Copyright © Lippincott Williams & Wilkins. Unauthorized reproduction of this article is prohibited.New and improved tuberculosis diagnostics: evidence, policy,practice, and impactMadhukar Pai a , Jessica Minion a , Karen Steingart b and Andrew Ramsay cIntroductionIn 2010, poor diagnosis remains a major obstacle to globaltuberculosis (TB) control. In most high-burden countries,TB is still diagnosed using tools such as direct sputummicroscopy and chest radiographs. Fortunately, the pastfew years have seen an unprecedented level of interest,fundingsupport, andactivityfocused onthedevelopmentof new tools for TB diagnosis, and the new diagnosticspipeline for TB is rapidly expanding. In parallel, therehave been several new policy recommendations on TBdiagnostics by the WHO. Because recent publications[1 ? ,2,3 ? ,4]haveexhaustivelyreviewedthecurrentpipelineof new diagnostics and the expanding evidence base fortheir use, we focus our attention on how evidence istranslated into policy, limitations of the existing evidencebase, deficiencies in the current diagnostics pipeline, andchallenges involved in translating policies into practiceand impact.What is the evidence base for tuberculosisdiagnostics?The evidence base for TB diagnostics is ultimatelyderived from a large body of original research. Becauseindividual studies are seldom sufficient to inform policyand guideline development, the totality of availableevidence must be synthesized. Thus, systematic reviewsand meta-analyses are often necessary to summarize theevidence on a given diagnostic test. In the past decade,there have been over 35 systematic reviews published onTB diagnostics, on topics ranging from smear microscopyto molecular diagnostics and in-vitro assays for latent TBinfection (LTBI). All of these systematic reviews havebeen made available on a new website ‘Evidence-basedTuberculosis Diagnosis’ (www.tbevidence.org) compiledby the Stop TB Partnership’s New Diagnostics WorkingGroup, in collaboration with several agencies [5 ? ]. Whilethe key findings of published systematic reviews andmeta-analyses on TB diagnostics have been reviewedelsewhere [6 ? ], Table 1 provides a brief overview of theevidence base for TB diagnosis, essentially synthesizingthe evidence from several systematic reviews [7–37].What is lacking in current evidence base?Althougha large number ofsystematic reviewshavebeenpublished on TB diagnostics, almost all focus on testaccuracy (i.e. sensitivity and specificity). This is in parta Department of Epidemiology, Biostatistics andOccupational Health, McGill University, Montreal,Canada,b Francis J. Curry National TuberculosisCenter, University of California, San Francisco,California, USA andc UNICEF/UNDP/World Bank/WHO Special Programme for Research and Training inTropical Diseases (TDR), World Health Organization,Geneva, SwitzerlandCorrespondence to Madhukar Pai, MD, PhD, AssistantProfessor, Department of Epidemiology, Biostatisticsand Occupational Health, McGill University, 1020 PineAvenue West, Montreal, QC H3A 1A2, CanadaTel: +1 514 398 5422; fax: +1 514 398 4503;e-mail: madhukar.pai@mcgill.caCurrent Opinion in Pulmonary Medicine 2010,16:271–284Purpose of reviewThe aim is to summarize the evidence base for tuberculosis (TB) diagnostics, reviewrecent policies on TB diagnostics, and discuss issues such as how evidence istranslated into policy, limitations of the existing evidence base, and challenges involvedin translating policies into impact.Recent findingsCase detection continues to be a major obstacle to global TB control. Fortunately,due to an unprecedented level of interest, funding, and activity, the new diagnosticspipeline for TB has rapidly expanded. There have been several new policies andguidelines on TB diagnostics. However, there are major gaps in the existing pipeline(e.g. lack of a point-of-care test) and the evidence base is predominantly made up ofresearch studies of test accuracy.SummaryWith the availability of new diagnostics and supporting policies, the next major stepis translation of policy into practice. The impact of new tests will depend largely on theextent of their introduction and acceptance into the global public sector. This willitself depend in part on policy decisions by international technical agencies and nationalTB programs. With the engagement of all key stakeholders, we will need to translateevidence-based policies into epidemiological and public health impact.Keywordsdiagnostics, evidence, impact, policy, tuberculosisCurr Opin Pulm Med 16:271–284? 2010 Wolters Kluwer Health | Lippincott Williams & Wilkins1070-52871070-5287 ? 2010 Wolters Kluwer Health | Lippincott Williams & Wilkins DOI:10.1097/MCP.0b013e328338094f
