Etiologies and Treatment Outcomes of Chronic Cough Diagnosed with a Pathophysiological Diagnostic Procedure: A Single-center Retrospective Observational Cohort Study.

Objective: We developed a pathophysiological diagnostic procedure to identify etiologies of chronic cough (CC) like cough variant asthma (CVA), atopic cough (AC), cough predominant asthma, sinobronchial syndrome (SBS), and mucoid impaction of small bronchi. After identifying the etiologies of CC through an understanding of its pathophysiological processes, we determined the patient's management outcomes based on the pathophysiological diagnosis.

Material and methods: In this retrospective observational cohort study, the medical records of CC patients from April 2013 to March 2018 was analyzed to assess the etiologies and treatments based on the pathophysiological diagnostic procedure. The capsaicin cough-reflex sensitivity test, methacholine-induced bronchoconstriction cough response test, bronchodilator reversibility test, bronchial responsiveness test, chest and sinus computed tomography, and sputum investigations were used for pathophysiological diagnosis.

Results: CC etiologies were diagnosed in 289 of the 298 patients who underwent the diagnostic procedures. The remaining nine patients had normal diagnostic findings. The three most common causes of CC were CVA, AC and SBS. Cough disappeared completely in 278 of the 286 patients who completed treatment. The median time to complete symptom resolution was 5.8 weeks.

Conclusion: Pathophysiological evaluation may facilitate prompt and objective diagnosis of the etiologies of CC. Our results suggest that pathophysiological diagnosis is better than the conventional diagnostic method in treatment outcomes.