February 25, 2011
The current study was designed to determine how the risk of transmission from HIV-infected gay men receiving antiretroviral treatment relates to patterns of patient monitoring and condom use.
A stochastic mathematical simulation model was developed of Netherlands men who have sex with men (MSM), defining the parameters of the model using observational cohort data. Included in the model are viral load trends during first-line treatment, patient monitoring and various scenarios for the way in which condom use may depend on recent viral load measurements. Not included was the effect of STDs on HIV transmission.
The results showed that for MSM receiving treatment, the risk of transmitting HIV to their long-term partner is 22 percent (uncertainty interval: 9-37 percent) if condoms are never used. With incomplete condom use (30 percent of sex acts), the risk is reduced to 17 percent (7-29 percent). When men receiving treatment use condoms only six months beyond their last undetectable viral load measurement, the risk is as low as 3 percent (0.2-8 percent). "The risk is further reduced when three months is the time period beyond which condoms are used," the authors wrote.
The authors stressed the following messages:
"When condom use by HIV-infected men receiving combination treatment with antiretroviral agents is based on their last viral load measurement, the transmission risk is much lower than with incomplete condom use. The key message for patients is that although always using condoms during treatment is the best way to protect partners from the risk of HIV transmission, when such use cannot be achieved, the second-best strategy is to use condoms whenever the last undetectable viral load was measured more than three months ago," the authors concluded.