Evidence that, for those who can tolerate it, Highly Active Antiretroviral Therapy has a durable effect on viral load and CD4 cell counts was presented on Monday at the Ninth Annual Retroviruses Conference from two major clinic cohorts.
The Royal Free Hospital in London reported that of 237 treatment-naïve patients who started triple therapy and subsequently achieved a viral load below 50 copies/ml, only 5.4% experienced a viral load rebound above 50 copies/ml during the follow-up period, an average rebound rate of 1 person per 26 person years of follow-up. The majority of patients had been followed for at least two and a half years, and the maximum follow up period was 4.4 years. No cases of viral rebound were observed in patients with three or more years experience of HAART.
Fiona Lampe, the statistician who carried out the analysis, noted that if the observed rate of viral breakthrough were to continue, "the median time before viral breakthrough would be twenty years [but] considering currently available drugs there must be severe doubt as to whether people will be able to consistently adhere to their antiretroviral regimens for such long periods, but the hope is that future regimens will be sufficiently less toxic and more convenient to make this possible".
The Royal Free group also reported that of patients on treatment, the proportion with viral load below 50 copies has increased significantly since the first half of 1999, indicating improvements in prescribing practice and adherence. The proportion of patients on HAART for more than 30 weeks with viral load below 50 copies/ml increased from 78.9% to 88.1% (p
The proportion of patients with viral load below 50 copies in this clinic cohort matches the best results from clinical trials.
A team from San Francisco reported that after more than four years on treatment, patients with viral load below 1,000 copies were continuing to experience CD4 cell increases in the fourth year of Highly Active Antiretroviral Therapy, with a median increase between year 3 and 4 of +64 cells. Interestingly, this is the average annual CD4 cell decline observed in untreated people with HIV, suggesting that after the initial period of strong immune reconstitution in the first six months of therapy, the rate of CD4 reconstitution will slow and that individuals with lower baseline CD4 cell counts will take longer to return to normal, age-dependent adult CD4 cell levels.
Hunt P et al. Continued CD4+ T-cell count gains in patients with 4 years of suppressed viral load on HAART. Ninth Conference on Retroviruses and Opportunistic Infections, Seattle, abstract 480, 2002.
Lampe F et al. Recent trends in treatment use and virological suppression in a London HIV clinic population. Ninth Conference on Retroviruses and Opportunistic Infections, Seattle, abstract 477, 2002.
Lampe F et al. Viral rebound after suppression with HAART: experience from 237 people with viral load Ninth Conference on Retroviruses and Opportunistic Infections, Seattle, abstract 536, 2002.