Airway resistance and atopy in preschool children with wheeze and cough

The extent to which the measurement of airways resistance by the interrupte r technique (R-int) distinguishes preschool children with previous wheeze f rom those with no respiratory symptoms and helps to classify subjects with persistent cough, was investigated. R-int was measured before and after salbutamol treatment in 82 children wit h recurrent wheeze, 58 with isolated cough and 48 with no symptoms (control subjects). Their mean age (range) was 3.7 yrs (2-<5 yrs), Median baseline Rint was higher (p<0.0001) in wheezers than in either cough ers or control subjects (1.16, 0.94 and 0.88 kPa.L-1.s(-1) respectively); c oughers did not differ significantly from control subjects (p=0.14). The me dian ratios of baseline to post-salbutamol measurements (bronchodilator res ponse (BDR)) in the groups differed significantly (1.40, 1.27 and 1.07, p l ess than or equal to 0.01 for all), suggesting that coughers occupy an inte rmediate position. A BDR ratio of >1.22 had a specificity and sensitivity f or wheeze of 80% and 76% respectively. Twenty-eight coughers had a BDR rati o >1.22, Wheezers' immunoglobulin E was inversely related to baseline Rint, It is concluded that measurements of airway resistance by the interrupter t echnique are useful for classifying preschool children with respiratory sym ptoms and could be used to monitor the effect of interventions. The relatio n between atopy and airways resistance suggests that they have separate rol es in preschool wheezing, Coughers with a high bronchodilator response coul d represent "cough-variant" asthma in children who have baseline airway res istance by the interrupter technique measurements similar to control subjec ts. Whether these children develop classical asthma will only be known at f ollow-up later in childhood.