Attia S, Egger M, Müller M, Zwahlen M, Low N. Sexual transmission of HIV according to viral load and antiretroviral therapy: systematic review and meta-analysis. AIDS. 2009 Apr 17. [Epub ahead of print]
Attia and colleagues aimed to synthesize the evidence on the risk of HIV transmission through unprotected sexual intercourse according to viral load and treatment with combination antiretroviral therapy. They conducted a systematic review and meta-analysis, searching Medline, Embase, and conference abstracts from 1996-2009. The authors included longitudinal studies of serodiscordant couples reporting on HIV transmission according to plasma viral load or use of antiretroviral therapy and used random-effects Poisson regression models to obtain summary transmission rates [with 95% confidence intervals, (CI)]. If there were no transmission events they estimated an upper 97.5% confidence limit. They identified 11 cohorts reporting on 5021 heterosexual couples and 461 HIV-transmission events. The rate of transmission overall from antiretroviral therapy-treated patients was 0.46 (95% CI 0.19-1.09) per 100 person-years, based on five events. The transmission rate from a seropositive partner with viral load below 400 copies/ml on antiretroviral therapy, based on two studies, was zero with an upper 97.5% confidence limit of 1.27 per 100 person-years, and 0.16 (95% CI 0.02-1.13) per 100 person-years if not on antiretroviral therapy , based on five studies and one event. There were insufficient data to calculate rates according to the presence or absence of sexually transmitted infections, condom use, or vaginal or anal intercourse. Studies of heterosexual discordant couples observed no transmission in patients treated with antiretroviral therapy and with viral load below 400 copies/ml, but data were compatible with one transmission per 79 person-years. Further studies are needed to better define the risk of HIV transmission from patients on antiretroviral therapy.
Editors’ note: This study underscores the considerable uncertainty about the risk of HIV transmission under ‘Swiss Commission’ conditions, that is, viral load below 40 copies/ml, no other sexually transmitted infection, and consistent adherence to antiretroviral treatment. The Commission stated ‘much lower than one per 100,000 acts of sexual intercourse’ whereas this systematic review and meta-analysis of existing data found them compatible with one new infection for every 79 person-years of follow-up (or 7900 acts of sexual intercourse, if the yearly average is 100 contacts). Further studies are needed to quantify HIV transmission risk in different populations, including men who have sex with men for whom there are no comparable published data. In the meantime, since the Swiss Commission statement January 2008 UNAIDS has continued to reassert the importance of correct and consistent condom use – a key part of positive prevention and a cornerstone of HIV prevention for people without HIV
Attia S, Egger M, Müller M, Zwahlen M, Low N. Sexual transmission of HIV according to viral load and antiretroviral therapy: systematic review and meta-analysis. AIDS. 2009 Apr 17. [Epub ahead of print]
Attia and colleagues aimed to synthesize the evidence on the risk of HIV transmission through unprotected sexual intercourse according to viral load and treatment with combination antiretroviral therapy. They conducted a systematic review and meta-analysis, searching Medline, Embase, and conference abstracts from 1996-2009. The authors included longitudinal studies of serodiscordant couples reporting on HIV transmission according to plasma viral load or use of antiretroviral therapy and used random-effects Poisson regression models to obtain summary transmission rates [with 95% confidence intervals, (CI)]. If there were no transmission events they estimated an upper 97.5% confidence limit. They identified 11 cohorts reporting on 5021 heterosexual couples and 461 HIV-transmission events. The rate of transmission overall from antiretroviral therapy-treated patients was 0.46 (95% CI 0.19-1.09) per 100 person-years, based on five events. The transmission rate from a seropositive partner with viral load below 400 copies/ml on antiretroviral therapy, based on two studies, was zero with an upper 97.5% confidence limit of 1.27 per 100 person-years, and 0.16 (95% CI 0.02-1.13) per 100 person-years if not on antiretroviral therapy , based on five studies and one event. There were insufficient data to calculate rates according to the presence or absence of sexually transmitted infections, condom use, or vaginal or anal intercourse. Studies of heterosexual discordant couples observed no transmission in patients treated with antiretroviral therapy and with viral load below 400 copies/ml, but data were compatible with one transmission per 79 person-years. Further studies are needed to better define the risk of HIV transmission from patients on antiretroviral therapy.
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