In conclusion, the previously documented higher accuracy of HRCT scans compared with chest radiographs in the detection of active pulmonary TB4 is again noted in this study. However, as a result of study design and the methodologic flaws described previously, the aim of the study to elucidate the role of HRCT scanning in outbreak investigation is not met. The conclusion that HRCT scans may differentiate active TB from latent TB infection in outbreak investigation is insufficiently supported by the data. As the authors mention in their discussion, the impact of additional HRCT scanning in TB outbreak investigation can only be assessed by randomized controlled trials with the incidence of active TB in each group of patients as the end point. In view of the high cost of CT scanning, particularly in a screening environment, such trials should include assessment of cost effectiveness. Risks associated with increased exposure to radiation will also have to be taken into account. At present, there is insufficient evidence to justify the inclusion of HRCT scanning in TB outbreak investigation.