this study aimed to compare characters in pulmonary function of patients with cough variant asthma and chronic cough and establish a diagnostic model.

the investigators retrospectively collected information from patients with chronic cough who underwent pulmonary tests at the First Affiliated Hospital of Zhejiang Chinese Medical University from January 2019 to December 2019. Data of external test were also from the First Affiliated Hospital of Zhejiang Chinese Medical University, and time period was from January 2023 to April 2023.Pulmonary function test and methacholine challenge test was performed by professional technicians. Characters between patients with cough variant asthma and chronic cough were compared to establish a diagnostic model.

Inclusion Criteria:

• (1) age from 18 years old to 65 years old; (2) clinical diagnosis of CVA and CC .

Exclusion Criteria:

• Exclusion criteria for CVA were: a history of COPD, bronchiectasis, bronchitis, cystic fibrosisor pneumonia, interstitial lung disease, pulmonary tuberculosis, lung cancer; cough caused by drugs or treatments; patients with upper airway cough syndromes (UACS) and gastroesophageal reflux-related cough (GERC) or other apparent causes of cough; patients who used corticosteroid (ICS) in the previous four weeks; Exclusion criteria for CC were: a history of variable airway limitation.

We retrospectively collected information from patients with CC who underwent pulmonary tests at the First Affiliated Hospital of Zhejiang Chinese Medical University from January 2019 to December 2019.