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Research from the United Kingdom and United States in virology provides new insights
Over 7 years of combination antiretroviral therapy (CART), risk of initial virological failure of treatment has been cut at least in half, according to a multicohort analysis (1996-2002).
According to a study from England, "Triple-combination antiretroviral therapy for human immunodeficiency virus infection has been in use for almost a decade, but the extent to which treatment success has changed is uncertain. We examined risk of initial virological failure of CART according to the year of starting therapy. We included subjects from five complete clinic cohorts in Europe and Canada who started CART without previous antiretroviral therapy from 1996-2002 with one or more pre-CART viral load (VL) measurement and CD4 count."
"Based on the first VL measurement from 6-12 months after CART initiation, virological failure was defined as a VL of more than 500 copies/mL. We used the following 3 inclusion strategies:
"1) including all subjects, with missing VL measurement counted as virological failure (n=3825; strategy A);
"2) including all subjects with VL measurement (n=3120; strategy B); and
"3) including all subjects receiving antiretroviral therapy at VL measurement (n=2890; strategy C)," wrote F.C. Lampe and colleagues, Royal Free & University College Medical School, London.
"From 1996-2002, risk of virological failure fell from 38.9% to 24.8% for strategy A, 28.4% to 12.0% for strategy B, and 22.8% to 8.2% for strategy C," the researchers continued. "Estimated relative reductions in risk (95% confidence interval) over the 7-year period, adjusted for cohort, demographic factors, pre-CART VL and CD4 count, and previous AIDS, were 48% (39-56%), 64% (53-73%), and 79% (69-85%) for strategies A, B, and C, respectively. Reductions in risk were greatest from 1996-1999, with weaker trends subsequently. Trends remained but were attenuated after further adjustment for the starting regimen.
Over a 7-year period of CART use in clinical practice, risk of initial virological failure of treatment has halved at least,? the researchers concluded. "These data suggest the trend is due to improvements in CART regimens and greater effectiveness of their use."
Lampe and colleagues published their study in Archives of Internal Medicine (Changes over time in risk of initial virological failure of combination antiretroviral therapy - A multicohort analysis, 1996 to 2002. Arch Intern Med, 2006;166(5):521-528).
For more information, contact F.C. Lampe, Royal Free & University College, School of Medicine, Dept. Primary Care & Population Science, Royal Free Campus, Rowland Hill St., London NW3 2PF, England.
Study 2: According to recent research from the United States, GB virus C (GBV-C) infection is associated with a reduced HIV load.
"GBV-C infection is associated with delayed mortality in HIV-infected people in most, but not all, studies. Previous investigations of the effect of GBV-C viraemia on response to antiretroviral therapy (ART) were inconclusive."
"To determine the effect of GBV-C on ART, we retrospectively analysed plasma samples taken from patients in a prospective randomized clinical trial of ART in HIV-positive Brazilians," wrote I.E. Souza and colleagues, University of Iowa.
"GBV-C viraemia was characterized by testing stored serum samples from 175 participants by reverse transcriptase-polymerase chain reaction (RT-PCR). Subjects were randomized to receive indinavir (n=59), zidovudine and lamivudine (n=58), or zidovudine, lamivudine and indinavir (n=58). The effect of GBV-C viremia on the average change in HIV viral load and CD4 count following initiation of therapy was evaluated in a multiple regression analysis."