[Value of exercise challenge testing in the diagnosis of cough variant asthma in children].

Objectives: To investigate the value of exercise challenge testing (ECT) in the diagnosis of cough variant asthma (CVA) in children.

Methods: A prospective study was conducted on 78 children with chronic cough who were admitted between January 2023 and January 2024. ECT was performed, and clinical data were collected. According to the effect of bronchodilator treatment, the children were divided into a CVA group (44 children) and a non-CVA group (34 children), and the two groups were compared in terms of clinical characteristics, pulmonary function, and ECT results before treatment.

Results: Compared with the non-CVA group, the CVA group had a significantly higher proportion of boys, a significantly higher proportion of children with exercise-induced chronic cough, a significantly higher level of fractional exhaled nitric oxide, and a significantly greater reduction in forced expiratory volume in 1 second (FEV₁) after ECT (P<0.05). The regression analysis showed that exercise-induced chronic cough and the reduction in FEV₁ were risk factors for CVA (P<0.05). A reduction in FEV₁ of 8.44% was the optimal cut-off value for ECT in the diagnosis of CVA, with an area under the curve of 0.751 (P<0.05), a sensitivity of 65.9%, and a specificity of 79.4%. For the children with exercise-induced chronic cough, a reduction in FEV₁ of 8.44% was the optimal cut-off value for ECT in the diagnosis of CVA, with an area under the curve of 0.810 (P<0.05), a sensitivity of 77.1%, and a specificity of 77.8%.

Conclusions: ECT has clinical application value in the etiological diagnosis of pediatric chronic cough, with a reduction in FEV1 of 8.44% serving as the optimal cut-off value for diagnosing CVA. It is particularly suitable for children with exercise-induced chronic cough, increasing the sensitivity for CVA diagnosis.