Table 2.

The Severe Asthma Research Program pediatric cluster analysis: clinical characteristics of subject groups

	Spectrum of Childhood Allergic Asthma
	Mild	Moderate	Severe	Fixed Airflow
	Cluster 1	Cluster 2	Cluster 3	Cluster 4
% of all subjects in group	30	32	20	18
Severe, %	<30	50–60		>80
African American, %	31	48	59	83
Female sex, %	50		66
Asthma onset
Age, median (IQR), yr*	6 (3–9)	1 (1–4)	1 (0–1)	1 (0–2)
Relevant life events	School aged	Preschoolers	Infants	Toddlers
Atopy measures
≥1 pos SPT, %	57	83	87	89
Baseline FEV1 % predicted*	96 (82–108)	91 (80–99)	89 (75–99)	73 (64–88)
Maximal FEV1 % predicted*	109 (95–124)	103 (97–111)	99 (85–109)	91 (80–101)
Summary lung function	Normal	Normal	Obstructed, more reversible	Obstructed, less reversible
Medications, % subjects
High-dose ICS	33	59	63	83
OCS	0	8	16	10
Taking ≥3 controllers	31	71	66	83
Health care utilization, past yr, % subjects
≥3 exacerbations with OCS	65	79	72	90
Hospitalization for asthma	23	33	41	48

Definition of abbreviations: ICS = inhaled corticosteroids; IQR = interquartile range; OCS = oral corticosteroids; SPT = skin prick testing.

^*Data expressed as median (25–75% [IQR]). Table adapted with permission from Ref. 12.