Risk factors for detection failures of chest radiography in diagnosing pneumonia.

Background: Little is known about clinical factors associated with undetectable pneumonic shadows on chest radiographs (CRs) for diagnosing pneumonia in the primary care setting. Methods: A retrospective assessment of CRs was conducted to compare chest computed tomography (CT) images of patients admitted to Kesennuma City Motoyoshi Municipal Hospital who were diagnosed with pneumonia from April 2014 to June 2016. Results: Eighty-three patients were included, and their average age was 83.8 years. Sixty-eight patients (81.9%) were officially certified as requiring long-term care or support. Twenty-nine of the 83 patients (34.9%) had either negative or normal findings on CRs, and positive findings consistent with pneumonia on CT. There were no significant differences in gender, age, cardiothoracic ratio on CR, or severity between the CR-negative and CR-positive groups. The proportion of negative CRs was significantly higher in patients with certified care level 5 under the long-term care system in Japan and tube feeding. Conclusion: The failure rate of CRs for detecting pneumonic shadows was significantly higher in patients with certified care level 5 and tube feeding.