Results from a recent study of HIV-positive adults in Switzerland show that following United States antiretroviral therapy treatment guidelines when deciding on initial therapy regimens results in a greater likelihood of successfully suppressing HIV.
The researchers also found that the vast majority of patients receive regimens that conform to guideline recommendations.
The authors stated that their results validate the recommendations in current guidelines as well as the utility of the guides in helping clinicians decide on initial regimens to prescribe.
“Our results suggest that, in the context of constant increase in the number of therapeutic options and knowledge on specific drug-related side-effects and interactions, the release of updated treatment recommendations as well as the promotion of their use are important to guarantee the best possible care of HIV infected patients,” wrote the study authors.
The United States Department of Health and Human Services releases treatment guidelines on when to start antiretroviral therapy and which initial combination regimens to use for previously untreated (treatment-naïve) people with HIV.
The guidelines contain preferred treatment regimens as well as alternative and acceptable regimens. Preferred regimens are recommended as the best treatment regimens for most people starting antiretroviral therapy.
The guidelines are intended for use by HIV care practitioners when treating HIV-positive adults and adolescents in the U.S. The most recent set of guidelines were released in October 2011 (see this).
According to the study authors, the U.S. guidelines are also used to determine initial treatment regimens for people with HIV in Switzerland, which no longer issues its own guidelines.
In this study, the researchers sought to determine how often the guidelines are followed by clinicians in Switzerland when prescribing antiretroviral regimens. They also attempted to determine whether following the guidelines led to better treatment outcomes, such as higher CD4 (white blood cell) counts or greater probability of successfully achieving an undetectable viral load (amount of virus in the blood).
The study included 4,189 previously untreated patients from seven different clinical sites in Switzerland. All patients began antiretroviral therapy between August 1998 and December 2007. Approximately two-thirds (68 percent) of the study participants were male, and three-quarters (75 percent) were Caucasian. About 42 percent of participants were between the ages of 31 and 40 when they started therapy.
Results showed that 73 percent of the study participants were prescribed one of the preferred first-line regimens as their initial antiretroviral therapy treatment. Five percent of participants were prescribed a regimen that violated the recommendations in the guideline. The definition of a violation regimen included regimens that consisted of fewer than three antiretroviral drugs or had three drugs but included a nucleoside reverse transcriptase inhibitor (NRTI) regimen base, or backbone, that was not recommended.
The most common type of regimen guideline violation was prescribing a non-recommended NRTI backbone (34 percent of violations).
Results also showed that participants who were prescribed a violation regimen were about half as likely to successfully achieve undetectable viral loads within a year after starting treatment. CD4 cell count increases were similar between the groups after one year, with an average increase of 185 cells per microliter in the group taking a recommended regimen, versus 152 cells per microliter in those on violation regimens.
Within the first year of treatment, 34 percent of patients on violation regimens switched to a different regimen, versus 25 percent of patients on recommended regimens.
Women and highly educated patients were more likely to receive violation regimens, as were participants who started the study with CD4 counts above 350 cells per microliter. The study authors speculated that these patients may negotiate more with their clinicians over which antiretrovirals to take.
Participants with high viral loads (between 10,000 and 100,000 copies per milliliter) were less likely to receive a violation regimen.
For more information, please see the study in PLoS One.
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