title: Impact of nucleic acid testing relative to antigen/antibody combination immunoassay on the detection of acute HIV infection.
abstract: OBJECTIVE
  To assess the addition of HIV nucleic acid testing (NAT) to fourth-generation (4thG) HIV antigen/antibody combination immunoassay in improving detection of acute HIV infection (AHI).
  
  
  METHODS
  Participants attending a major voluntary counseling and testing site in Thailand were screened for AHI using 4thG HIV antigen/antibody immunoassay and sequential less sensitive HIV antibody immunoassay. Samples nonreactive by 4thG antigen/antibody immunoassay were further screened using pooled NAT to identify additional AHI. HIV infection status was verified following enrollment into an AHI study with follow-up visits and additional diagnostic tests.
  
  
  RESULTS
  Among 74 334 clients screened for HIV infection, HIV prevalence was 10.9% and the overall incidence of AHI (N = 112) was 2.2 per 100 person-years. The inclusion of pooled NAT in the testing algorithm increased the number of acutely infected patients detected, from 81 to 112 (38%), relative to 4thG HIV antigen/antibody immunoassay. Follow-up testing within 5 days of screening marginally improved the 4thG immunoassay detection rate (26%). The median CD4 T-cell count at the enrollment visit was 353 cells/μl and HIV plasma viral load was 598 289 copies/ml.
  
  
  CONCLUSIONS
  The incorporation of pooled NAT into the HIV testing algorithm in high-risk populations may be beneficial in the long term. The addition of pooled NAT testing resulted in an increase in screening costs of 22% to identify AHI: from $8.33 per screened patient to $10.16. Risk factors of the testing population should be considered prior to NAT implementation given the additional testing complexity and costs.
authors.affiliation: aSEARCH bThe Thai Red Cross AIDS Research Centre, Bangkok, Thailand cCooper Human Systems, Nashua, New Hampshire, USA dHIV-NAT eDepartment of Retrovirology, Armed Forces Research Institute of Medical Sciences, United States Component, Bangkok, Thailand fUnited States Military HIV Research Program, Bethesda gWalter Reed Army Institute of Research, Silver Spring hThe Henry M. Jackson Foundation for the Advancement of Military Medicine, Bethesda, Maryland, USA.
authors.forename: Mark S
authors.initials: MS
authors.lastname: De Souza
authors.forename: Nittaya
authors.initials: N
authors.lastname: Phanuphak
authors.forename: Suteeraporn
authors.initials: S
authors.lastname: Pinyakorn
authors.forename: Rapee
authors.initials: R
authors.lastname: Trichavaroj
authors.forename: Supanit
authors.initials: S
authors.lastname: Pattanachaiwit
authors.forename: Nitiya
authors.initials: N
authors.lastname: Chomchey
authors.forename: James L
authors.initials: JL
authors.lastname: Fletcher
authors.forename: Eugene D
authors.initials: ED
authors.lastname: Kroon
authors.forename: Nelson L
authors.initials: NL
authors.lastname: Michael
authors.forename: Praphan
authors.initials: P
authors.lastname: Phanuphak
authors.forename: Jerome H
authors.initials: JH
authors.lastname: Kim
authors.forename: Jintanat
authors.initials: J
authors.lastname: Ananworanich
mesh_terms: D000293:Adolescent; D000328:Adult; D003365:Costs and Cost Analysis; D003955:Diagnostic Tests, Routine / Q000379:methods*; D005260:Female; D015658:HIV Infections / Q000175:diagnosis*; D006801:Humans; D007118:Immunoassay / Q000379:methods*; D008297:Male; D008875:Middle Aged; D025202:Molecular Diagnostic Techniques / Q000379:methods*; D012680:Sensitivity and Specificity; D013785:Thailand; D055815:Young Adult