Does bronchial hyperresponsiveness in childhood predict active asthma in adolescence?
BACKGROUND
Bronchial hyperresponsiveness (BHR) is an important, but not specific, asthma characteristic.


OBJECTIVE
We aimed to assess the predictive value of BHR tested by methacholine and exercise challenge at age 10 years for active asthma 6 years later.


METHODS
From a Norwegian birth cohort, 530 children underwent methacholine challenge and exercise-induced bronchoconstriction (EIB) test (n = 478) at 10 years and structured interview and clinical examination at age 16 years. The methacholine dose causing 20% reduction in FEV(1) (PD(20)) and the reduction in FEV(1) (%) after a standardized treadmill test were used for BHR assessment. Active asthma was defined with at least two criteria positive: doctor's diagnosis of asthma, symptoms of asthma, and/or treatment for asthma in the last year.


RESULTS
PD(20) and EIB at 10 years of age increased the risk of asthma (β = 0.94 [95% confidence interval (CI), 0.92-0.96] per μmol methacholine and β = 1.10 [95% CI, 1.06-1.15] per %, respectively). Separately the tests explained 10 and 7%, respectively, and together 14% of the variation in active asthma 6 years later. The predicted probability for active asthma at the age of 16 years increased with decreasing PD(20) and increasing EIB. The area under the curve (receiver operating characteristic curves) was larger for PD(20) (0.69; 95% CI, 0.62-0.75) than for EIB (0.60; 95% CI, 0.53-0.67).


CONCLUSIONS
BHR at 10 years was a significant but modest predictor of active asthma 6 years later, with methacholine challenge being superior to exercise test.
Department of Paediatrics, Oslo University Hospital, NO-0407 Oslo, Norway. amund.riiser@gmail.com
Amund
A
Riiser
Vegard
V
Hovland
Kai-Håkon
KH
Carlsen
Petter
P
Mowinckel
Karin C
KC
Lødrup Carlsen
D000293:Adolescent; D000367:Age Factors; D001249:Asthma / Q000175:diagnosis* / Q000188:drug therapy / Q000453:epidemiology*; D001250:Asthma, Exercise-Induced / Q000175:diagnosis / Q000188:drug therapy / Q000453:epidemiology; D016535:Bronchial Hyperreactivity / Q000175:diagnosis* / Q000188:drug therapy / Q000453:epidemiology*; D001985:Bronchial Provocation Tests / Q000379:methods*; D002648:Child; D015331:Cohort Studies; D018450:Disease Progression; D005080:Exercise Test / Q000379:methods*; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D053208:Kaplan-Meier Estimate; D008297:Male; D016210:Methacholine Chloride; D015999:Multivariate Analysis; D016017:Odds Ratio; D011237:Predictive Value of Tests; D015995:Prevalence; D011446:Prospective Studies; D012372:ROC Curve; D012129:Respiratory Function Tests; D018570:Risk Assessment; D012737:Sex Factors; D011795:Surveys and Questionnaires; D013997:Time Factors
D016210:Methacholine Chloride