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Persistent Low-level Viremia Is Associated with Increased Risk of Virologic Failure and Mortality
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Reported by Jules Levin
CROI 2010 Feb 16-19 SF
Mark Hull*1, M Loutfy2, W Zhang3, A Shen3, E Druyts2, M Klein1, N Machouf4, A Rachlis2, J Montaner3, R Hogg3, and the Canadian Observational Cohort Collaboration
1Montreal Chest Inst, McGill Univ Hlth Ctr, Canada; 2Univ of Toronto, Canada; 3BC Ctr for Excellence in HIV/AIDS, Vancouver, Canada; and 4Clin Med l’Actuel, Montreal, Canada
Background: Detection of transient or persisting low-level viremia with plasma viral load (pVL) >50 copies/mL remains common amongst patients receiving antiretroviral therapy (ART). The purpose of this study was to evaluate the effect of ongoing viremia on risk of virologic rebound and mortality.
Methods: Data were derived from a multi-site Canadian cohort of HIV+ patients >18 years receiving ART between Jan 2000 and Dec 2008. Patients who achieved 2 consecutive pVL <400 copies/mL at least 30 days apart, with ≥6 subsequent pVL’s over 24 months of classification period (CP) were placed into 4 groups. Group 1(fully suppressed) maintained pVL<50 copies/mL throughout the CP. Group 2 (transient viremia) achieved pVL <50 copies/mL, and remained <50 copies/mL for ≥75% of CP, with 25% CP viremic 50 to 1000 copies/mL. Group 3 (short-term viremia) maintained < 50 copies/mL for 25% to 75% of CP with the remainder of CP viremic. Group 4 (long-term viremia) maintained pVL<50 copies/mL for ≤25% of CP with the remainder viremic. After the initial CP, patients were followed to determine time to viral rebound (defined as 2 consecutive pVL >1000 copies/mL) and time to death using Cox proportional hazards models, adjusted for age, gender, baseline CD4 and pVL, prior AIDS defining illness, year of first ART and hepatitis C status.
Results: Of 1674 patients, 84% were male, and median age was 41 (IQR 35 to 47) years. From time of initial suppression, median follow-up for virologic rebound (n = 1674) was 36 (IQR 25 to 53) months, while median follow-up for mortality outcomes (n = 1430) was 51 (IQR 35 to 70) months. Compared to Group 1, those in Group 2 had similar risk of subsequent viral rebound (hazard ratio (HR) 1.12; 95%CI 0.62 to 2.01), while Group 3 (HR 6.05; 95%CI 4.06 to 9.02) and Group 4 (HR 20.46; 95%CI 11.40 to 36.74) were more likely to experience virologic rebound. Those experiencing short-term low-level viremia (the subset with majority pVL ≤200 copies/mL within Group 3) were more likely to have associated viral rebound (HR 4.95; 95%CI 2.29 to 10.69) and mortality (HR 4.25; 95%CI 1.41 to 12.82) compared to those with the same pVL range but experiencing only transient viremia (within Group 2).
Conclusions: Compared to those maintaining pVL <50 copies/mL, those experiencing short-term viremia were more likely to have subsequent viral rebound, and those experiencing short-term low-level viremia were more likely to have subsequent viral rebound and death compared to those experiencing only transient low-level viremia.
References:
1Sklar P. AIDS 2002: 2035
2Havlir D. JAMA 2001:171
3Nettles R. CID 2004:1030
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