Recent HIV seroconversion at time of first positive test : a comparison before and after HIV reportability

Background: HIV was added to the British Columbia list of reportable diseases on 1 May 2003 which included enhanced contact tracing by public health. A sensitive/less-sensitive (S/LS) algorithm using a modified EIA anti-HIV assay was employed to evaluate enhanced partner notification by comparing the proportion of newly diagnosed cases of HIV presenting within 6 months of becoming infected before and after HIV Reporting. Methods: Banked HIV positive samples, collected between 1 Jan 2000– 30 Apr 2003 (pre-reporting group) and 1 May 2003 – 23 Aug 2006 (post-reporting group) were re-tested using the bioMérieux Vironostika HIV-1-S/LS tests. Samples were classified by the S/LS EIA (detuned test) as a recent seroconversion (RSC) (infected for 170 days). Data was linked to the BC HIV Surveillance and AIDS databases. The proportion of RSC in the pre-reporting group was compared to the proportion of RSC in the post-reporting group using a 2-sided z-test of independent proportions. Similarly, the proportion of new cases of HIV presenting with AIDS was compared between groups. A Kappa statistic was calculated to determine the level of agreement between clinical assessment of HIV staging was compared and the detuned test results. Finally, characteristics of RSC were examined. Results: Serum was available for 1111 newly positive HIV cases in the pre-reporting group and 470 in the post-reporting group. RSC in the pre and post reporting group were 311 (28%; CI: 25.36%, 30.73%) and 136 (29%; CI: 24.87%, 33.27%) respectively (p= 0.70). There was no significant difference in the proportion of cases presenting with AIDS between groups (pre-reporting: 6.7% [CI: 5.4%, 8.1%]; post-reporting: 7.6% [CI: 6.3%, 9.1%]) (p=0.31). Sex work is independently associated with being RSC (AOR 1.78 [CI:1.09, 2.91]). There is an inverse association between being 41-60 yrs old, Asian and/or mixed ethnicity and RSC. Conclusions: The bioMérieux Vironostika HIV-1-S/LS test is an effective tool to objectively evaluate public health interventions and in identifying sub-populations likely to be RSC. This underpowered study demonstrated a slight increase in RSC post reporting which was not statistically significant. Similarly there was no difference in the proportion of cases presenting with AIDS.Medicine, Faculty ofPopulation and Public Health (SPPH), School ofGraduat