Starting antiretroviral treatment (ART) early in the course of HIV infection when the immune system is stronger results in better long-term health outcomes compared with delaying ART, according to findings presented at the IDWeek Conference in Washington, D.C.
The findings are based on an extended follow-up of participants in the National Institutes of Health-funded Strategic Timing of Antiretroviral Treatment (START) study. In 2015, START demonstrated a 57% reduced risk of AIDS and serious non-AIDS health outcomes among participants who began ART when their CD4+ T-cell counts—a key indicator of immune system health—were greater than 500 cells per cubic millimeter (mm³) compared with those who did not begin ART until either their CD4+ counts fell below 350 cells/mm³ or they developed AIDS. Following the 2015 report of these findings, the participants in the deferred treatment arm were advised to begin ART.
The international START study proved the benefit of early ART initiation, but longer-term follow-up of 4,446 participants was undertaken to determine whether the health benefits of early ART compared with deferred ART increased, remained constant, or declined after the participants in the deferred arm were advised to begin ART. The primary study endpoints included the number of participants who developed AIDS; those who developed serious non-AIDS health conditions, such as major cardiovascular disease, kidney failure, liver disease and cancer; and those who died.
For participants who began ART before the end of 2015, the median CD4+ cell count at the time of ART initiation was 648 cells/mm³ for the immediate arm and 460 cells/mm³ for the deferred arm. The analysis presented compared the primary study endpoints before the end of 2015, with those in the extended follow-up period, from Jan. 1, 2016, to Dec. 31, 2021. In the latter period, most deferred-arm participants were taking ART. During the second period, people initiating ART in the deferred group had rapid and sustained declines in HIV viral load (less than or equal to 200 copies/mL); however, CD4+ cell counts remained, on average, 155 cells lower compared with that of individuals in the immediate ART group. While the risk of serious health outcomes was substantially diminished soon after ART was initiated in the deferred treatment group, some excess risk remained compared with the immediate treatment group. The deferred ART group continued to have a somewhat greater risk (21%) of serious health consequences or death in comparison to the immediate treatment group. Twenty-seven cases of AIDS occurred in the five-year follow-up period in the deferred treatment group compared with 15 cases in the early treatment group. Similarly, 88 cases of serious non-AIDS health issues occurred in the deferred treatment arm compared with 76 cases in the immediate treatment arm. Lastly, there were 57 deaths in the deferred treatment group compared to 47 in the immediate treatment arm.
