Transient Detectable Viremia & The Risk of Viral Rebound in Patients from The Swiss HIV Cohort Study

Temporary increases in plasma HIV RNA ('blips') are common in HIV patients on combination antiretroviral therapy (cART). Blips above 500 copies/mL have been associated with subsequent viral rebound. It is not clear if this relationship still holds when measurements are made using newer more sensitive assays.

We selected antiretroviral-naive patients that then recorded one or more episodes of viral suppression on cART with HIV RNA measurements made using more sensitive assays (lower limit of detection below 50 copies/ml). We estimated the association in these episodes between blip magnitude and the time to viral rebound.

Four thousand ninety-four patients recorded a first episode of viral suppression on cART using more sensitive assays; 1672 patients recorded at least one subsequent suppression episode. Most suppression episodes (87 %) were recorded with TaqMan version 1 or 2 assays. Of the 2035 blips recorded, 84 %, 12 % and 4 % were of low (50–199 copies/mL), medium (200–499 copies/mL) and high (500–999 copies/mL) magnitude respectively. The risk of viral rebound increased as blip magnitude increased with hazard ratios of 1.20 (95 % CI 0.89-1.61), 1.42 (95 % CI 0.96-2.19) and 1.93 (95 % CI 1.24-3.01) for low, medium and high magnitude blips respectively; an increase of hazard ratio 1.09 (95 % CI 1.03 to 1.15) per 100 copies/mL of HIV RNA.

With the more sensitive assays now commonly used for monitoring patients, blips above 200 copies/mL are increasingly likely to lead to viral rebound and should prompt a discussion about adherence.

Below:  Survival curves with first blip magnitude either in categories (left) or as a continuous measure (right) [24]. Curves are shown for the first suppression episode (top) and for subsequent suppression episodes (bottom). All curves are for the same reference patient: a male who did not acquire HIV though injection drug use, starting a suppression episode in 2005 at the age of 40, on a non-nucleoside reverse transcriptase based regimen, with a CD4 cell count of 350 cells/μL and with HIV RNA measured using an Amplicor ultrasensitive assay

Read more at:  http://ht.ly/SvmAT

By: Jim Young^1*, Martin Rickenbach², Alexandra Calmy³, Enos Bernasconi⁴, Cornelia Staehelin⁵, Patrick Schmid⁶, Matthias Cavassini⁷, Manuel Battegay⁸, Huldrych F. Günthard⁹, Heiner C. Bucher¹⁸ and the Swiss HIV Cohort Study

¹Basel Institute for Clinical Epidemiology and Biostatistics, University Hospital Basel, Basel, Switzerland

²Institute of Social and Preventive Medicine, University of Lausanne, Lausanne, Switzerland

³Division of Infectious Diseases, University Hospital Geneva, Geneva, Switzerland

⁴Division of Infectious Diseases, Regional Hospital of Lugano, Lugano, Switzerland

⁵Department of Infectious Diseases, Bern University Hospital and University of Bern, Bern, Switzerland

⁶Division of Infectious Diseases and Hospital Epidemiology, Cantonal Hospital St. Gallen, St Gallen, Switzerland

⁷Division of Infectious Diseases, University Hospital Lausanne, Lausanne, Switzerland

⁸Division of Infectious Diseases and Hospital Epidemiology, University Hospital Basel, Basel, Switzerland

⁹Division of Infectious Diseases and Hospital Epidemiology, University Hospital and University of Zürich, Zurich, Switzerland