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48th Annual ICAAC / IDSA 46th Annual Meeting
October 25-28, 2008
Washington, DC
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Doubled Risk of Failure After 1 Year Under 50 Copies in Women and Steady Blippers
  48th ICAAC, October 25-28, 2008, Washington, DC
Mark Mascolini
Women, people with repeated transient low-level viremia (blips) during their first year of therapy, and people taking a ritonavir-boosted protease inhibitor (PI) rather than a nonnucleoside ran about twice the risk of first-line regimen failure after good viral control in the first year of treatment. This study at two HIV clinics in London and Frankfurt focused on 1386 people starting their first antiretroviral combination from 1996 through 2005. The study group was 79.4% male and 63.3% white. While 81.8% were born in Europe, 6.7% were born in Africa, and 11.5% elsewhere; 63.3% were white, 24.7% were black African, and 12.0% belonged to another racial or ethnic group. Just over half of the cohort, 56.7%, became infected during sex between men. While 1032 people (74.5%) kept their viral load under 50 copies after reaching that mark, 269 (19.4%) had transient low-level viremia (blips) in the following year, and 85 (6.1%) had persistent low-level rebounds, defined as 2 or more consecutive viral loads between 50 and 400 copies.
At a median 2.2 years of follow-up after the first year of therapy (range 0 to 7.4 years), 86 people (6.2%) endured virologic failure, defined as consecutive viral load readings above 400 copies or a single 400-copy load followed by a regimen change or the end of follow-up while still taking antiretrovirals. That translated into a failure rate of 2.3 per 100 person-years (95% confidence interval [CI] 1.82 to 2.79).
Multivariate analysis sorted out four independent predictors of failure at the following odds ratios (OR) and 95% CIs:
⋅ Female gender: OR 1.79 (1.12 to 2.85)
⋅ Consecutive blips: OR 2.18 (1.15 to 4.10)
⋅ Boosted PI versus nonnucleoside: OR 1.88 (1.02 to 3.46)
⋅ Triple-nucleoside or other regimen versus nonnucleoside: OR 1.87 (1.04 to 3.36)
Factors that did not predict failure were age, HIV transmission risk group, year of first viral load below 50 copies, time to viral load below 50 copies, pre-HAART CD4 count, and drug changes due to toxicity.
Anna Maria Geretti of London's Royal Free Hospital attributed the higher rebound risk among women to the make-up of the study population. Most women at both the London and Frankfurt sites are poor African women with social impediments to consistent HIV care. Most of the men are white gay Europeans. Geretti suggested that nonnucleoside regimens have an edge over boosted PIs because they cause fewer side effects and thus encourage better adherence.
The investigators believe their findings "identify a subset of patients who should be targeted by specific intervention to optimise adherence, drug levels and tolerability."
1. Geretti A, Smith C, Garcia-Diaz A, et al. Gender, treatment regimen, and occurrence of confirmed low-level viremia predict virologic failure after initial viral load suppression in first-line HAART. 48th Annual International Conference on Antimicrobial Agents and Chemotherapy (ICAAC). October 25-28, 2008. Washington, DC. Abstract H-1256.