Bronchodilator responsiveness and atopy in 5–10-yr-old coughers

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Abstract
Cough-variant asthma is considered by some to be an asthma phenotype. Bronchodilator responsiveness (BDR) is an undisputed feature of asthma. Of school-aged wheezers, 90% are atopic. Are school-aged coughers who demonstrate BDR also atopic? If so, then it would be reasonable to reserve the diagnosis cough-variant asthma for this particular group.Airway resistance was measured by the interrupter technique (Rint) before and after salbutamol in controls (n=73), coughers (n=63) and previous wheezers (n=63) aged 5–10 yrs. Immunoglobulin (Ig)-E was measured in coughers and wheezers. BDR was expressed as the ratio baseline:post-salbutamolRint.Groups were of similar age (mean 6.7, range 5–9.9 yrs). Geometric mean baselineRintwas similar in controls and coughers (0.66 and 0.68 kPa·L−1·s), but the baselineRintfor wheezers (0.73 kPa·L−1·s) was greater than that for controls (p=0.05) but not significantly different from coughers (p=0.17). Geometric mean BDR in coughers was 1.22, controls 1.13 and wheezers 1.30 (p=0.01 for coughers and controls; p=0.08 for coughers and wheezers; p−1, p<0.001) and was unrelated to BDR in both groups.In summary, atopy, and not bronchodilator responsiveness, distinguishes groups of coughers from groups of wheezers. A diagnosis of cough-variant asthma cannot be reserved for even those school-aged coughers, who demonstrate bronchodilator responsiveness.