YOU ARE HERE:
Changing treatment
The goal of anti-HIV treatment in people taking it for the first time is to reduce viral load to below 50 copies, a level which is sometimes called ‘undetectable’. When viral load does not fall to this level it is more likely that treatment will not suppress HIV for sustained periods of time. A continued rebound in viral load from very low levels means that treatment is failing. What may follow is a fall in the CD4 count, a possible risk of HIV-related illness, and an ongoing risk of developing drug resistance. This means that treatment which is not suppressing viral load to the undetectable level should be changed if there are other drugs available which do seem likely to achieve this.
Monitoring viral load
Sometimes viral load rises to just above the detectable level and then falls back below on the next test. This is called a ‘blip’, and means that viral load should be re-tested as soon as possible, ideally within two weeks. Though one-off blips may be caused by a problem with viral load testing itself, they should also be a trigger to consider other possible causes, such as drug interactions, adherence problems, illnesses or vaccinations.
Treatment would be considered to have failed to control HIV only if there have been two viral load tests at least two weeks apart which both show that viral load is above 50 copies. It is recommended that a test for drug resistance is done to help choose the replacement treatment, or, if this is not possible (i.e. if your viral load is too low to have a resistance test), that the replacement treatment involves a completely new set of drugs.
If treatment is being changed because of side-effects, but viral load is undetectable, it is okay to switch only the drug(s) causing problems. If there have been problems with adherence, the failing treatment should be replaced with drugs which are easy to take, and support with adherence should be provided.
Resistance testing
Some doctors may consider delaying a switch in treatment if viral load rebounds to a low level, such as between 500 and 1,000 copies. This is because tests for drug resistance, (which may help pinpoint which drugs are unlikely to be effective in the replacement treatment), are more reliable at viral loads above 1,000 copies. Choosing to delay may increase the risk of further drug resistance developing. Because of this risk, people whose viral load has rebounded above 1,000 copies may be better off stopping their treatment while waiting for the results of their drug resistance test. The timing of a switch in therapy will be influenced by the drug options you have available. If a second combination seems very likely to reduce your viral load to undetectable levels, then an earlier switch will offer the least possible risk of resistance developing. If you have a fewer drug options available, you may be more inclined to switch later.
The causes of treatment failure may be complex, and there is no clear evidence to guide the choice of replacement drugs.
Changing treatment after more than one treatment failure - salvage therapy.
Doctors often make a distinction when talking about people who need to change their HIV drugs for the first time and those who’ve already made changes before. The term ‘salvage therapy’ is often used to describe treatment for people who have already taken drugs from the major anti-HIV drug classes, although some people find this term offensive and many doctors and patients now prefer to say 'heavily treatment experienced.'
People whose HIV is resistant to a number of anti-HIV drugs may find it difficult to assemble a replacement regimen which can lower their viral load to undetectable levels. Nevertheless, much smaller reductions in viral load lead to health improvements. In people with advanced HIV disease, the CD4 count is a better predictor of future risk of ill health than viral load, and so it may be more important to look for potential for CD4 increase in a replacement regimen.
Salvage therapy is more likely to be successful where a new class of drugs can be added, or drugs to which the individual is sensitive rather than resistant; where therapy is changed at lower viral load levels; and where a resistance test is used to choose the new drugs. Drug level tests may also be useful.
Treatment interruptions usually lead to a rapid fall in the CD4 count and rise in viral load, and therefore they may present a risk to people who require salvage therapy. However, it is always important to consider whether the risks of continuing treatment might outweigh the risks of stopping.