Persistent and relapsed wheezing is associated with sensitivity to domestic allergens, gender and smoking status

Abstract

Question

How common and persistent is childhood asthma? What risk factors are associated with persistence and relapse into adulthood?

Study design

Population-based study using New Zealand birth cohort from 1972 to 1973.

Main results

From childhood to 26 years, 14.5% of participants reported persistent wheezing and 12.4% episodic wheezing; 72.6% reported wheezing at some stage. Participants with persistent or relapsing wheezing were more sensitive to house dust mites and cat allergen, had more hyper-responsive airways and lower lung-function (see Table 1).

Table 1 Odds ratio (univariate analysis) for factors contributing to wheezing at 26 years compared to all other study members (except those who never reported wheezing).
	Persistent wheezing	Relapsed wheezing
	OR	95% CI	OR	95% CI
Airway hyper-responsiveness (PC20 or BDR) at 9 years	4.32	2.64 to 7.06	6.82	3.89 to 11.95
Airway hyper-responsiveness (PC20≤8 mg/ml) at 9 to 15 years	4.24	2.64 to 6.79	6.93	4.07 to 11.77
Airway hyper-responsiveness (PC20≤8 mg/ml or BDR) up to 21 years	4.13	2.59 to 6.59	7.22	4.29 to 12.17
Positive skin test for house dust mite allergen at 13 years	3.38	2.12 to 5.37	4.17	2.49 to 7.01
Positive skin test for cat allergen at 13 years	2.81	1.65 to 4.79	3.27	1.78 to 6.03
Smoking at 21 years	2.05	1.30 to 3.24	1.84	1.11 to 3.04
Age at onset of wheezing	0.97	0.94 to 1.01	0.87	0.83 to 0.91
PC20=concentration of methacholine causing a 20% decrease in forced expiratory volume in 1 s; BDR=increase from baseline in the forced expiratory volume in 1 s to a bronchodilator.

Authors’ conclusions

Childhood asthma is common. In about one in four people it persists to adulthood. Persistence and relapse are associated with airway hyper-responsiveness, allergen sensitivity, reduced lung function and smoking.