Paper # 1002|
Rapid HIV Screening: Missed Opportunities for Diagnosis and Prevention.
Pragna Patel*1, B Bennett2, T Sullivan3, M Parker3, J Heffelfinger1, P Sullivan4, and CDC AHI Study Group
1CDC, Atlanta, GA, US; 2Florida Bureau of Labs, Jacksonville, US; 3New York State Dept of Hlth, Albany, US; and 4Emory Univ, Rollins Sch of Publ Hlth, Atlanta, GA, US
Background: Although rapid HIV tests increase the
number of persons who are aware of their HIV status, the tests may have limited
sensitivity for the diagnosis of early HIV infection, resulting in missed
opportunities for HIV prevention. We evaluated the sensitivity for early HIV
infection of several rapid tests and third and fourth generation assays
compared with nucleic acid amplification testing (NAAT).
Methods: In the CDC Acute HIV Infection study,
persons underwent routine HIV antibody screening at 96 clinics in 3 US cities. Specimens
that were negative or indeterminate by serologic testing underwent NAAT. To evaluate
sensitivity for early HIV infection using NAAT as a gold standard, all
NAAT-positive specimens underwent third generation testing with Genetic Systems
1/2 +O® and rapid testing with Multispot HIV-1/HIV-2. A subset was also
tested with 4 other rapid tests and the Architect HIV Antigen/Antibody Combo®,
a fourth generation assay.
Results: Of 99,111 specimens screened from April 2006
to March 2008, 60 were NAAT-positive/seronegative by 1 of 3 different immunoassays
and 2 were NAAT-positive/Western blot indeterminate. Third-generation testing correctly
detected antibody in 34 specimens (55%; 95%CI 42 to 67); Multispot detected antibody
in 16 (26%; 95%CI 16 to 38). Of the 62 specimens, 33 (53%) had sufficient
quantity for further testing. Third-generation testing correctly detected
antibody in 19 of 33 specimens (57%; 95%CI 40 to 73); Clearview Complete in 8
of 27 (30%; 95%CI 15 to 49); Unigold Recombigen HIV in 8 of 33: (24%; 95%CI 12
to 41); Clearview HIV 1/2 Statpak in 7 of 31 (23%; 95%CI 11 to 40); Oraquick
Advance Rapid HIV-1/2 in 7 of 32 (22%; 95%CI 10 to 39). The rapid tests
correctly detected antibody in 37 to 47% of cases detected by third generation
testing. The sensitivity for early HIV infection of the antigen/antibody combo
assay was 87% (95%CI 72 to 96).
Conclusions: Many FDA-approved rapid HIV tests failed
to detect half of the early HIV infection cases in whom antibody was present
and at least two-thirds of the cases detectable by NAAT. Rapid test
sensitivities for early HIV infection ranged from 23 to 31% compared with 55 to
57% for the third generation assay and 87% for the fourth generation assay. Programs
that screen high-incidence populations with rapid tests should consider supplemental
testing with NAAT. These data support the need for more sensitive antigen-based
point-of-care screening tests for early HIV infection.