Is a normal chest radiograph sufficient to exclude pulmonary abnormalities potentially associated with chronic cough?

There are few original studies on the true role of normal chest radiograph (CXR) in exclusion of pulmonary conditions that may be associated with chronic cough. Thus, the aim of the study was to assess whether a plain CXR is a sufficient tool to exclude relevant pulmonary causes of chronic cough.

A retrospective analysis of chest computed tomography (CT) scans in non-smoking patients with chronic cough and normal CXR was performed. The percentage of individuals in whom chest CT revealed relevant abnormalities was compared with the percentage of patients with irrelevant findings or normal chest CT scans. The negative predictive value (NPV) of the CXR in diagnosing the causes of chronic cough was calculated as a proportion of true negative CXRs (normal CXR AND irrelevant CT findings OR normal CT scan) to all negative CXRs (all patients, who had both a CXR and CT scan).

The study group consisted of 59 adult patients with chronic cough, normal CXR and CT scan performed to diagnose the cause of chronic cough. In 21 patients (21/59, 36%), chest CT revealed abnormalities that were classified as relevant to chronic cough. The most frequent were: bronchiectasis (7/59, 11.9%), bronchial wall thickening (6/59, 10.2%) and mediastinal lymphadenopathy (5/59, 8.5%). The NPV of a CXR in diagnosing the causes of chronic cough was 64%.

In conclusion, the NPV of CXR in diagnosing pulmonary causes of chronic cough is relatively low. Thus, plain CXR seems to be insufficient to exclude pulmonary diseases potentially associated with chronic cough.