Antiretroviral resistance testing in HIV-positive people
What is the aim of this review?
The aim of this review was to find out whether a drug resistance test for people living with HIV (starting antiretroviral therapy (ART) or already on ART but with unsuppressed HIV) would reduce the number of deaths or improve HIV suppression.
Drug resistance to ART implies that specific antiretroviral drugs will be less effective. This happens either because the virus has changed to become resistant, or because an individual was infected with a resistant virus. To determine which drugs will be less effective, healthcare providers may conduct a resistance test. Two kinds of resistance tests are available: the genotypic test, in which the virus is examined to determine which drugs it is resistant to, and the phenotypic test, in which the virus is exposed to antiretroviral drugs to see which one it is resistant to. Use of resistance tests is common only in high‐income countries. Before we prepared this review, we did not know how well the use of resistance tests may reduce the number of deaths and improve HIV suppression.
Cochrane review authors collected and analysed all relevant studies up to 26 January 2018 to answer this question and included 11 randomized controlled trials (published between 1999 and 2006) with a total of 2531 people. Trials included only people who had detectable HIV despite being on antiretroviral drugs; no trials included patients starting therapy for the first time. Studies were conducted in Europe, USA, or South America. Seven studies used genotypic testing, two used phenotypic testing, and two used both phenotypic and genotypic testing. Only one study was funded by a manufacturer of resistance tests.
Resistance testing probably made little or no difference to the risk of dying (moderate‐certainty evidence) or progression to AIDS (moderate‐certainty evidence). Resistance testing probably increased the chance of successful suppression of HIV replication (low‐certainty evidence) but probably made little or no difference in CD4 cell counts (cells affected by HIV) (moderate‐certainty evidence). Resistance testing made little or no difference in the number of people who experience medication side effects (low‐certainty evidence). No studies examined how many people developed a new opportunistic infection, and no studies examined patient quality of life.
For people for whom treatment no longer works, the use of resistance tests to select new treatments led to suppression of the HIV virus as measured by a blood test, but probably did not reduce the risk of death or progression to AIDS. Whether or not resistance testing provides any benefit for patients who are starting HIV treatment for the first time remains uncertain because no studies have evaluated this. These conclusions are based on studies conducted up to 12 years ago and included very few participants from low‐ and middle‐income countries.