5 February 2011 to 8 April 2011 (63 days). Based on simple proportions, we estimate that 1,179 patients were admitted during our recruitment blocks [4411 × (101*4)/(63*24) h]. Of these, 443 (38 %) were assessed for eligibility and approached for enrollment. (Note that 1,179 is likely an underestimate and 38 % a corresponding overestimate given that we did not enroll patients between 11 p.m. and 7 a.m., when admission rates are lower.)