Prevalence and risk factors of cough variant asthma in patients with chronic cough after COVID-19: findings from the real-world data

Chronic cough is one of the most common symptoms among post-COVID syndrome. However, limited information is available on the characteristics and possible etiology of the individuals presenting with chronic cough after COVID-19. This study aimed to investigate the prevalence and risk factors of cough variant asthma (CVA) among patients who developed chronic cough after COVID-19. In this multicenter cross-sectional observational study, a total of 530 patients who developed chronic cough after COVID-19 were included. Their demographic characteristics, clinical symptoms, comorbidities, medication history, COVID-19 vaccination history, blood laboratory findings and pulmonary function parameters were collected and summarized. The prevalence of CVA was calculated in this study, and potential risk factors associated with CVA were analyzed by logistic regression. The patients with chronic cough after COVID-19 showed a high proportion of female (69.4%) and a median age of 37 (interquartile range 27–51) years old. Of these, 96.2% were non-smokers and 74.7% had no comorbidities. CVA accounted for 30.2% of cases with chronic cough after COVID-19. Compared with non-CVA group, the patients diagnosed with CVA exhibited markedly elevated incidence of small airway dysfunction ( P < 0.001), fractional exhaled nitric oxide ( P < 0.001), peripheral blood eosinophil count ( P < 0.001) and lymphocyte count ( P = 0.012), while lung function parameters, including FEV1% predicted value, FEV1/FVC%, and PEF% predicted value, were all significantly lower (all P < 0.001). Female sex (OR 2.72, 95%CI 1.45–5.10, P = 0.002) was an independent risk factor for the occurrence of CVA after COVID-19, while COVID-19 vaccination (OR 0.32, 95%CI 0.13–0.81, P = 0.016) was identified as a protective factor for reducing the risk of CVA after COVID-19. Approximately 30% of patients who develop chronic cough following COVID-19 are newly diagnosed with CVA. Being female and lacking a history of COVID-19 vaccination are identified as independent risk factors for CVA in these patients. Not applicable.