[Longitudinal study of bronchial hyperreactivity using the carbachol test with school children].

STUDY DESIGN

Bronchial hyperresponsiveness of 476 schoolchildren (10.8 +/- 2.3 years) was studied three times at 12 months' intervals. The cumulative dose of 400 micrograms carbachol was applied in 50 + 50 + 100 + 200 micrograms steps. A fall of FEV1 of at least 15% was regarded as positive reaction. The test was save, as no severe obstruction was observed, only three children withdrew because of unpleasant cough.

RESULTS

Reactivity was observed in 19.1, 10.0, and 5.2% of children at the occasion of the first, second and third test (sensitivity/specificity for prevalence of physician diagnosed asthma: 70/83, 35/91, and 24/96%, respectively). Reactivity was age dependent (7-11 years: 35%, 12-16 years: 18%), not influenced by sex, and the relative risk to be reactive was 1.9 in children 2-3 weeks after a respiratory tract infection.

CONCLUSION

For epidemiological purposes carbachol provocation test--like other unspecific bronchial provocation tests--is inappropriate as a single test to classify individuals as asthmatics.