Use of the SONET Score to Evaluate High Volume Emergency Department Overcrowding: A Prospective Derivation and Validation Study

Table 4

Comparison of the average length of stay in patients with different acuity levels under different ED overcrowding status determined by the NEDOCS score in the derivation study.

ED crowding status	ESI-1 (h); Mean (SD) ()	ESI-2 (h	ESI-3 (h)	ESI-4 (h)	ESI-5 (h)
Patients that were discharged from ED (number of patients)
Not overcrowded	5.58 (1.35); (5)	4.68 (2.46); (130)	4.26 (2.63); (461)	2.99 (1.76); (259)	2.11 (1.36); (76)
Overcrowded	5.19 (2.31); (9); (1.000)	4.72 (2.55); (158); (1.000)	5.19 (2.91); (415); (<0.001)	3.52 (1.69); (314); (0.006)	2.88 (1.17); (53); (0.026)
Severely overcrowded	5.04 (2.21); (13); (1.000)	5.17 (3.40); (335); (0.386)	6.53 (3.31); (809); (<0.001)	4.69 (2.34); (491); (<0.001)	3.91 (1.98); (97); (0.001)
All patients that were initially registered at ED (number of patients)
Not overcrowded	5.24 (5.46); (36)	5.86 (3.53); (266)	5.10 (3.70); (623)	3.23 (2.31); (282)	2.26 (1.52); (86)
Overcrowded	5.33 (4.57); (49); (1.000)	6.50 (4.61); (368); (0.338)	6.38 (4.55); (642); (<0.001)	3.82 (2.33); (352); (0.016)	2.97 (1.68); (63); (0.165)
Severely overcrowded	6.02 (6.02); (115); (1.000)	7.38 (5.69); (716); (0.020)	7.09 (4.55); (1295); (0.002)	5.04 (2.94); (644); (<0.001)	4.33 (2.78); (134); (<0.001)

ESI: emergency severity index; Mean: the average of length of stay (LOS) in hours; SD: standard deviation; : the number of patients. value of the comparison between two groups of patients under the different ED crowding conditions (not overcrowded versus overcrowded). value of the comparison between two groups of patients under the different ED crowding conditions (overcrowded versus severely overcrowded).