Chest radiography validity in screening pulmonary tuberculosis in immigrants from a high-burden country

Abstract

Background: Chest x-ray (CXR) is widely used for diagnosing and screening pulmonary tuberculosis (PTB), yet its validity is debatable and its costs are relatively high. This study aimed to determine the validity of CXR screening in detecting radiological findings compatible with active PTB or with old healed tuberculosis (OHTB).

Methods: All Ethiopian immigrants to Israel between 2001 and 2005 were radiographed before emigration. Immigrants whose CXR demonstrated PTB or OHTB were evaluated, treated, and followed for one year after arrival. The end point of this historical cohort study was a diagnosis of active pulmonary disease within the study period.

Results: CXR was performed on 13,379 immigrants. Changes suggesting PTB were identified in 150 (1.1%) of those, and 46 were diagnosed with active PTB. Sensitivity, specificity, and positive predictive value of a CXR suggesting PTB were 80.1%, 99.2%, and 31%, respectively. As PTB prevalence in this cohort is 0.4%, post-test odds for CXR suggestive of PTB were 75.5. Changes suggesting OHTB were identified in 257 (1.9%) immigrants. Of those, 15 (5.8%) developed active PTB within one year following arrival. Sensitivity, specificity, and positive predictive value of CXR suggestive of OHTB were 17.2%, 98.2%, and 5.8%, respectively, when active PTB during the first year was the end point. In this study, 291 CXR were required to detect one active PTB patient, costing $5,802.

Conclusions: CXR is a valid and cost-saving tool for screening active PTB in immigrants originating in high-burden countries, and is beneficial in detecting OHTB in immigrants who are at a higher risk for developing active PTB.