Loss to follow-up (LTFU) is a serious problem in most sub-Saharan African ART programmes. If ART is interrupted or reduced, HIV again progresses, and this increases the risk of opportunistic infections and, ultimately, AIDS and death. In addition, the viral load of a patient who interrupts ART will rebound, and the probability of onward transmission increases. If tracing programmes can accelerate the return of lost patients, these patients may be less likely to transmit the virus, since the period of lapsed treatment is shortened. In this study, we created a mathematical model to determine whether tracing patients LTFU from ART programs would lower the rate of HIV transmission.
A recent randomized controlled trial demonstrated that antiretroviral therapy (ART) prevents HIV transmission. In successfully treated patients the HI virus in the blood is suppressed to undetectable levels and therefore the probability of transmitting the virus is extremely low. This new finding must be incorporated into the evaluation of the advantages and disadvantages of different ART provision strategies. The optimal strategy for monitoring treatment response and detecting treatment failure – routine viral load monitoring (rVL) or CD4 cell counts or clinical symptoms – has been the subject of continuous debate. We suspected that rVL could potentially prevent HIV transmission by making it easier to detect treatment failure earlier. We developed a mathematical simulation model to estimate potential transmission from 1,000 patients treated with ART with either rVL or CD4 monitoring.