Is HIV drug resistance spreading? Early warning signals say 'yes'
Mar 11th, 2011 - 05:30:48
Signals warning of the transmission of drug-resistant HIV are growing in
low- and middle-income countries, and governments should step up
surveillance efforts as they scale up treatment, experts concluded today at
the Eighteenth Conference on Retroviruses and Opportunistic Infections
(CROI) in Boston.
A World Health Organization (WHO) survey of 'early warning indicators'
levels of performance that treatment services should be hitting in order to
minimise the risk of drug resistance showed substantial problems with drug
stock-outs, loss to follow-up and patients picking up drugs on time in nine
African countries in 2008.
Research by PharmAccess, a Dutch foundation that provides HIV treatment
services for the private sector in sub-Saharan Africa, shows that levels of
transmitted drug resistance across eleven countries showed that the risk of
identifying transmitted drug resistance increased by 38% for each year that
a country had been scaling up antiretroviral treatment.
Furthermore, a survey of recently infected young people in Kampala, Uganda,
showed that 8.6% had evidence of drug-resistant virus, with resistance to
all three classes of antiretroviral drug currently available in the country
detected among the sample.
In Latin America, rates of transmitted drug resistance may run as high as
20% in some parts of Brazil, and 6.8% in Mexico, researchers reported.
*Transmission of drug resistance*
Viruses resistant to drugs used in HIV treatment may be transmitted by
people on treatment that is failing, or by people who have stopped or
interrupted treatment. The best way of preventing the transmission of
drug-resistant virus, apart from consistent condom use during sex, is to
ensure that doses of medication are never missed.
However, interruptions in drug supply and difficulties in reaching the
clinic to pick up drugs, often due to poverty or fluctuating income, mean
that even patients with good adherence to treatment may be blocked in their
efforts to take medication consistently.
For this reason the World Heath Organization developed a set of early
warning indicators that are being monitored at a large sample of HIV clinics
in sub-Saharan Africa, in order to give advance notice of problems, and to
provide feedback to clinics on how they are doing.
*Early warning indicators*
A review of clinic performance in sub-Saharan Africa in 2008 found that in
respect to indicators most likely to affect adherence, clinics needed to
improve substantially to minimise the risk of resistance.
*Early warning indicators*
Survey of 130 clinics in 9 countries, 2008
*Proportion of clinics reaching target*
100% prescription of WHO first-line recommended regimens
< 20% loss to follow-up
>70% retention on appropriate first-line regimen
>90% of patients picking up prescribed ARVs on time
>80% of clinic appointments attended as scheduled
100% of drugs available at pharmacy at all times
PharmAccess carried out a review of drug resistance in 2478 treatment-naive
patients commencing antiretroviral treatment at 13 sites in eleven
countries, and found an overall prevalence of 5.71% (95% confidence interval
4.82 to 6.70%). Resistance to all three drug classes was found (NRTIs 2.2%,
NNRTIs 3.41% and PIs 1.27%). The presence of resistance at a site was
significantly associated with the time since the initiation of ART provision
in that geographic area (odds ratio 1.56, p