January 23, 2012
Researchers have studied interruptions of antiretroviral therapy for various reasons. These treatment interruptions are usually called structured or strategic treatment interruptions (STIs), or structured intermittent therapy (SIT).
During most treatment breaks, the viral load climbs very quickly and CD4 cell counts drop. Some people get the same symptoms as if they were newly infected with HIV. Fact Sheet 103 has more information on acute HIV infection.
When people start medications again after taking a break, they might experience more side effects, like when they first started taking antiretroviral drugs (ARVs). They might also have difficulty with adherence (see Fact Sheet 405), taking all of their doses correctly.
There were several reasons why treatment interruptions were studied:
Unfortunately, this approach does not seem to work. There are several reasons. First, most people aren't aware that they have just been infected with HIV. Once HIV infection has continued for a few months, it's too late for this approach. Also, researchers cannot predict which patients might be able to stop their therapy. But most important, newer research shows that the immune response in these patients does not continue to protect them against HIV disease.
Some people started treatment with higher CD4 counts than the then-current guidelines. In some cases, their providers recommended that they stop taking medications. They checked their CD4 cell counts and their viral loads regularly. Most providers put these patients back on therapy when they met the current guidelines.
Two types of "cycling" were studied. The first type put patients on a fixed schedule. They would start and stop therapy for a certain number of days or weeks. The second type of cycling used CD4 counts and/or viral loads to decide when to end a treatment break and start medications again. Neither of these approaches seems to work.
During a treatment interruption, the "wild type" virus becomes more common. At first, researchers thought this was a good thing, because the wild type virus can be controlled by medications. However, the wild type virus does not replace all existing resistant strains. Resistance can come back quickly when drugs are re-started. Most patients do better if they keep taking medications, even if HIV is not totally controlled. A study in 2008 showed that patients who continued a "failing" regimen developed fewer AIDS-related medical problems than those who stopped their medications.
Do not stop your ART without careful discussion with your health care provider. Viral load and CD4 cell levels should be carefully monitored. Do not stop taking medications to prevent or treat opportunistic infections (see Fact Sheet 500).
The biggest risk of an STI is that you will develop an AIDS-related infection. Also, the viral load will probably climb and the CD4 count will drop. These risks are greatest for people who have a low CD4 count. If you have only 50 CD4 cells, losing another 10 might have serious consequences. Stopping medications to prevent opportunistic infections can allow them to develop. A research study on STIs showed that people who stopped treatment had a much higher chance of developing an opportunistic infection. People infected with hepatitis B who stopped ART were much more likely to experience a flare of their hepatitis than those who continued treatment.
Stopping and re-starting medications could make it easier for the virus to develop resistance to medications. This has happened to some patients in STI studies.
People ending a treatment interruption might have a hard time re-starting medications. This can be due to side effects, or due to psychological difficulties in getting back on treatment.
HIV patients stop ART for various reasons. If we can learn how to use treatment interruptions safely, patients might be able to take periods of time off of ARVs. However, we will have to learn how to avoid HIV disease progression, and minimize drug resistance and transmission of HIV. So far, large research studies have not shown any benefits to discontinuing therapy.