title: False-positive HIV DNA PCR testing of infants: implications in a changing epidemic.
abstract: OBJECTIVE
  To examine false-positive HIV DNA polymerase chain reaction (PCR) test results in children, and the potential implications for the paediatric HIV epidemic in sub-Saharan Africa.
  
  
  METHODS
  A review was done of records over a 6-year period of children less than 18 months old at an HIV treatment site in South Africa, to evaluate those with an initial 'false'-positive HIV DNA PCR result, but later proven to be HIV-uninfected with HIV DNA PCR and/or quantitative HIV RNA PCR tests. We calculated the influence of changing HIV transmission rates on predictive values (PV) of HIV DNA PCR tests in a hypothetical population of all HIV-exposed infants over a 1-year period. (Positive PV: proportion of individuals with a positive test with disease; negative PV: proportion of individuals with negative test and no disease).
  
  
  RESULTS
  Of 718 children, 40 with an initial positive HIV DNA PCR test were subsequently proven to be HIV-uninfected, resulting in a positive PV of 94.4%. Most (75%) uninfected children had PMTCT interventions and were asymptomatic or mildly symptomatic (77.5%). Calculations using a test specificity of 99.4%, as reported previously, show a decrease in positive PV using a single-test strategy from 98.6% at 30% HIV transmission rate, to 94.8% at 10% transmission, to 62.5% at 1% transmission. Reduction in test specificity further decreases positive PV at low transmission rates.
  
  
  CONCLUSIONS
  Decreasing mother-to-child HIV transmission rates reduce the positive predictive value of a single HIV DNA PCR test result, necessitating adaptations to diagnostic algorithms to avoid misdiagnosis and inappropriate treatment, especially with early initiation of antiretroviral therapy in asymptomatic infants.
authors.affiliation: Department of Paediatrics, Kalafong Hospital, University of Pretoria, South Africa. ute.feucht@up.ac.za
authors.forename: Ute Dagmar
authors.initials: UD
authors.lastname: Feucht
authors.forename: Brian
authors.initials: B
authors.lastname: Forsyth
authors.forename: Mariana
authors.initials: M
authors.lastname: Kruger
mesh_terms: D017954:Africa South of the Sahara / Q000453:epidemiology; D004279:DNA, Viral / Q000032:analysis; D003951:Diagnostic Errors / Q000517:prevention & control / Q000706:statistics & numerical data; D005189:False Positive Reactions; D005260:Female; D006678:HIV / Q000235:genetics*; D015658:HIV Infections / Q000175:diagnosis / Q000453:epidemiology / Q000635:transmission; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D018445:Infectious Disease Transmission, Vertical / Q000706:statistics & numerical data*; D008297:Male; D016133:Polymerase Chain Reaction / Q000379:methods / Q000592:standards; D011237:Predictive Value of Tests; D011247:Pregnancy; D011251:Pregnancy Complications, Infectious / Q000453:epidemiology*; D012367:RNA, Viral / Q000032:analysis; D012680:Sensitivity and Specificity; D013997:Time Factors
chemical_list: D004279:DNA, Viral; D012367:RNA, Viral