A significant proportion of people who experienced failure of HIV treatment have resistance to tenofovir, one of the key drugs used in HIV treatment. Tenofovir is a component of the tablets Viread, Truvada, Atripla, Eviplera and Stribild.
This story has been widely reported in the mainstream media, but not always accurately. Media reports may have given the impression that, in some regions, half of all people with HIV have resistance. In fact, the study only looked at people who had taken tenofovir and whose treatment did not work (they did not maintain an undetectable viral load).
It’s unsurprising that some drug resistance is found when treatment fails. But resistance to tenofovir develops more slowly than resistance to some other antiretrovirals – the high rates of tenofovir resistance seen in people in Africa in this study may reflect groups of patients not receiving frequent viral load testing. When viral load testing is available, it helps quickly identify treatment failure and people can be switched to another treatment before tenofovir resistance develops.
The study found that after treatment failure, the proportion of people with tenofovir resistance ranged from 20% in Western Europe to 60% in sub-Saharan Africa.
Given that between 15% and 35% of people who begin tenofovir-based treatment in African countries have treatment failure, between 8% and 18% of people starting tenofovir-based treatment there may have tenofovir resistance within a year.
People with HIV subtype C – common in people from sub-Saharan Africa, India and Brazil – were more likely to have resistance than other people. This also applied to migrants and other people with this subtype in Europe.
People beginning treatment with a very low CD4 cell count (below 100) and people also taking nevirapine (Viramune) or lamivudine (3TC, Epivir) were more likely to have resistance. This may reflect people receiving sub-optimal treatment – treatment should be begun at much higher CD4 cell counts. Further, more powerful drug combinations are currently recommended.
When higher quality healthcare is provided, rates of resistance are lower.
For more on drug resistance, you may find some of our information resources helpful. For example, the booklet ‘Taking your HIV treatment’ explains drug resistance and why taking your HIV treatment is so important. In our illustrated series, ‘The basics’, there is a title on ‘Drug resistance’. And our online tool ‘Talking points’ is designed to help you prepare any questions about HIV treatment you might have for your next clinic appointment.
This article first appeared in HIV Update, a publication of aidmsap.com here.