. Author manuscript; available in PMC: 2011 Sep 1.

Published in final edited form as: Am J Emerg Med. 2010 Mar 25;28(7):803–808. doi: 10.1016/j.ajem.2009.04.009

Table 1.

Patient characteristics in the derivation and validation cohorts.

Variable	Derivation Cohort (n=1,825)	Validation Cohort (n=1,335)
Age, median (IQR), years	33 (24–43)	34 (23–42)
Female (%)	62	65
Ever admitted for asthma (%)	29	45
Duration of symptoms <24 hours (%)	33	48
Initial O₂ saturation on room air, median (IQR)^*	97 (95–99)	97 (95–98)
Initial respiratory rate, median (IQR), breaths per minute	20 (18–24)	24 (20–26)
Severity based on initial PEF (%)
Mild	23	15
Moderate	39	36
Severe	28	35
Very severe	10	14
Change in PEF severity category (%)^†
Improved	49	66
Unchanged	48	33
Worsened	2	1
Admission	18	21

Abbreviations: IQR, interquartile range; PEF, peak expiratory flow.

Available for 1,427 patients in the derivation cohort, and 1,119 in the validation cohort.

^†

Available for 1,159 patients in the derivation cohort, and 1,192 in the validation cohort.