2 Recommendations

Leveraging the GeneXpert system for viral load testing

By Madhukar Pai Moderator | 15 Jul, 2017

Hi All

Although over 6500 GeneXpert machines are now available for TB testing in over 100 countries, these systems are often underused because of high cost, restrictive algorithms, inadequate decentralisation, exclusion of the private sector from concessional pricing, and weak implementation of policies.

One potential solution is to expand access to tuberculosis testing, while simultaneously using the GeneXpert platform to test for other diseases of global health importance. Given the high co-prevalence of TB and HIV in many settings, and the need for greater integration of tuberculosis and HIV services, it makes sense to use the GeneXpert technology for HIV viral load testing. The new global 90-90-90 targets for HIV/AIDS require scaled-up HIV-1 viral load testing.

Please see the attached study from Manipal University, India, where the GX system, already in use for TB, was leveraged for HIV VL testing. The data show that the results of the Xpert HIV-1 Viral Load assay correlated highly with the current reference standard and therefore could be considered for wider use in India by using the large installed base of GeneXpert systems in the TB programme. However, subsidised pricing, similar to that of the Xpert MTB/RIF cartridge, will be essential for scaled-up use in India and other LMICs.

Free access: http://www.sciencedirect.com/science/article/pii/S2214109X17302474

Best

Madhu

Replies

 

Steven Badman Replied at 12:14 AM, 16 Jul 2017

Great to see another paper validating Xpert HIV VL and the device being leveraged or use with other assays.
We are trialing Xpert Qual for the Early infant Diagnosis (EID) of HIV for use along similar lines and in an effort to reduce ART treatment delays and close the IVD and treatment loop with HIV 09-90-90 end points in mind.
As discussed at the recent McGill GHDx workshop, it would be ideal to access under-utilised Xpert platforms although I am not sure how willing others may be to "share" given they are often owned by different parties.
Even so, we are keen to see this happen so that other key assays, including those for HPV and (CT-NG, TV) STIs, can also be run on a shared platform and especially Xpert devices are close to antenatal clinics.

Perhaps we need to develop a user pays - booking app for this Madhu.

RAJESH SOOD Replied at 12:24 AM, 16 Jul 2017

Sir

The Gene Xpert machines in India are the 4 cartridge ones, and the load it
can take is 12 tests per day.

With the level of penetration, the need to test all sputum negative and
chest x ray positive as per new diagnostic algorithm, there is huge
shortage of CBNAAT capacity.

It may not be possible in present setup to use these existing machine for
other disease diagnosis.

However GeneXpert machines available in ART centres can definitely be used
for the addl testing of viral load etc. and will be useful add on facility
near to the patient.

Prof Sarman Singh Replied at 12:36 AM, 16 Jul 2017

Dear Madhu, we have also evaluated Xpert for HIV viral load and also for
HCV viral load. Results are excellent, but the issue is that not many HIV
patients in India and Africa are followed on the basis of viral load. Even
the CD4 is not done so regularly. What to think of viral load based follow
up. Leveraging is one thing but money for health expenditure is real issue.
Prof. Sarman Singh, New Delhi

Sylvester Moyo Replied at 12:40 AM, 16 Jul 2017

Dear All,

That's a very great question by Steven, the ownership by different parties is one important consideration.

Another question that I had is what platforms are already in-country for VL testing in India (or any other country that is currently embarking on using the GeneXpert VL testing) and how do the efforts of trying to improve both GeneXpert device utilisation and access to diagnostics affect such things as reagent rental agreements of these VL platforms or if its an outrightly purchased VL platform how do the efforts to increase utilisation of the GeneXpert then affect utilisation of the VL platforms? How is this balanced?

I can understand for countries who already do not have accessible VL platforms (i.e. where VL testing is centralised) but what about countries who have better access to VL testing platforms? If anyone can share their experiences that would be great to learn.

In the country that I am working in there is often a challenge with getting a second VL done after the 1st detectable viral load result and as there is 20% unsupression rates the number of repeat VL tests (2nd VL) after stepped up adherence counselling are small enough to consider doing on the GeneXpert machines without affecting TB diagnostic testing.

Additionally, on the cost aspects, in LMIC where funding is a challenge that needs careful consideration, how do you come up with a percentage to forecast the GeneXpert VL cartridges vs Conventional testing that you will need to procure e.g. in my scenario I would think to convert 10% of funds available for Conventional VL testing reagents towards GeneXpert VL cartridges for a start as a pilot to monitor consumption rates to inform future procurement and also for sustainability as funding to get the GeneXpert VL cartridges is not always guaranteed where conventional VL platforms already exist.

Trying to learn from other countries/colleagues who have considered this part to also learn how they went about it.

Regards
Sylvester Moyo

ABEBE MEGERSO ADLO Replied at 1:13 AM, 16 Jul 2017

Hi! Madhukar;

Thank you so much for your post on utilization of the Gene Xpert. Under
utilization is themain problem in our country, Ethiopia, too.
Here, the main problem leading to the under utilization is restrictive
algorthm. Researchers are urging the Minstry of health to revise the
algorthm so that the scarce machines will be adequately utilized.

Elham Elhshik Replied at 2:02 AM, 16 Jul 2017

Thank you all for opening up such a discussions. In Libya the prooblem is different. I work in Tripoli in what supposed to be a tertiary center, caring for HIV and dealing with many cases of TB and many others with suspected MDR-TB. With my colleagues we have been eagerly looking to use the GeneXpert but so far we failed to get one for use.

It would be of great benefit for both EID and TB.

Sunday Chinenye Replied at 2:08 AM, 16 Jul 2017

The experience from LMICs especially in Africa where I have had
opportunities to work in several scenarios, shows that the key issues
remain lack of political will and country ownership. In virtually all
African countries GeneXpert technology service is still donor-driven and
donor-dependent and this cannot ensure sustainability in the absence of
country ownership. The World Health should consider this a priority issue
to handle.

Steven Badman Replied at 2:59 AM, 16 Jul 2017

I also understand that the manufacturer is currently seeking WHO pre-qualification for the Xpert HIV VL assay and wonder if this might lead to global LMIC pricing similar to that of Xpert TB. I hope so as this would;
(a) enhance the opportunity for triangulated molecular testing at the point of care (HIV Qual, including EID + VL + TB).
(b) and perhaps help reduce the cost of follow up VL testing, and enhance suppression rates, once ART has been established.

Emmanuel Fajardo Replied at 10:40 AM, 16 Jul 2017

I don't think having the Xpert HIV VL WHO prequalified per se will lead to global LMIC pricing similar to that of Xpert TB, we need to explore different pricing reduction strategies but an important and immediate one is the option to bundle TB volumes with virological tests.

Currently, the HBDC virology pricing from Cepeheid is based on a tiered and volume-based pricing model, so at the moment the only way to get to a reduced price close to that of the Xpert MTB/RIF assay is by scaling-up the use of virological tests. However, as mentioned in the Nash and colleagues paper and recently in the MSF Out of Step Report, countries are still struggling to implement universal Xpert MTB/RIF testing due to several reasons, but among them, current pricing still stands as an important barrier.

Price/test Ceiling price 500K tests/year 1M tests/years 1.5M tests/year 3M tests/year 4M tests/year
HIV-1 VL 16,80 16,08 15,30 14,75 13,10 11,98
HIV-1 Qual 17,95 17,43 16,65 16,08 14,45 13,35
HCV VL 17,10 16,43 15,65 15,16 13,45 12,45
HPV 16,70 15,40 15,15 14,45 12,40 11,35

Although the above virological tests can be aggregated together for volume, the Xpert MTB/RIF test cannot be aggregated, therefore, it will take much longer to reach breakpoint volumes. I think we - as a global community - should engage with Cepheid to discuss the possibility to allow TB cartridges to be pooled with virological tests, otherwise countries will face hurdles to implement and scale-up the use of the tests on the ground!

We are aware that the Xpert MTB/RIF assay follows a different production line compared to the virological assays but I don't understand how this prevents bundling TB volumes with other virological tests; in fact, other manufacturers of lab-based platforms already offer this alternative, so it would be great to hear Cepheid's perspective about this particular point and why this is not possible at the moment.

Attached resource:

Wayne van Gemert Replied at 3:48 AM, 17 Jul 2017

Last month the WHO Global TB Programme, Department of HIV and Global Hepatitis Programme released a joint information note on “Considerations for adoption and use of multidisease testing devices in integrated laboratory networks”. The document provides a strategic overview of key implementation considerations for diagnostic integration using testing devices for TB, HIV and viral hepatitis, and covers the following topics: coordinated planning; regulatory approval and validation; product and site selection; integrated specimen referral systems; standard operating procedures and trainings for end users; ensuring capacity for supervision, monitoring and conducting trainings; clinician training and demand generation; inventory management; quality management systems; and data management and integration.

The information note also includes a case study on adoption and use of GeneXpert by TB and HIV programmes.

It can be downloaded here: http://www.who.int/tb/publications/2017/considerations_multidisease_testing_d...

Wayne van Gemert
WHO Global TB Programme

Attached resource:

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