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Researchers Create Scoring System to Predict TB Risk in Adults

When it comes to screening for tuberculosis (TB), current World Health Organization (WHO) guidelines are clear: for index cases of pulmonary TB, all household contacts should be investigated via screening and surveillance.

Unfortunately, in practice, these recommendations are often easier said than done, particularly in the resource-poor areas in which TB is prevalent. However, the authors of a study published on August 18, 2017 in the journal Lancet Infectious Diseases, believe they have developed a tool to make this process easier—and affordable—for clinicians in these high-risk communities: a scoring system designed to predict 10-year TB risk in adult contacts of index cases. The research project received funding from a number of important sources in the TB world, including the Wellcome Trust, the Bill & Melinda Gates Foundation, the World Health Organization (WHO), and TB REACH.

“In the majority of resource-constrained settings where much of the world's TB occurs, management of contacts is given low priority because TB programs are focused on diagnosing and managing patients with TB. [These countries] have few resources allocated to TB prevention, particularly among adult contacts who are often ineligible for preventive treatment,” study co-authors Matthew J. Saunders, MBChB, and Carlton A. Evans, FRCP, both of Imperial College, London, said in an email to Contagion®. “Furthermore, contacts often have to follow a long road from being identified to complete screening, and ultimately, to be prescribed preventive therapy… completing a variety of tests to exclude active TB, frequently including a tuberculin skin test, and attending multiple appointments at clinics that are difficult to access and associated with direct and indirect costs.”

However, Saunders and Evans believe their scoring tool has the potential to simplify this process. From 2002 to 2006, they and their colleagues enrolled 2,017 household contacts (15 years of age and older) of 715 index cases with pulmonary TB who lived in shanty towns in Ventanilla, Peru, and they followed the contacts for more than a decade (median follow-up 10.7 years), until February 2016. Of the 2,017 contacts, 178 (9%) developed TB during 19,147 person-years of follow-up.

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