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

Abstract

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 film

Inter-Observer Variability in the Detection and Interpretation of Chest X-Ray Anomalies in Adults in an Endemic Tuberculosis Area

“…Disagreements were common in the detection of pleural effusions in contrast to the results from Shinsaku et al [5] in Japan and Abubakar et al [24] in London who found a moderate to excellent level of agreement. The predominance of low abundance pleural effusions in our sample (n = 5/6) and their association with other abnormalities could explain these disconcordances.…”

“…For the detection of ADP, inter-observer agreement was good (K = 0.61) between pneumologists and moderate (K = 0.55) between radiologists. In a similar study conducted in 2010 in London, Abubakar et al [24] reported a poor agreement between both pneumologists and radiologists. The frequent association of ADP with pulmonary tuberculosis and the high prevalence of tuberculosis in our environment could explain this difference.…”

“…Dawson et al reported a good agreement between radiologists in South Africa in 2010 [27]. Abubakar et al [24] observed a moderate agreement for both radiologists and pneumologists. Balabanova et al [10] had reported a poor agreement between pneumologists and moderate between radiologists.…”

Diagnostics for pulmonary tuberculosis

“…By limiting suspects to those with typical infiltrates, the sensitivity dropped to 73% 20. In a study from the UK, Amsterdam and Rotterdam looking at newer digital chest X-ray technology, the sensitivity of radiologists and chest physicians for detecting culture-positive TB on chest X-ray was a similar 77% 21. HIV-coinfected TB patients are less likely to have typical chest X-ray infiltrates, especially with declining CD4 cell counts 22.…”

Inter-rater agreement in the assessment of abnormal chest X-ray findings for tuberculosis between two Asian countries

“…Previous studies suggest that variability in CXR interpretation among raters is attributed to subjective reading accompanied by insufficient experience or different professional background of the raters [7,10-12]. However, the relationship between agreement levels and relevant factors that may cause disagreement, particularly influence of medical background including different national origins has not been characterized.…”