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  • Viral load tests ‘could transform HIV treatment failure’

Image credit: Clive Chilvers, Wellcome Images

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  • Viral load monitoring gives more accurate results than those in widespread use

  • Current tests can give false positives and lead to unnecessary drug switching

  • But cost and logistics of rolling out viral load testing are barriers to its use

[CAPE TOWN] Médecins Sans Frontières (MSF) is calling for an increased use of viral load monitoring to improve treatment outcomes of HIV patients, in its latest study on testing in Africa.

Of those suspected of treatment failure after standard HIV tests such as white cell counts and clinical signs, as many as 70 per cent could be unnecessarily switched to more toxic treatments because these tests can falsely suggest their first-line treatment is failing, MSF’s study reports.

Instead, viral load tests determine the amount of virus in a patient’s blood and can better monitor how someone is responding to treatment on antiretrovirals (ARVs). If levels are found to be ‘undetectable’ the drugs are suppressing HIV as they should and people are less likely to transmit the virus to others. But an elevated viral load indicates a problem.

“Viral load is the closest measure we have for how well antiretroviral treatment is working as opposed to other measures of the immune system,” says Jennifer Cohn, medical coordinator for MSF’s Access Campaign, which works to provide affordable drugs. “It lets us know if therapy is working or if we need to change their therapy to something else if the virus is continuing to reproduce to high levels.”

The research, presented at the 17th annual International Conference on AIDS and STIs in Africa (ICASA) in Cape Town, South Africa (7–11 December 2013), looked at three countries starting to implement viral load tests: Kenya, Malawi and Zimbabwe. It found that among people who were suspected of failing their treatment based on standard assessments only 30 per cent had a higher viral load than expected.

The remaining 70 per cent could be switched unnecessarily to more expensive second-line treatment if viral load testing was not subsequently used to confirm treatment failure, which could waste hard-pressed resources.

“In those countries where access to antiretroviral treatment is still low, the first priority should be to get them on treatment and retain them in care.”

Lut Lynen, Institute of Tropical Medicine 

Despite MSF and other organisations saying that viral load testing is the ‘gold standard’ for treatment monitoring, its high costs mean that use is low. A survey of 23 poor countries in 2012 revealed that while all included viral load monitoring in their HIV treatment guidelines it was available in only four.

“Costs are dependent on negotiations with manufacturers and pooled procurements,” says Cohn. “Countries that need a large amount of tests can reduce costs by buying a large volume [in one purchase]. Increasing the daily throughput of tests can also bring down the cost per test.”

The researchers suggest the US President’s Emergency Plan for AIDS Relief and the Global Fund to Fight AIDS, Tuberculosis and Malaria — two organisations that provide funding for HIV treatment in Africa — should pool their procurement to negotiate lower prices with companies.

But there are also organisational challenges. “My concern is the implementation cascade,” says Lut Lynen, head of the HIV/AIDS and infectious diseases unit at the Institute of Tropical Medicine in Antwerp, Belgium. This is about the logistics of transporting samples from the field to laboratories and then relaying the results back to healthcare workers.

“A colleague in Congo [reported] that the facility doing the viral load tests is 500 kilometres away and it takes six weeks to three months to get a result back — if ever.”

Lynen adds that access to treatment is still the priority. “A solution for treatment monitoring is an absolute necessity, but in those countries where access to antiretroviral treatment is still low, the first priority should be to get them on treatment and retain them in care.”
 
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