title: Factors Associated with Low-Level Viraemia and Virological Failure: Results from the Austrian HIV Cohort Study.
abstract: BACKGROUND
  In human immunodeficiency virus treatment adequate virological suppression is warranted, nevertheless for some patients it remains a challenge. We investigated factors associated with low-level viraemia (LLV) and virological failure (VF) under combined antiretroviral therapy (cART).
  
  
  METHODS
  We analysed patients receiving standard regimens between 1st July 2012 and 1st July 2013 with at least one viral load (VL) measurement below the quantification limit (BLQ) in their treatment history. After a minimum of 6 months of unmodified cART, the next single VL measurement within 6 months was analysed. VF was defined as HIV RNA levels ≥ 200 copies/mL and all other quantifiable measurements were classified as LLV. Factors associated with LLV and VF compared to BLQ were identified by logistic regression models.
  
  
  RESULTS
  Of 2276 participants, 1972 (86.6%) were BLQ, 222 (9.8%) showed LLV and 82 (3.6%) had VF. A higher risk for LLV and VF was shown in patients with cART interruptions and in patients with boosted PI therapy. The risk for LLV and VF was lower in patients from centres using the Abbott compared to the Roche assay to measure VL. A higher risk for LLV but not for VF was found in patients with a higher VL before cART [for >99.999 copies/mL: aOR (95% CI): 4.19 (2.07-8.49); for 10.000-99.999 copies/mL: aOR (95% CI): 2.52 (1.23-5.19)] and shorter cART duration [for <9 months: aOR (95% CI): 2.59 (1.38-4.86)]. A higher risk for VF but not for LLV was found in younger patients [for <30 years: aOR (95% CI): 2.76 (1.03-7.35); for 30-50 years: aOR (95% CI): 2.70 (1.26-5.79)], people originating from high prevalence countries [aOR (95% CI): 2.20 (1.09-4.42)] and in male injecting drug users [aOR (95% CI): 2.72 (1.38-5.34)].
  
  
  CONCLUSIONS
  For both VF and LLV, factors associated with adherence play a prominent role. Furthermore, performance characteristics of the diagnostic assay used for VL quantification should also be taken into consideration.
authors.affiliation: Department of Dermatology and Venereology, Medical University of Innsbruck, Innsbruck, Austria.|Austrian HIV Cohort Study, Innsbruck, Austria.
authors.forename: Gisela
authors.initials: G
authors.lastname: Leierer
authors.affiliation: Department of Dermatology, Medical University of Vienna, Vienna, Austria.
authors.forename: Katharina
authors.initials: K
authors.lastname: Grabmeier-Pfistershammer
authors.affiliation: Otto-Wagner Hospital, Department of Pulmonology, Vienna, Austria.
authors.forename: Andrea
authors.initials: A
authors.lastname: Steuer
authors.affiliation: Department of Dermatology, General Hospital Linz, Linz, Austria.
authors.forename: Maria
authors.initials: M
authors.lastname: Geit
authors.affiliation: Department of Dermatology and Venereology, Medical University of Innsbruck, Innsbruck, Austria.
authors.forename: Mario
authors.initials: M
authors.lastname: Sarcletti
authors.affiliation: Department of Internal Medicine, General Hospital Graz-West, Graz, Austria.
authors.forename: Bernhard
authors.initials: B
authors.lastname: Haas
authors.affiliation: 1st Medical Department, General Hospital Klagenfurt, Klagenfurt, Austria.
authors.forename: Manfred
authors.initials: M
authors.lastname: Kanatschnig
authors.affiliation: Department of Dermatology and Venereology, Medical University of Innsbruck, Innsbruck, Austria.|Austrian HIV Cohort Study, Innsbruck, Austria.
authors.forename: Michaela
authors.initials: M
authors.lastname: Rappold
authors.affiliation: Department of Dermatology and Venereology, Medical University of Innsbruck, Innsbruck, Austria.
authors.forename: Robert
authors.initials: R
authors.lastname: Zangerle
authors.affiliation: Division of Infectious Diseases and Hospital Epidemiology, University Hospital Zurich, University of Zurich, Zurich, Switzerland.
authors.forename: Bruno
authors.initials: B
authors.lastname: Ledergerber
authors.affiliation: Department of Internal Medicine III with Hematology, Medical Oncology, Hemostaseology, Infectious Diseases, Rheumatology, Oncologic Center, Laboratory of Immunological and Molecular Cancer Research, Paracelsus Medical University, Salzburg, Austria.
authors.forename: Ninon
authors.initials: N
authors.lastname: Taylor
mesh_terms: D000328:Adult; D019380:Anti-HIV Agents / Q000627:therapeutic use; D044966:Anti-Retroviral Agents / Q000627:therapeutic use; D001317:Austria; D005260:Female; D015658:HIV Infections / Q000188:drug therapy* / Q000821:virology*; D015497:HIV-1; D006801:Humans; D016015:Logistic Models; D008297:Male; D055118:Medication Adherence; D008875:Middle Aged; D015999:Multivariate Analysis; D011446:Prospective Studies; D012367:RNA, Viral / Q000097:blood; D012189:Retrospective Studies; D012307:Risk Factors; D015819:Substance Abuse, Intravenous; D017211:Treatment Failure; D019562:Viral Load; D014766:Viremia / Q000821:virology
chemical_list: D019380:Anti-HIV Agents; D044966:Anti-Retroviral Agents; D012367:RNA, Viral