Diagnostic accuracy of digital chest radiography for pulmonary tuberculosis in a UK urban population

To the Editors: Population screening for tuberculosis was discontinued in most Western countries, largely due to the decreasing prevalence of the disease. The use of chest radiograph examination for population screening has, therefore, appropriately declined and is now limited to the screening of high-risk groups, such as immigrants 1, prisoners or homeless persons in certain countries 2 and for disease prevalence surveys 3. Chest radiography, however, remains a key tool for the clinical diagnosis of pulmonary tuberculosis. Previous studies suggest that chest radiograph abnormalities in tuberculosis are not specific and levels of intra- and inter-reader agreement are very variable 4–6. Modern digital tuberculosis screening has been noted to have high levels of sensitivity where chest radiograph examination is standardised, quality assured and a simple coding system is used 7–9. Levels of reader agreement are also reported to be higher among experienced readers 10. In many low incidence countries, tuberculosis is concentrating in specific urban populations, such as homeless persons and drug users, with high prevalence rates reported 2, 11. In the UK, this may be contributing to the general rise in tuberculosis 12. Using a sample of digital chest radiographs from a hard to reach population at high risk of tuberculosis in London, we assessed some of the factors associated with greater diagnostic accuracy and determined levels of agreement between readers. The study was carried out in London (UK), Amsterdam and Rotterdam (the Netherlands) between July and October 2008. Of 20 physicians invited, 13 participated: three radiologists, six respiratory physicians and one infectious disease physician from London and three public health tuberculosis physicians from Amsterdam and Rotterdam. 56 randomly selected chest radiographs were chosen: 18 confirmed cases of tuberculosis, 19 other abnormalities and 19 normal films