Drink deep, or taste not the Pierian spring: Inadequate use of GeneXpert-Xpert MTB/RIF- and impact on the NTP tuberculosis case notifications in Africa

Over the past five years, the diagnosis of tuberculosis (TB) has changed from simple to 'complicated': from a simple (age-old) sputum smear microscopy (with or without a chest X-ray) to a modern molecular test (Xpert MTB/RIF) which is more sensitive to detect TB than sputum microscopy. However, the molecular test is 'expensive' to implement in the public health settings, and cannot be adequately implemented without the support of international donor agencies, in the resource limited country settings. Thus, several countries  are implementing the technology in a piecemeal approach- called roll-out strategy- starting from the target groups such as multi-drug resistant TB, TB among HIV clients, cross-border populations, refugees and other vulnerable populations to general population if adequate capacity is 'acquired'. 'Saturation' of GeneXpert technology has never been more than 25%-35% in several TB high burden countries, and further the 'optimal' theoretical capacity of GeneXpert systems to run about 2000 tests in a year was never realized in clinical settings due to various reasons. Out of this operational reality, countries have endorsed use of Xpert MTB/Rif test along with sputum smear microscopy, simultaneously, based on the on-site availability. World Health Organization, too, endorsed such a step (with ever multiplying diagnostic tests and the 'algorithms'- latest was additional Urinary LAM test among certain HIV positive patients) For example, at the health facilities where GeneXpert systems were installed (generally at the level of hospitals, and district level health centers) Xpert MTB/RIF test is the initial test for diagnosis of tuberculosis. And in the absence of GeneXpert systems, sputum smear microscopy remained the initial test for diagnosis of TB. Further, referral to GeneXpert testing from microscopy sites became a catch word, although specimen transport systems were never invested upon and were not well developed. This lead to diagnostic delays, and the clinicians could not adjust. This reality made the NTPs endorse two types of diagnostics technologies for initial TB diagnosis at two levels of health care- based on availability-within a country set-up (either Xpert MTB/RIF test or Smear microscopy). Smear negative 'clinical' TB (TB that could not diagnosed by sputum microscopy due to low sensitivity of microscopy, but clinically evident) became unpopular with introduction of Gene"Xpert". Clinicians were discouraged to make judgement in the absence of Gene'Xpert' results or microscopy results. This limitation is further amplified in the high HIV burden countries, due to differential clinical picture TB patients present with. The National TB programmes (NTPs) failed reorient their clinical staff (at the same pace as technologies are changing). In practice, the clinicians (being aware of HIV/AIDS and un-symptomatic TB among HIV clients) diagnosed 'clinical TB' (TB without bacteriological confirmation) among HIV positive clients, but disregard the clinical symptoms of TB among HIV negative clients. How this type of anomaly could be identified: (1) shift in proportion of smear negative TB to smear positive TB, in the historical case notifications (2) discussion with clinicians at the smear microscopy sites (3) 'missed-to-diagnose' TB cases being high among HIV negative TB clients (4) virtually no impact of GeneXpert based diagnosis on the NTP case notifications.

What are the consequences of this piecemeal implementation of modern TB diagnostics: Continued transmission of TB among communities, and long term wastage of resources. The global END-TB goals, indicators and targets will not be met any time, sooner. Solution: Either invest more on modern diagnostics, or revamp the public health systems with break-neck speed of changing diagnostic realities.

The above observations emphasize that roll-out should be aimed at replacing the existing technology- not a piece meal approach. It justifies common adage: Drink deep, or taste not the Pierian spring.
-Ajay (notes from Uganda)