Background:  On June 1, 2000, New York State implemented legislation mandating named reporting of HIV infection.  Providers and laboratories are required to report the following events:  diagnoses of HIV, HIV-related illness in previously unreported individuals, positive Western blot, CD4<500, detectable viral load, as well as diagnoses of AIDS-defining conditions, which have been reportable since 1984.   In this study we assessed the ability of the HIV/AIDS Reporting System (HARS) to monitor incident vs. prevalent HIV in NYC over time and measure progress toward meeting the congressional objective of reducing HIV incidence.

Methods:  Specimens from individuals newly diagnosed with HIV (non-AIDS) by Western blot from state and city public laboratories, June 1, 2000 until June 30, 2002 (n = 2455, representing 25% of new HIV diagnoses [non-AIDS]), were tested with the less-sensitive enzyme immunoassay (LS-EIA).  This 2-step laboratory method distinguishes between incident (=6 months post-seroconversion) and prevalent (>6 months) HIV infection.

Results:  Among cases identified by first positive Western blot test during the study period, the proportion of incident HIV increased from 14.8% (95%CI:  11.6, 16.0) in the first half year of observation to 21% (95%CI:  17.3, 24.5) in the fourth half-year of observation.  MSM and persons infected through heterosexual transmission comprised a significantly higher proportion of incident HIV than of PLWHA (32% vs 26%; 28% vs 18%, p <0.05), whereas IDU comprised a significantly lower proportion of incident HIV than of PLWHA (11% vs. 26%, p <0.05).

Conclusions:   The specificity of HARS to incident HIV increased over the first 2 years of named HIV reporting in NYC, as the bolus of newly reportable cases diagnosed prior to June 1, 2000, gradually diminished.  The significant differences in the distribution of risk factors of the leading versus the trailing edge of the epidemic suggest that the epidemic continues to evolve and provide evidence that HARS is enhanced by methods such as STARHS that shed light on the epidemic’s leading edge.  Routine HARS-STARHS can assist jurisdictions to establish and track their incidence rates, evaluate the maturation of new HIV surveillance systems, evaluate public policy encouraging early detection, and evaluate the efficacy of prevention programming for specific target populations.

Keywords: surveillance