Tuberculosis Epidemiologic Studies Consortium (TBESC)

Task Order 5: Prevalence of LTBI among high-risk populations in the United States

Task Order 5 examines the prevalence of latent tuberculosis infection (LTBI) among high-risk populations and compares a new diagnostic test for TB infection (QuantiFERON^®-TB In-Tube) with the tuberculin skin test (TST). It includes homeless persons in Seattle/King County, WA, new refugees and HIV+ persons in Dekalb County, GA, and alcohol and substance abusers (ASA) in North Carolina.

Sites

Emory University (Atlanta, GA), Seattle and King County Public Health Prevention – TB Control Program, and RTI International (Triangle Park, NC)

Study Objectives

1. Estimate the prevalence of LTBI in four high-risk populations (homeless in Seattle/King County, HIV-infected persons in Dekalb County, GA, newly arrived refugees in Dekalb County, GA, and substance abuse population in Granville County, NC).
2. Evaluate the test characteristics (sensitivity/specificity) and compare the field performance of TST with the T-SPOT (only in the HIV-infected population) and Quantiferon Gold In-Tube test (QFT-GIT).

Study Design

This is a cross-sectional study that involves testing a representative sample of eligible subjects for LTBI using the purified protein derivative (PPD) tuberculin skin test (TST) and the QFT-GIT test and administering a brief questionnaire on socio-demographic characteristics and previous LTBI and TB history to each participating subject. The percentage of LTBI patients who receive and complete treatment for LTBI will also be assessed.

Study Progress

All sites (Seattle, RTI, and Emory) have completed enrollment: Homeless in Seattle/King County, n=222; RTI/Substance abuse participants, n=510; Newly arrived refugees/Dekalb County, GA, n=608; Emory/HIV+ population/Dekalb County GA, n=608 (QFT-GIT), n=338 (t-spot). Preliminary results have been presented at a number of conferences. A manuscript from the final results is being prepared. The key finding is that QFT-GIT found fewer positives compared to the TST among refugees for whom TST generally has poor specificity. QFT found more positives among HIV+ persons and Alcohol/Substance abusers for whom TST may have poor sensitivity.

Last Modified: 07/25/2007

Last Reviewed: 05/18/2008
Content Source: Division of Tuberculosis Elimination
National Center for HIV/AIDS, Viral Hepatitis, STD, and TB Prevention

 
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