Evidence-Based Tuberculosis Diagnosis

T here is great excitement in the tuberculosis (TB) scientific community over the introduction of new tools into TB control activities. The development of new tools is an important component of the Global Plan to Stop TB and the World Health Organization's new global Stop TB Strategy [1,2]. Anticipating the introduction of new tools, the Stop TB Partnership has established a Retooling Task Force to develop a framework for engaging policy makers to foster accelerated adoption and implementation of new tools into TB control programs [3]. While new tools offer great promise in clinical medicine and in public health, limited resources and the movement toward evidence-based guidelines and policies require careful validation of new tools prior to their introduction for routine use. The world spends an estimated US$1 billion per year on diagnostics for TB [4]. It is important to ensure that such expenditure is backed by strong evidence. Ideally, clinical and policy decisions must be guided by the totality of evidence on a given topic. This is particularly 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 [5]. These concerns are being taken seriously [6,7], and the outcome should be evident in upcoming TB guidelines and policies. In fact, the World Health Organization (WHO) recently announced its approach for developing new policies on TB in a document entitled " Moving Research Findings into New WHO Policies " [7]. According to this document, in order to consider a global policy change, WHO must have solid evidence, including clinical trials or field evaluations in high TB prevalence settings. The steps involved in the policy process include a comprehensive review of the evidence, as well as expert opinion and judgment (Box 1). 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. While primary diagnostic trials are needed to generate data on test accuracy and operational performance, systematic reviews provide the best synthesis of current evidence on any given diagnostic test [8]. Although a large number of trials on TB diagnostics have been published, surprisingly, no systematic reviews were published until recently. In the past few years, at least 30 systematic reviews and meta-analyses have been published on various TB tests [9–38]. These reviews have synthesized the results of …