P182 Follow up chest X-rays (CXR) after community acquired pneumonia (CAP): are they done and are they useful?

Abstract

Introduction It has become regular practice to arrange repeat CXRs for patients diagnosed with CAP. The British Thoracic Society (BTS) recommend follow up CXRs at around 6 weeks for all patients who have persisting signs or symptoms and those who have risk factors for underlying malignancy. They place particular emphasis on patients who are smokers or are over the age of 50. Ionising radiation poses a risk to patients, and follow up CXRs often lead to further radiation in the form of CT imaging. We aim to assess whether radiation exposure from repeat CXRs (0.02 mSv) and CT thorax imaging (7.0 mSv) is justified, and how many underlying malignancies are identified as a result of repeat imaging. Methods This retrospective study identified patients with radiologically diagnosed CAP referred from the medical assessment unit. Patients with known lung cancers were excluded. Taking particular note of those deemed high risk by the BTS we aimed to quantify those who have follow up imaging and those who had since been diagnosed with an underlying malignancy. Results 119 patients were identified. 117 of the patients (98%) were either over the age of 50 or smokers and therefore deemed high risk by the BTS. Only 65 (55%) had follow up imaging and of those with follow up, 5 patients (8%) were later diagnosed with an underlying malignancy (3 new lung primaries, 1 metastasis, 1 myeloma). 14 patients had CT imaging of the chest, 10 of these following a repeat CXR. None of the 4 CT scans requested prior to repeat CXRs identified an underlying malignancy. Conclusion The risk of radiation exposure for repeat CXRs following CAP is easily justified. The vast majority of patients (98%) who are diagnosed with CAP have a significant risk factor for underlying malignancy but only 55% had follow up CXRs. This has highlighted the need for a more efficient system to ensure follow up CXRs are being performed. A larger study is required to accurately assess whether exposing patients to CT imaging is justified and if follow up CXRs are beneficial in those without risk factors.