ABSTRACT
The diagnosis of active tuberculosis is, and will always be, a clinical exercise. No single diagnostic test for tuberculosis exists that can be performed rapidly, simply, inexpensively, and accurately as a stand-alone test. In resource-limited countries, heavy dependence on the rapid but inaccurate acid-fast bacille (AFB) smear can lead to the consequence of underdiagnosis of tuberculosis. In affluent countries, the availability of a variety of conventional methods (e.g., chest radiographs, smear and culture examinations) may result overall in overdiagnosis of tuberculosis (1). Recently, approval of rapid andmore accurate nucleic acid amplification (NAA) assays by the U.S. Food and Drug Administration (FDA) promises improvement in the rapid diagnosis of tuberculosis, but the cost of implementing this technology currently limits widespread use. Another technology, immune-based serologic assays, can be performed rapidly, simply, and inexpensively; however, low diagnostic accuracy
has been a limitation. Because of the limitations of laboratory-based diagnostic methods, assessment of clinical suspicion of tuberculosis (CSTB) remains the cornerstone of tuberculosis diagnosis. Suspicion of tuberculosis drives the initiation and scope of diagnostic inquiries, and the suspicion of active tuberculosis drives the decision to treat. The influence of clinical suspicion varies in degree from great impact when reliability of a test is low to minimal impact when reliability is high, but it always plays some role in the diagnostic process.
