The diagnosis of pneumonia requires a chest radiograph (x-ray)—yes, no or sometimes?

Community-acquired pneumonia (CAP) remains a common condition associated with considerable morbidity and mortality. Outcome is improved by early recognition and rapid institution of empirical antibiotic therapy. A number of international guidelines recommend a chest radiograph (x-ray) is obtained when pneumonia is suspected; the argument forwarded is that chest radiographs are relatively inexpensive and enable pneumonia (lung consolidation) to be confirmed or excluded. But, radiographs are not available in the community setting and introduce a delay in diagnosis and treatment. For these reasons, in mild CAP treated by primary care, guidelines suggest criteria for clinical diagnosis. However, there is debate as to whether clinical features alone are sufficiently reliable to support a diagnosis of CAP with some suggesting diagnostic precision is improved by chest radiographs. Conversely, several studies have demonstrated a lack of agreement in the interpretation of chest radiographs bringing their role as the ultimate arbiter of diagnosis into question. Below we debate the diagnostic role of the humble chest radiograph in the context of suspected CAP.