Cold air challenge at age 6 and subsequent incidence of asthma. A longitudinal study.
The aim of this study was to assess the relation between bronchial hyperresponsiveness to dry, cold air at age 6 and the subsequent incidence of asthma. The cumulative incidence of newly diagnosed asthma between ages 6 and 11 among 360 children included in this study was 12.0%. Survival analysis showed that hyperresponsiveness to cold air at age 6 was associated with an increased risk of developing subsequent asthma (hazard ratio = 2.6, 95% CI = 1.2-5.4; p = 0.01). However, after adjusting for potential confounders, only mild wheezing at age 6 (adjusted hazard ratio 7.5, 95% CI = 3.6-15.9; p < 0.001) and skin test reactivity to allergens at age 6 (adjusted hazard ratio 3.6, 95% CI = 1.5-8.5; p < 0.01), but not hyperresponsiveness to cold air (adjusted hazard ratio = 0.9, 95% CI = 0.4-2.2; p = 0.8), remained significant predictors of subsequent development of asthma. These findings were substantially confirmed after stratifying for wheezing illnesses before age 3. We conclude that hyperresponsiveness to cold air at age 6 was associated with subsequent development of a diagnosis of asthma but this effect was not independent of atopy and mild wheezing at age 6.
Lombardi
E
E
Respiratory Sciences Center, University of Arizona, Tucson 85724, USA.
Morgan
W J
WJ
Wright
A L
AL
Stein
R T
RT
Holberg
C J
CJ
Martinez
F D
FD
D000367:Age Factors; D000388:Air; D001249:Asthma / Q000150:complications / Q000175:diagnosis* / Q000209:etiology; D016535:Bronchial Hyperreactivity / Q000175:diagnosis; D001985:Bronchial Provocation Tests; D002648:Child; D003080:Cold Temperature; D015986:Confounding Factors, Epidemiologic; D005260:Female; D006801:Humans; D006969:Hypersensitivity, Immediate / Q000150:complications / Q000175:diagnosis; D008137:Longitudinal Studies; D008297:Male; D016016:Proportional Hazards Models; D012135:Respiratory Sounds; D012307:Risk Factors; D012882:Skin Tests