title: A Single Quantifiable Viral Load Is Predictive of Virological Failure in Human Immunodeficiency Virus (HIV)-Infected Patients on Combination Antiretroviral Therapy: The Austrian HIV Cohort Study.
abstract: Background.  Viral loads (VLs) detectable at low levels are not uncommon in patients on combination antiretroviral therapy (cART). We investigated whether a single quantifiable VL predicted virological failure (VF). Methods.  We analyzed patients receiving standard regimens with at least 1 VL measurement below the limit of quantification (BLQ) in their treatment history. The first VL measurement after 6 months of unmodified cART served as baseline VL for the subsequent analyses of the time to reach single VL levels of ≥200, ≥400, and ≥1000 copies/mL. Roche TaqMan 2.0 was used to quantify human immunodeficiency virus-1 ribonucleic acid. Factors associated with VF were determined by Cox proportional hazards models. Results.  Of 1614 patients included in the study, 68, 44, and 34 experienced VF ≥200, ≥400, and ≥1000 copies/mL, respectively. In multivariable analyses, compared with patients who were BLQ, a detectable VL ≤ 50 and VL 51-199 copies/mL predicted VF ≥ 200 copies/mL (hazards ratio [HR] = 2.19, 95% confidence interval [CI] = 1.06-4.55 and HR = 4.21, 95% CI = 2.15-8.22, respectively). In those with VL 51-199 copies/mL, a trend for an increased risk of VF ≥400 and VF ≥1000 copies/mL could be found (HR = 2.13, 95% CI = 0.84-5.39 and HR = 2.52, 95% CI = 0.96-6.60, respectively). Conclusions.  These findings support closer monitoring and adherence counseling for patients with a single measurement of quantifiable VL <200 copies/mL.
authors.affiliation: Department of Dermatology and Venereology, Medical University of Innsbruck,; Austrian HIV Cohort Study, Innsbruck.
authors.forename: Gisela
authors.initials: G
authors.lastname: Leierer
authors.affiliation: Department of Dermatology , Medical University of Vienna .
authors.forename: Katharina
authors.initials: K
authors.lastname: Grabmeier-Pfistershammer
authors.affiliation: Otto-Wagner Hospital , Vienna .
authors.forename: Andrea
authors.initials: A
authors.lastname: Steuer
authors.affiliation: Department of Dermatology and Venereology , Medical University of Innsbruck .
authors.forename: Mario
authors.initials: M
authors.lastname: Sarcletti
authors.affiliation: Department of Dermatology , General Hospital Linz .
authors.forename: Maria
authors.initials: M
authors.lastname: Geit
authors.affiliation: Department of Internal Medicine , General Hospital Graz-West .
authors.forename: Bernhard
authors.initials: B
authors.lastname: Haas
authors.affiliation: Department of Internal Medicine III With Hematology, Medical Oncology, Hemostaseology, Infectious Diseases, Rheumatology , Oncologic Center, Laboratory for Immunological and Molecular Cancer Research, Paracelsus Medical University , Salzburg .
authors.forename: Ninon
authors.initials: N
authors.lastname: Taylor
authors.affiliation: 1st Medical Department , General Hospital Klagenfurt , Austria.
authors.forename: Manfred
authors.initials: M
authors.lastname: Kanatschnig
authors.affiliation: Department of Dermatology and Venereology, Medical University of Innsbruck,; Austrian HIV Cohort Study, Innsbruck.
authors.forename: Michaela
authors.initials: M
authors.lastname: Rappold
authors.affiliation: Division of Infectious Diseases and Hospital Epidemiology , University Hospital Zurich, University of Zurich , Switzerland.
authors.forename: Bruno
authors.initials: B
authors.lastname: Ledergerber
authors.affiliation: Department of Dermatology and Venereology , Medical University of Innsbruck .
authors.forename: Robert
authors.initials: R
authors.lastname: Zangerle
keywords: HIV; cART; low-level viremia; viral load; virological failure