RESPONSE-DOSE RATIO AS AN INDEX OF BRONCHIAL RESPONSIVENESS TO HYPERTONIC SALINE CHALLENGE IN AN EPIDEMIOLOGIC SURVEY OF ASTHMA IN POLISH CHILDREN

This epidemiological survey was done to evaluate the bronchial respons iveness (BHR) to a 4.5% hypertonic saline (HS) challenge in 13-14 year -old schoolchildren. BHR was measured by the response-dose ratio in wh ich the response was estimated by the decline of FEV, index of BHR (Ix FEV(1)). Validity of the HS challenge test as a screening test for con firmation of reported asthma symptoms and the diagnosis of asthma was assessed. With a cutoff of 90th percentile of IxFEV, in controls, the test sensitivity and specificity for asthma symptoms in the last 12 mo nths was 44% and 90%, respectively. For the diagnosis of asthma the te st sensitivity was 67% and specificity 90%. The mean log transform of IxFEV, was significantly higher in children with more than three episo des of wheezing in the last 12 months and a diagnosis of asthma than i n controls. Moreover, in the group with more than three episodes of as thma in the last 12 months the mean IxFEV, was higher in girls than in boys. There was no gender difference in other groups of asthmatic chi ldren and controls. In Polish schoolchildren the prevalence of BHR to HS was 12.5% when adjusted to the prevalence of wheezing in the last 1 2 months. By multiple linear regression analysis, factors associated w ith BHR were serum levels of total IgE in children and of maternal IgE , as well as children's peripheral blood eosinophil counts. Also, the size of skin reaction to mite and dog allergens correlated with BHR. ( C) 1998 Wiley-Liss, Inc.