Blood tests for TB widely used in India not accurate
Washington: A new study has revealed that commercial blood serum antibody tests—widely used in India and other developing countries to diagnose active tuberculosis—are not accurate or cost-effective.
Researchers at the Johns Hopkins Bloomberg School of Public Health, the University of Washington School of Public Health and McGill University found use of serological tests in India resulted in more DALYs (years of healthy life lost to premature death and illness), more secondary infections, and more false-positive diagnoses of TB, compared to the use of microscopic sputum smear analysis or culture.
The findings recently led the World Health Organization to recommend against the use of commercial serology tests in the diagnosis of active TB.
“Microscopic analysis of sputum for TB is cheap and widely available, but misses half of all TB cases,” said David Dowdy, MD PhD, assistant professor in the Department of Epidemiology at the Bloomberg School of Public Health and lead author of the study.
“Serological tests are simpler and faster than culture, and are also commercially available in India, so they are an attractive option in theory.
“However, we found that they are not accurate enough to be useful—after accounting for missed and false-positive TB diagnoses, serological tests cost more and delivered less than either microscopy or culture. Quite simply, serological tests should not be used to diagnose active TB,” he stated.
The study has been published in the August 9, 2011 edition of PLoS Medicine.