Long-term follow-up of HIV-2-related AIDS and mortality in Guinea-Bissau: a prospective open cohort study

Background HIV type 2 (HIV-2) is considered more benign and has fewer pathogenic consequences than HIV type 1 (HIV-1) for most infected individuals. However, reliable estimates of time to AIDS and mortality among those with HIV-2 infection are absent. We therefore aimed to compare the time to AIDS and mortality, and the CD4 T-cell dynamics between those infected with HIV-1 and HIV-2. Methods We did a prospective open cohort study. We included all police officers with regular employment from police stations in both urban and rural areas of Guinea-Bissau since Feb 6,1990. We continued to include participants until Sept 28, 2009, and follow-up of HIV-1-positive and HIV-2-positive individuals continued until Sept 28, 2013. We collected blood samples at enrolment and at scheduled annual follow-up visits at police stations. We analysed longitudinal data from individuals infected with HIV-1 and HIV-2 according to time to AIDS, time to death, and T-cell dynamics. Time of HIV infection was estimated as the mid-timepoint between last HIV-seronegative and first HIV-seropositive sample. Data from an additional 2984 HIV-uninfected individuals from the same population were analysed to assess the effect of natural mortality on HIV-related mortality. Findings 872 participants tested HIV positive during the 23-year study period: 408 were infected with HIV-1 (183 infected before and 225 infected after enrolment) and 464 were infected with HIV-2 (377 before and 87 after enrolment). The median time from HIV infection to development of AIDS was 6.2 years (95% CI 5.4-7.1) for HIV-1 infection and 14.3 years (10.7-18.0) for HIV-2 infection (p<0.0001). The median survival time after HIV infection was 8.2 years (95% CI 7.5-8.9) for HIV-1 infection and 15.6 years (12.0-19.2) for HIV-2 infection (p<0.0001). Individuals who were infected with HIV-1 or HIV-2 before enrolment showed similar results. Comparison with uninfected individuals indicated limited confounding contribution from natural mortality. Mean CD4 percentages were higher in individuals with HIV-2 than in those with HIV-1 during early infection (28.0% [SE 1.3] vs 22.3% [1.7]; p=0.00094) and declined at a slower rate (0.4% [0.2] vs 0.9% [0.2] per year; 13=0.028). HIV-2-infected individuals developed clinical AIDS at higher mean CD4 percentages (18.2%, IQR 7.2-25.4) than HIV-1-infected individuals (8.2%, 3.0-13.8; p<0.0001). Interpretation Our results show that both HIV-1-infected and HIV-2-infected individuals have a high probability of developing and dying from AIDS without antiretroviral treatment. Copyright (C) 2018 Elsevier Ltd. All rights reserved.