title: Comparative frequencies of HIV low-level viremia between real-time viral load assays at clinically relevant thresholds.
abstract: BACKGROUND
  The introduction of new real-time PCR HIV-1 assays with higher sensitivity and broader dynamic range has resulted in detection of low-level viremia (LLV) (≥ 50 copies/mL) in some patients who previously had undetectable HIV-1 viral load (VL) (<50 copies/mL) with end-point PCR assays. It is therefore important to compare the performance of end-point and newer real-time PCR assays at medically relevant decision points.
  
  
  OBJECTIVE
  The study compared the results obtained with the end-point COBAS(®) AMPLICOR HIV-1 MONITOR Test, v1.5 to those obtained by three real-time PCR assays COBAS(®) AmpliPrep/COBAS(®) TaqMan(®) HIV-1 Test; the COBAS(®) AmpliPrep/COBAS(®) TaqMan(®) HIV-1 Test, v2.0; and the Abbott RealTime™ HIV-1 test.
  
  
  METHODS
  A total of 391 plasma specimens from HIV-1-infected patients from three US cities were tested with all four assays. The correlation and concordance of results between real-time and end-point PCR assays were calculated.
  
  
  RESULTS
  There was a consistent and similar proportion (11.8-14.0%) of HIV-1 VL ≥ 50 copies/mL with the three real-time PCR assays for specimens recording <50 copies/mL on the end-point PCR assay. The real-time PCR assays correlated with the end-point PCR assay within generally accepted limits, but consistently quantified higher than the end-point PCR assay between 50 and 200 copies/mL. Discrepancies in results were associated with patient CD4+ cell count and antiviral medication class.
  
  
  CONCLUSIONS
  The clinical interpretation of VL results from real-time PCR assays should take into account their higher sensitivity at the lower quantitation range when assessing patients for disease progression and monitoring response to therapy in HIV-1-infected patients, in line with current treatment guidelines.
authors: Roche Molecular Diagnostics, Inc., 4300 Hacienda Drive, Pleasanton, CA 94588, USA. tri.do@roche.com
authors: Tri
authors: T
authors: Do
authors: John
authors: J
authors: Duncan
authors: Ann
authors: A
authors: Butcher
authors: Teri
authors: T
authors: Liegler
mesh_terms: D000293:Adolescent; D000328:Adult; D018791:CD4 Lymphocyte Count; D018450:Disease Progression; D005260:Female; D015658:HIV Infections / Q000175:diagnosis* / Q000453:epidemiology / Q000276:immunology / Q000821:virology; D015497:HIV-1 / Q000276:immunology / Q000472:pathogenicity; D006801:Humans; D008297:Male; D008875:Middle Aged; D012367:RNA, Viral / Q000032:analysis*; D011933:Reagent Kits, Diagnostic / Q000592:standards; D015203:Reproducibility of Results; D020133:Reverse Transcriptase Polymerase Chain Reaction / Q000379:methods; D012680:Sensitivity and Specificity; D014481:United States / Q000453:epidemiology; D019562:Viral Load / Q000276:immunology / Q000379:methods*; D014766:Viremia / Q000175:diagnosis* / Q000276:immunology / Q000821:virology; D055815:Young Adult
chemical_list: D012367:RNA, Viral; D011933:Reagent Kits, Diagnostic