Blood-based antibody detection tests for tuberculosis (TB) have come under the spotlight in a research article published in PLoS Medicine. The authors, based in North America and Europe, conducted a "systematic review and meta-analysis" of studies that have been conducted on the accuracy of the tests, and have concluded that they do not perform well in comparison to standard methods. Many of the studies have been poorly conducted, and there is a lack of information on how the tests perform with children and people who are infected with HIV.
The standard test for TB (the sputum-smear test) has limitations. It is not particularly good at identifying active TB disease in children or people who are HIV-positive. It is also not very sensitive; in other words many people who have active TB disease may not give a positive reading. Therefore, there is an urgent need to develop and evaluate new tests. These tests would have to be cheap, as the countries with the highest rates of TB are in the developing world.
Many companies have developed tests intended to detect the presence of antibodies against TB in the patient's blood. These tests are now being strongly promoted for use in developing countries. However, the authors of the PLoS Medicine article have concluded that, "...published data on commercial antibody detection tests produce inconsistent estimates of accuracy, and none of the assays performs well enough to replace sputum-smear microscopy. These tests thus have little or no role to play in the diagnosis of pulmonary TB at the present time". (Efforts are under way to develop advanced versions of antibody and antigen detection tests, using new technologies. More research to evaluate these newer tests is needed.)
Citation: Steingart KR, Henry M, Laal S, Hopewell PC, Ramsay A, et al. (2007) Commercial serological antibody detection tests for the diagnosis of pulmonary tuberculosis: A systematic review. PLoS Med 4(6): e202. (http://medicine.plosjournals.org/perlserv/?request=get-document&doi=10.1371/journal.pmed.0040202)
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