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


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) or established infection (>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.

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