Feasibility of Decentralised Deployment of Xpert MTB/RIF Test at Lower Level of Health System in India

Abstract

BackgroundXpert MTB/RIF is an automated cartridge-based nucleic acid amplification test that has demonstrated its potential to detect tuberculosis and rifampicin resistance with high accuracy. To assist scale-up decisions in India, a feasibility assessment of Xpert MTB/RIF implementation was conducted within microscopy centres of 18 RNTCP TB units.MethodsAs part of programme-based demonstration of Xpert MTB/RIF implementation, we recorded and analysed association between key implementation factors and the ability of test to produce valid results. Factors contributing to test failures were analysed from GeneXpert software data which provides ‘failure codes’ and causes for test failures.ResultsFrom March’12 to January’13, total 40,035 suspects were tested by Xpert MTB/RIF, and 39,680 (99.1%) received valid results (Cumulative: 37157 (92.8%) on first attempt, 39410 (98.4%) on second attempt, 39637 (99.0%) on third attempt and 39680 (99.1%) on more attempts). Overall initial test failure was 2,878 (7.2% (4%–17%)); of these, 2,594 (90.1%) were re-tested and produced valid results. Most frequent reason of test failure was inadequate sample processing or equipment malfunction (3.9%). Other reasons included power failure (1.1%), cartridge integrity/component failure (0.8%), device-computer communication error (0.5%), and temperature-related errors (0.08%). Significant variation was observed in failure rates both across instruments and over time; furthermore, substantial variation was observed in failure rate in two cartridges lots.ConclusionInstallation required minimal infrastructure modifications and concerns about adequacy of human resources under public sector facilities and temperature extremes proved unfounded. Under routine conditions, Xpert MTB/RIF provided 99.1% valid results in TB suspects with low overall failure rates (7.2% initial failure, 0.9% final failure); devices provided valuable real-time feedback on reasons for test failure, which were used for rapid corrective action. High modular replacement (32%) and inter-lot cartridge performance variation remain sources of concern, and warrant close monitoring of failure rates as a key quality indicator.

Unsuccessful Xpert® MTB/RIF results: the Nigerian experience

“…[9][10][11] The WHO recommended country-specific operational research, as diagnostic tests that perform well in controlled settings may not always perform optimally in the settings where they are to be used. 12 We studied the rate, distribution and causes of unsuccessful Xpert test outcomes, with the aim of identifying key areas that need to be strengthened for optimal performance of the assay.…”

“…Raizada et al reported that most temperature-associated errors were related to clogging of exhaust fan filters by dust or the inappropriate positioning of equipment. 12 It is therefore recommended that Xpert operators, especially those in the Northern region, routinely clean the filters, monitor and chart ambient room temperature, and check the machine's internal temperature whenever a Category A error is flagged. This confirms the source of the error and facilitates fast and accurate troubleshooting.…”

Connectivity of diagnostic technologies: improving surveillance and accelerating tuberculosis elimination

“…Self-contained molecular diagnostic devices have been successfully deployed to detect tuberculosis (TB) (e.g., Xpert w MTB/RIF; Cepheid, Sunnyvale, CA, USA 1 ) or monitor treatment for the human immunodeficiency virus (HIV) (e.g., Alere Pimae CD4, Alere, Waltham, MA, USA 2 ) in very basic clinical facilities. Despite the accumulating evidence that these tools can be successfully used in the most challenging environments 3,4 and the establishment of distribution and funding channels that should theoretically allow any country to access and scale up these new technologies, the majority of patients that could benefit from these technical evolutions still do not have access to them. It is clear that the introduction of an improved TB diagnostic tool is not sufficient to assure improved outcomes for patients, as the details of implementation within existing health delivery systems have a critical influence on impact.…”

GeneXpert: a game changer in the detection and diagnosis of childhood tuberculosis

“…Raizada N et al analysed the implementation of this technique in 18 centres in India and assessed the reasons for failure as processing errors and equipment malfunction, electricity related issues, issues due to non maintanence of accurate temperature, cartridge related issues which required attention. 34 Hence, one should not forget the ageold tested methods, though yield is delayed and less, till more roles of this assay is established. There is no doubt that this assay has revolutionised the early and rapid detection of tuberculosis particularly in countries burdened with the disease and struggling to fight it.…”