Evaluating New Definitions of Acute and Early HIV Infection from HIV Surveillance Data.

Background: The U.S. HIV staging system is being revised to more comprehensively track early and acute HIV infection (AHI). We evaluated our ability to identify known cases of AHI using King County (KC) HIV surveillance data.

Methodology: AHI cases were men who have sex with men (MSM) with negative antibody and positive pooled nucleic acid amplification (NAAT) tests identified through KC testing sites. We used KC surveillance data to calculate inter-test intervals (ITI, time from last negative to first positive test) and the serologic algorithm for recent HIV seroconversion (STARHS). For surveillance data, AHI was defined as an ITI of ≤ 30 days and early infection as an ITI ≤ 180 days or STARHS recent result. Dates of last negative HIV tests were obtained from lab reports in the HIV surveillance system or data collected for HIV Incidence Surveillance.

Results: Between 2005 and 2011, 47 MSM with AHI were identified by pooled NAAT. Of the 47 cases, 36% had ITI < 1 day, 60% had an ITI < 30 days, and 70% (95% CI=55-82%) had an ITI ≤ 6 months and would have been identified as early HIV infection. Of the 47, 38% had STARHS testing and 94% were STARHS recent.

Conclusion: MSM with known AHI were not identified by proposed definitions of AHI and early infection. These known AHI cases were frequently missed by HIV surveillance because concurrent negative antibody tests were not reported. Successful implementation of the revisions to the HIV staging system will require more comprehensive reporting.