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Existing high-priority target product profiles (TPPs) of the World Health Organization (WHO) establish important needs for tuberculosis (TB) diagnostic development. Building on this earlier work, this guidance series aims to provide study guidance for performing accuracy studies of novel diagnostic products that may meet the 4 high-priority WHO TPPs and thus enable adequate evidence generation to inform a WHO evidence review process. Diagnostic accuracy studies represent a fundamental step in the validation of all tests. Unfortunately, such studies often have limitations in design, execution, and reporting, leading to low certainty of the evidence about true test performance, which can delay or impede policy and scale-up decisions. This introductory paper outlines the following: (1) the purpose of this series of papers on study guidance; (2) WHO evidence needs and process for the development of policy guidelines for new TB diagnostic tests; and (3) study design considerations, ie, general diagnostic study considerations, intended use of test and role in the clinical pathway, choice of population and setting, index-test specific issues, suitable reference standard and comparators, study flow and specimen issues, and finally key issues beyond accuracy that should be considered. The other 4 papers in this series will provide more detailed guidance for each of the 4 WHO high-priority TPPs. By increasing the clarity around the clinical evaluation needs for tests that have the potential to meet the TPP specifications, we hope to support harmonized evidence generation and enable the WHO review process towards meeting the WHO End TB Strategy targets for reducing the incidence and mortality associated with TB. [ABSTRACT FROM AUTHOR]

The development and implementation of rapid molecular diagnostics for tuberculosis (TB) drug-susceptibility testing is critical to inform treatment of patients and to prevent the emergence and spread of resistance. Optimal trial planning for existing tests and those in development will be critical to rapidly gather the evidence necessary to inform World Health Organization review and to support potential policy recommendations. The evidence necessary includes an assessment of the performance for TB and resistance detection as well as an assessment of the operational characteristics of these platforms. The performance assessment should include analytical studies to confirm the limit of detection and assay ability to detect mutations conferring resistance across globally representative strains. The analytical evaluation is typically followed by multisite clinical evaluation studies to confirm diagnostic performance in sites and populations of intended use. This paper summarizes the considerations for the design of these analytical and clinical studies. [ABSTRACT FROM AUTHOR]

Patient-centered care is a central pillar of the World Health Organization’s End TB Strategy. Understanding where patients access health services is a first step to planning for the placement of services to meet patient needs and preferences. The patient-pathway analysis (PPA) methodology detailed in this article was developed to better understand the alignment between patient care seeking and tuberculosis service availability. A PPA describes the steps that people with tuberculosis take from the initial care visit to cure. The results of a PPA reveal programmatic gaps in care seeking, diagnosis, treatment initiation, and continuity of care. They can be used as inputs to an evidence-based process of identifying and developing interventions to address the gaps in patient care. This paper summarizes the steps to conduct a PPA and serves as the basis for understanding country case studies that profile the use of PPA. [ABSTRACT FROM AUTHOR]

An editorial is presented on the use of sputum microscopy for the analysis if mycobacterium tuberculosis infections, focusing on the paper by Datta and colleagues within the issue of "The Journal of Infectious Diseases," on mycobacterial counts. It demonstrates that close contacts of patients with higher percentage of fluorescein diacetate microscopy-negative cells are significantly at risk of developing tuberculosis.