Lancet World Report examines health risks associated with inaccurate TB tests, WHO's upcoming recommendations

With "scores of commercial serology tests for tuberculosis ... being sold in high-burden countries," the "WHO is due to release a negative policy recommendation - the first of its kind for the organisation" - after several reviews have "indicated poor performance of these tests," Lancet World Report writes in a piece that documents the health risks associated with a growing number of inaccurate TB tests. However, "manufacturers continue to claim that their tests are effective and fill a diagnostic niche, especially in sputum smear-negative patient groups," the journal notes.

"Everyone is aware of the consequences of bad drugs and vaccines, but nobody really thinks about bad diagnostics and what impact they can have," explained Madhukar Pai, co-chair of the STOP-TB Partnership's new diagnostics working group, according to the journal. In a report, released by the WHO Strategic and Technical Advisory Group for TB at the end of December, the group describes "'the adverse impact of misdiagnosis and wasted resources on patients and health services when using these tests for the diagnosis of active TB,' and recommends WHO to proceed with written guidance advising against current serodiagnostic kits," according to the article.

"Further targeted research is strongly recommended since potential exists for research to develop accurate serologic assays, which could fill the point-of-care niche," Lancet writes. However, as noted by Karin Weyer, WHO coordinator of TB diagnostics and laboratory strengthening, the WHO is working on how best to communicate the negative policy recommendations "so as not to stifle innovation and research investment in tuberculosis diagnostics," according to the journal. Although commercial serodiagnostic kits are available worldwide, the kits are a particular problem in India, "where Pai estimates that serodiagnostic kits are used on at least 1.5 million people with suspected tuberculosis every year," Lancet writes.

The piece describes how the financial incentives for physicians have contributed to the use of such tests and examines how the anticipated WHO guidance on TB tests may impact their sale and use in the private sector, and what this will mean for collaborations between the public and private sector, or public-private mix (PPM), which "is being hailed in some quarters as the key to increasing efforts to tackle tuberculosis." The article includes comments by Sanjeev Chaudhry, chief executive of what the journal describes as "a large private Indian diagnostic laboratory chain," and Camilla Rodrigues, a physician at Hinduja Hospital, in Mumbai, India, who describe several ways to stem the use of such tests (Morris, 1/8).