title: Comparative performance of the new Aptima HIV-1 Quant Dx assay with three commercial PCR-based HIV-1 RNA quantitation assays.
abstract: BACKGROUND
  Quantitative measurement of HIV-1 RNA levels in plasma ('viral load') plays a central role in clinical management. The choice of assay platform can influence results and treatment decisions.
  
  
  OBJECTIVE
  To compare the analytical performance of the new TMA-based Hologic Aptima(®) HIV-1 Quant Dx assay with that of three PCR-based assays: Abbott RealTime HIV-1, Qiagen Artus(®) HI Virus-1 QS-RGQ, and Roche CAP/CTM HIV-1 Test v2.
  
  
  METHODS
  Assay performance was evaluated using Acrometrix HIV-1 RNA Standard panels; the 3rd WHO HIV-1 RNA International Standard (12-500 copies/ml; 6 dilutions; 9 replicates); and plasma samples from 191 HIV-positive patients.
  
  
  RESULTS
  Aptima showed high (>0.99) precision, accuracy and concordance with the Acrometrix Standards across a wide dynamic range (2.0-6.7 log10copies/ml). Variance caused up to 2.1 (Aptima), 1.7 (RealTime), 7.5 (Artus), and 1.9 (CAP/CTM) fold changes in the International Standard quantifications at 50-500 copies/ml. HIV-1 RNA detection rates in plasma samples were 141/191 (74%), 119/191 (62%), 108/191 (57%), and 145/191 (76%) for Aptima, RealTime, Artus and CAP/CTM, respectively. For categorising samples either side of 50 copies/ml, Aptima had excellent agreement with RealTime (kappa 0.92; 95% CI 0.87-0.98); lowest agreement was with Artus (kappa 0.79; 95%CI 0.70-0.88). Aptima quantifications were mean 0.12 and 0.06 log10copies/ml higher compared with RealTime and CAP/CTM, respectively, and 0.05 log10copies/ml lower compared with Artus. Limits of agreement were narrowest when comparing Aptima to RealTime.
  
  
  CONCLUSIONS
  The new Aptima HIV assay is sensitive, precise, and accurate. HIV assays exhibit discordance at low HIV-1 RNA copy numbers.
authors.affiliation: Liverpool Clinical Laboratories, Liverpool, United Kingdom. Electronic address: mark.hopkins@rlbuht.nhs.uk.
authors.forename: Mark
authors.initials: M
authors.lastname: Hopkins
authors.affiliation: Liverpool Clinical Laboratories, Liverpool, United Kingdom.
authors.forename: Sarah
authors.initials: S
authors.lastname: Hau
authors.affiliation: Liverpool John Moores University, Liverpool, United Kingdom.
authors.forename: Caroline
authors.initials: C
authors.lastname: Tiernan
authors.affiliation: University of Liverpool, Liverpool, United Kingdom.
authors.forename: Athanasios
authors.initials: A
authors.lastname: Papadimitropoulos
authors.affiliation: Liverpool Clinical Laboratories, Liverpool, United Kingdom.
authors.forename: Anu
authors.initials: A
authors.lastname: Chawla
authors.affiliation: University of Liverpool, Liverpool, United Kingdom.
authors.forename: Apostolos
authors.initials: A
authors.lastname: Beloukas
authors.affiliation: University of Liverpool, Liverpool, United Kingdom.
authors.forename: Anna Maria
authors.initials: AM
authors.lastname: Geretti
mesh_terms: D015658:HIV Infections / Q000821:virology*; D015497:HIV-1 / Q000235:genetics / Q000302:isolation & purification*; D006801:Humans; D021141:Nucleic Acid Amplification Techniques / Q000592:standards*; D016133:Polymerase Chain Reaction / Q000379:methods; D012367:RNA, Viral / Q000097:blood* / Q000235:genetics; D011933:Reagent Kits, Diagnostic / Q000592:standards; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D019562:Viral Load / Q000379:methods*
chemical_list: D012367:RNA, Viral; D011933:Reagent Kits, Diagnostic
keywords: Analytical performance; Aptima HIV-1 Quant Dx assay; HIV-1 quantitation; TMA; Viral load