Comprehensive new resource for evidence-based TB diagnosis.

There is palpable excitement in the TB scientific community over the introduction of new tools (diagnostics, drugs and vaccines) into TB control activities. The development and evaluation of new tools is an important component of the ‘Global Plan to Stop TB’, the WHO’s new global ‘Stop TB Strategy’, and the Stop TB Partnership’s (STP’s) Research Movement [1,2]. While innovation and new tool development are critical for clinical medicine and public health, limited resources and the movement toward evidence-based practice guidelines require careful validation of new tools and approaches prior to their widespread routine use. According to one estimate, the world spends US$1 billion each year on diagnostics for TB [3]. Such expenditure must be justified by strong evidence. Ideally, clinical and policy decisions must be guided by the totality of evidence on a given test or intervention. This is highly relevant for TB, where concerns have been raised about the lack of emphasis on evidence of effectiveness in some of the existing TB guidelines and policies [4]. High-quality evidence on TB diagnostics is critical for the development of evidence-based policies on TB diagnosis and, ultimately, for effective control of the global TB epidemic [5,6]. While primary diagnostic trials are needed to generate data on test accuracy (e.g., sensitivity and specificity) and performance and impact in field conditions, systematic reviews provide the best synthesis of current evidence on any given diagnostic test [7]. However, systematic reviews of test accuracy, while necessary, are not sufficient for policy and guideline development. Test accuracy data must be considered along with impact of the test on patient-important outcomes, and other factors including quality of the evidence, the uncertainty about values and preferences associated with the tests and presumed patient-important outcomes, and cost and feasibility, especially in resource-limited settings [8].