Table 1.

Subject Characteristics

	Healthy Control Subjects	Nonsevere Asthma	Severe Asthma
No.	10	9	9
Age, yr	39.0 ± 11.3	31.8 ± 16	41.4 ± 12
Sex, female/male	5/5	4/5	5/4
Duration of asthma, yr	N/A	18.2 ± 3.8	25.7 ± 9.7*
Inhaled corticosteroid dose, μg BDP equivalent	N/A	622 ± 290	2160 ± 466*
Atopy,† n	3	6	5
Receiving oral prednisolone, n	N/A	N/A	6
FEV1, L	3.15 ± 1.860	2.96 ± 0.46	2.0 ± 0.47‡
FEV1,% predicted	91.0 ± 15.6	81.5 ± 8.3	61.59 ± 4.9§
FEV1/FVC, %	77.2 ± 3.9	75.0 ± 3.1	69.0 ± 5.9*
β-Agonist reversibility, %||	N/A	24.0 ± 3.5	31.0 ± 4.11*
PC20, mg/ml	>16	2.7 ± 0.104	0.331 ± 0.13 (4/9)

Definition of abbreviations: BDP = beclomethasone dipropionate; N/A = not applicable; PC₂₀ = provocative concentration of methacholine causing a 20% fall in FEV₁.

^*P < 0.05 versus patients with nonsevere asthma.

^†Defined as positive skin prick tests to one or more common aeroallergens.

^‡P < 0.01 versus patients with nonsevere asthma.

^§P < 0.001 versus patients with nonsevere asthma.

^||Measured as percent increase in FEV₁ after 400 μg salbutamol.