title: Evaluation of filter paper transfer of whole-blood and plasma samples for quantifying HIV RNA in subjects on antiretroviral therapy in Uganda.
abstract: BACKGROUND
  Most HIV-infected subjects on antiretroviral therapy (ART) in resource-limited settings do not undergo virologic monitoring. There is an urgent need for cheap, accessible HIV RNA assays for early diagnosis of virologic failure. We investigated filter paper transfer (FPT) of whole blood and plasma as an alternative to standard plasma-based assays for virologic monitoring in Uganda.
  
  
  METHODS
  Whole blood (n = 306) and plasma (n = 218) from 402 subjects established on ART were spotted onto filter paper and transported to Europe for HIV RNA extraction and quantification. These results were compared to a gold standard plasma assay in Kampala.
  
  
  RESULTS
  Of 402 ART-treated subjects, 39 (9.7%) had viremia detectable (>500 copies/mL) by local methods. Plasma FPT showed excellent agreement with gold standard, whereas whole blood yielded a large number of false-positive viral loads.
  
  
  CONCLUSIONS
  This is the first study to investigate the use of FPT in ART-treated subjects and demonstrates that it may provide a practical, reliable method for virologic monitoring in resource-poor settings. Plasma FPT was accurate but requires centrifuge; whole blood produced a high number of false-positive results, but these were low-level. Whole blood may be sufficiently accurate if higher HIV RNA cut-offs were used to define virologic failure.
authors.affiliation: St. Stephens AIDS Trust, Chelsea & Westminster Hospital, London, UK. laura.waters@btinternet.com
authors.forename: Laura
authors.initials: L
authors.lastname: Waters
authors.forename: Andrew
authors.initials: A
authors.lastname: Kambugu
authors.forename: Hilda
authors.initials: H
authors.lastname: Tibenderana
authors.forename: David
authors.initials: D
authors.lastname: Meya
authors.forename: Laurence
authors.initials: L
authors.lastname: John
authors.forename: Sundhiya
authors.initials: S
authors.lastname: Mandalia
authors.forename: Maggie
authors.initials: M
authors.lastname: Nabankema
authors.forename: Irene
authors.initials: I
authors.lastname: Namugga
authors.forename: Thomas C
authors.initials: TC
authors.lastname: Quinn
authors.forename: Brian
authors.initials: B
authors.lastname: Gazzard
authors.forename: Steven J
authors.initials: SJ
authors.lastname: Reynolds
authors.forename: Mark
authors.initials: M
authors.lastname: Nelson
mesh_terms: D019380:Anti-HIV Agents / Q000627:therapeutic use; D001769:Blood / Q000821:virology*; D001774:Blood Chemical Analysis; D005189:False Positive Reactions; D015658:HIV Infections / Q000188:drug therapy / Q000821:virology*; D006801:Humans; D010949:Plasma / Q000737:chemistry / Q000821:virology*; D011237:Predictive Value of Tests; D012367:RNA, Viral / Q000032:analysis*; D013048:Specimen Handling / Q000379:methods*; D014454:Uganda
chemical_list: D019380:Anti-HIV Agents; D012367:RNA, Viral