Diagnostic Yield of Chest Radiograph in Management of Adults with Difficult-to-treat Chronic Cough—retrospective Study

Background: Chest radiograph (CXR) is a routine imaging test in adults with chronic cough (CC), while value of thoracic computed tomography (CT) in these patients is still a matter of discussion. The aims of the study were to assess the diagnostic yield of CXR and to evaluate the impact of thoracic CT on management of patients with difficult-to-treat CC referred to our cough clinic. Methods: The retrospective analysis of paired CXR and CT results was performed in 189 consecutive adults treated due to CC between 2015-2019 in our cough clinic. CC was defined as cough >8 weeks being the main or isolated ailment. The sensitivity, specificity, negative/positive predictive value (NPV, PPV) and diagnostic accuracy of CXR were calculated based on chest CT scan as the "gold standard". Only those CT scans which revealed abnormalities potentially related to CC and were associated with the changes in further diagnostic or therapeutic approach were construed as relevant CT findings during final analysis. Results: The median age of patients (male/female ratio 53/136) was 58 years (IQR 44-67), only 6 subjects (3.0%) were active smokers, median CC duration was 48 months (IQR 24-120). CXR revealed abnormal findings in 23/189 (12.2%) patients. Normal CXR was confirmed by CT in 141 subjects (141/166; 84.9%). In 25/166 (15.1%) patients, CT showed abnormalities that could explain the cause of CC and changed either the diagnostic protocol or therapy. In patients with abnormal CXR, CT confirmed abnormal findings in 8 cases (8/23, 34.8%). The sensitivity, specificity, PPV, NPV, diagnostic accuracy were 24.2%, 90.4%, 34.8%, 84.9% and 78.8%, respectively. Conclusions: CXR shows a limited diagnostic yield in adults with difficult-to-treat CC referred to cough clinic. Chest CT scan may add significant data impacting the diagnostic and therapeutic approach in these patients.