%0 Journal Article
%T Interferon-Gamma Release Assays versus Tuberculin Skin Testing for the Diagnosis of Latent Tuberculosis Infection: An Overview of the Evidence
%A A. Trajman
%A R. E. Steffen
%A D. Menzies
%J Pulmonary Medicine
%D 2013
%I Hindawi Publishing Corporation
%R 10.1155/2013/601737
%X A profusion of articles have been published on the accuracy and uses of interferon-gamma releasing assays. Here we review the clinical applications, advantages, and limitations of the tuberculin skin test and interferon-gamma release assays and provide an overview of the most recent systematic reviews conducted for different indications for the use of these tests. We conclude that both tests are accurate to detect latent tuberculosis, although interferon-gamma release assays have higher specificity than tuberculin skin testing in BCG-vaccinated populations, particularly if BCG is received after infancy. However, both tests perform poorly to predict risk for progression to active tuberculosis. Interferon-gamma release assays have significant limitations in serial testing because of spontaneous variability and lack of a validated definition of conversion and reversion, making it difficult for clinicians to interpret changes in category (conversions and reversions). So far, the most important clinical evidence, that is, that isoniazid preventive therapy reduces the risk for progression to disease, has been produced only in tuberculin skin test-positive individuals. 1. Introduction Tuberculosis (TB) is an important cause of morbidity and mortality worldwide [1]. Governmental and non-governmental organization efforts and investments in the last decades to control the epidemic have resulted in a steady decline in disease incidence and mortality [2]. One third of the world population, however, has latent tuberculosis (TB) infection (LTBI), and to reach the United Nations Millennium Goals of eliminating the disease by 2050, it is its necessary to couple diagnosis and treatment of active disease with new approaches to reduce this vast reservoir of LTBI, sufficient for generating new TB cases for many decades even if transmission was suppressed [3]. Thus, in addition to rapid, accurate, and inexpensive detection of active TB, the detection¡ªand treatment¡ªof LTBI is also an important strategy for TB control [1]. In the present paper, we summarize the advantages and limitations of tuberculin skin testing (TST) and overview the evidence for the use of the newer interferon-gamma release assays (IGRA) for the diagnosis of LTBI (Table 1). Table 1: Comparison of TST and IGRA regarding several tests' characteristics. 2. Tuberculin Skin Testing Until the beginning of this century, TST was the only diagnostic method for detecting LTBI. The test is based on a delayed-type hypersensitivity reaction that occurs when those infected with M. tuberculosis are exposed to certain
%U http://www.hindawi.com/journals/pm/2013/601737/