Value of surrogate tests to predict exercise-induced bronchoconstriction in atopic childhood asthma.
Exercise challenge tests are helpful in the diagnosis and management of childhood asthma, but methodology is complex and time-consuming. The aim of this study was to investigate whether exercise-induced bronchoconstriction (EIB) can be predicted by the results of different surrogate tests in a pediatric population. Eighty-five children (mean age: 11 years, range: 5-16 years) with atopic asthma were studied. Measurements of exhaled nitric oxide (eNO), spirometry and whole body plethysmography were performed followed by a standardized exercise testing. Questionnaires were completed asking for respiratory symptoms within 2 weeks preceding the study protocol. In 12/85 children (14%), forced expiratory volume in 1 sec (FEV1) was significantly reduced by > or = 15% after exercise testing. eNO was significantly elevated in this group of 12 patients as compared to patients without EIB (51.3 (31.1-67.3) parts per billion (ppb) versus 20.2 (10.9-42.3) ppb; P = 0.003). All children with normal eNO levels (< or = 25 ppb) had normal lung function results after exercise; hence the negative predictive value (NPV) of elevated eNO levels for prediction of EIB was 100%. However, the positive predictive value (PPV) was only 28%. The NPV and PPV for reported asthma symptoms within 2 weeks preceding the study were 96% and 26%, respectively. Considering recent symptom history in addition to elevated eNO improved the PPV to 40%, and resulted in the best combination of sensitivity and specificity. No baseline lung function parameter predicted whether a patient would develop EIB or not. In conclusion, eNO measurements, symptom questionnaires and most efficiently a combination of both surrogate tests can be used as time-saving methods to exclude EIB in atopic childhood asthma.
Lex
Christiane
C
Department of Paediatric Cardiology and Pulmonology, Heinrich-Heine-University, Düsseldorf, Germany. lex@med.uni-duesseldorf.de
Dymek
Sabine
S
Heying
Ruth
R
Kovacevic
Alexander
A
Kramm
Christof M
CM
Schuster
Antje
A
D000293:Adolescent; D001249:Asthma / Q000378:metabolism / Q000503:physiopathology*; D016084:Bronchoconstriction; D002648:Child; D002675:Child, Preschool; D005080:Exercise Test; D045853:Exhalation; D005260:Female; D006801:Humans; D008297:Male; D009569:Nitric Oxide / Q000032:analysis; D011237:Predictive Value of Tests; D012129:Respiratory Function Tests
D009569:Nitric Oxide