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Low-Level Viremia Quadruples Death Risk in Canadian Cohort Study
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17th Conference on Retroviruses and Opportunistic Infections, February 16-19, 2010, San Francisco
Mark Mascolini
Short-term low-level rebounds in HIV RNA during otherwise suppressive therapy quadrupled the risk of death compared with briefer low-level rebounds (often called "blips") in a multisite Canadian cohort of adults beginning antiretroviral therapy between January 2000 and December 2008 [1]. People with short- or long-term viremia proved more likely to have a full viral rebound in 36 months of follow-up than people with sustained viral control.
The study involved 1674 adults who registered consecutive viral loads below 400 copies after starting therapy and had at least six subsequent viral load assays in 2 years. The investigators divided them into four groups:
· Group 1: Full suppression (always below 50 copies)
· Group 2: Transient viremia: reached and maintained a load below 50 copies for more than 75% of follow-up, with viremic episodes between 50 and 1000 copies
-Subset of transient low-level viremia: most viremic episodes below 200 copies
· Group 3: Short-term persisting viremia: reached and maintained a load below 50 copies for 25% to 75% of follow-up
-Subset of persisting low-level viremia: most viremic episodes below 200 copies
· Group 4: Long-term persisting viremia: Reached and maintained a load below 50 copies for less than 25% of follow-up
During follow-up the researchers measured time to rebound, defined as two consecutive loads above 1000 copies, and time to death.
Most cohort members (84%) were men, and median age measured 41 years (interquartile range [IQR] 35 to 47). Median follow-up time for virologic rebound was 36 months (IQR 25 to 53), and median follow-up for death (in 1430 people) was 51 months (IQR 35 to 70).
Compared with the full-suppression Group 1, Group 2 with transient viremia had a similar risk of later full rebound (hazard ratio [HR] 1.12, 95% confidence interval [CI] 0.62 to 2.01). However, compared with Group 1, people in Group 3 had a 6 times higher rebound risk (HR 6.05, 95% CI 4.06 to 9.02) and people in Group 4 had a 20 times higher risk (HR 20.46, 95% CI 11.40 to 36.74).
Compared with the Group 2 subset with transient low-level viremia, the Group 3 subset with persisting short-term low-level viremia had a 5 times higher rebound risk (HR 4.95, 95% CI 2.29 to 10.69) and a 4 times higher risk of death (HR 4.25, 95% CI 1.41 to 12.82).
The investigators stressed that "sustained virologic suppression remains an important target" with antiretroviral therapy.
Reference
1. Hull M, Loutfy M, Zhang W, et al. Persistent low-level viremia is associated with increased risk of virologic failure and mortality. 17th Conference on Retroviruses and Opportunistic Infections. February 16-19, 2010. San Francisco. Abstract 504.
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