Updated on 30 July 2012
Our approach to immunodiagnostics cannot be mathematical in terms of percentage sensitivity and specificity but needs to be pragmatic to make it useful to the clinicians in diagnosis, monitoring and management of patients for continued patronage. Another reason for failure of serology is the expectation that it should be similar to sputum smear or culture, the gold standard, in spite of associated limitations. We must understand that serological tests cannot replace the culture and sputum smear microscopy but can certainly be proved the valuable adjunct in clinical decision making wherein we face the clinician with his or her clinical judgment, adding to the complexity of diagnosis.
Need regulatory support and task force
Despite increasing emphasis on strengthening infrastructure for healthcare, the Indian government has overlooked the need to chalk out a well defined regulatory pathway for diagnostic products, leaving many domestic industries lurching in the dark. The Indian diagnostics market witnessed a growth of 22 percent from 2,000 crore to 2,440 crore in 2010-11. Despite the prime significance of this sector, a well-defined regulatory pathway for diagnostic products is awaited. We understand that the independent validation of a diagnostic kit is an important process as an in-house team can sometimes be biased. However, there is no clear pathway described by the government on what-and-how exactly should the validation process be carried out.
Companies and research organizations have to scout around for institutes or hospitals to test and validate their tools. Without strong support of the WHO, FIND, other organizations and regulatory task force, the vision 2020 to eliminate TB looks gloomy. Instead of imposing harsh decisions like banning the tests, international organizations must empower the national implementation program to undertake such diagnostic kits for proper validation studies. We desperately need the tests that use a cocktail of antigens to cover the entire spectrum of tuberculosis for diagnosis irrespective of the HIV status, owing large genetic diversity among Indian population.
Possible measures for bringing TB tests into market
Regulation of in vitro diagnostics (IVDs) is weak in India. The central Drug Standard Control Organization (CDSCO) classified IVDs as "critical" or "non-critical" with only a few test like HIV, Hepatitis B &C being considered "critical". TB tests are not classified as "critical tests" by the DCGI, and this allows the entry of sale of suboptimal sero-diagnostics without proper validation. Quality council of India, which is an autonomous body of Department of Industrial Policy and Promotion, Government of India, must address this by establishing and improving national accreditation structures, including National Accreditation Board for Testing and Calibration Laboratories (NABL), and National Accreditation Board for hospital and Healthcare Providers (NABH).
Creation of an "Indian Standards for TB Care" along the lines of the "International Standard for TB Care" for both public and private sectors might help in overcoming the reluctance about accepting the current ELISA-based leads for diagnosing TB, following complete validation of test kit. Owing to the large genetic diversity in the country, importing and usage of foreign kits by the doctors would again prove dangerous leading to mismanagement of TB. A significant contribution by India in the field of in-house PCR assays and cost effective immunodiagnostic serological kits with better sensitivity and specificity; judicial use of cocktail antigens to detect antibody along side of antigen; and immune complex antigen detection would help in developing a successful immunodiagnostic profile for tuberculosis.