Table 2.

Wheezing phenotypes and associated clinical characteristics.

	Transient wheeze	Episodic wheeze	Wheeze (Asthma*)
			Persistent	Late onset
Age
Onset	<1 year	>18 months	<1–3 years	>3 years
Remission	<4 years	<13 years	>6 years	>6 years
Risk factors	Maternal smoking	? β2ADR genotype	Atopy	Atopy
	β2ADR genotype		Family history	Family history
Factors related to viral wheeze	Mechanical (airway size or tone)	Airway tone/dysfunction	Airway/tone dysfunction	Impaired type 1 response
			Impaired type 1 response
			Early airway inflammation	Airway inflammation
BR
Birth	Increased	Normal	Normal	Normal
Childhood	Increased	Normal	Increased	Increased
Lung function
Birth	Decreased	Normal	Normal	Normal
Childhood	Decreased	Normal	Decreased	Decreased
Response to Rx
Bronchodilators	No	Yes	Yes	Yes
Inhaled CS	No	No	Yes	Yes
Symptom pattern	Episodic	Episodic	Intermittent or continuous	Intermittent or continuous
Triggers	Viruses	? Only	Viruses	Multiple
		virus infections	Multiple	+/− viruses

BR, bronchial responsiveness; β₂ADR, beta-2 adrenergic; CS, corticosteroid.

^*Associated with a family history of asthma and allergy.