Aetiologies of chronic cough diagnosed using a pathophysiologic diagnostic procedure and their treatment outcomes

Background We previously elucidated the fundamental pathophysiological features of various aetiologies of chronic cough, such as cough variant asthma, atopic cough, and sinobronchial syndrome. We also established a pathophysiological diagnostic procedure for aetiology identification. In this study, we aimed to disclose the aetiologies of chronic cough using the pathophysiological diagnostic procedure and to determine the outcomes of treatment administered on the basis of aetiology. Patients and Methods We retrospectively reviewed the medical records of patients with chronic cough who visited our cough specialty clinic from September 2013 to August 2018 and analyzed the pathophysiological diagnostic procedure-based aetiologies and corresponding treatments. The pathophysiological diagnostic procedure included the capsaicin cough test, methacholine cough test, bronchial reversibility test, bronchial responsiveness test, chest and sinus CT, and sputum examinations. Results Initially, 303 patients were selected, and 300 patients underwent the diagnostic procedure. Aetiologies of chronic cough were diagnosed in 297 patients (99.0%). In the other three patients (1.0%), all results of the diagnostic procedure were within normal limits; their aetiologies were evaluated using the therapeutic diagnostic procedure. Tweleve patients discontinued follow-up before completing treatment. Of the 291 remaining patients, cough resolved completely in 283 patients. The median time required for the complete resolution of cough was 5.0 weeks (95% CI 4.3∼5.7 weeks). Conclusions The pathophysiological diagnostic procedure can lead to rapid and objective diagnosis of causes of chronic cough, which leads to superior treatment results compared to therapeutic diagnostic procedure. Trial registration number UMIN ID: UMIN000018679 Key Messages Our pathophysiological diagnostic procedure can lead to rapid and objective diagnosis of the aetiology of chronic cough, leading to superior treatment results compared to those of therapeutic diagnostic procedures.