Modelling Estonia's concentrated HIV epidemic. A case study

Autorid: Lai T , Rätsep M , Rüütel K , Trummal A , Kahur K , Nielsen S , Lauer J , Politi C , Habicht J
Väljaandja/tellija: Tervise Arengu Instituut, Sotsiaalministeerium, WHO Euroopa Regionaalbüroo
Märksõnad: HIV, AIDS, sugulisel teel nakkavad haigused, nakkushaigused, antiretroviirusravi, hinnangud, epideemiad, narkootikumid, haigestumus, riskirühmad, nakatumine, andmed
Välja antud: 2009
Tüüp: Uuring/analüüs
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Teooria ja metoodika
Terviseteenuste korraldus, kättesaadavus ja kvaliteet
Kirjeldus: There are various sources of data on HIV in Estonia, and several studies have been carried out as well. However, little has been done to collect this information and summarize it for policy purposes.
The present modelling exercise seeks to assemble a comprehensive summary from the available data to better understand the HIV epidemic in Estonia, identify data gaps, support planning and implementation of the national HIV prevention strategy and foster discussion among national experts. It began with a meeting of such experts, which formed the basis for the informal working group that authored this report and the broader network that helped gather data and validate the modelling results. Additionally, this report can also be used as an introductory theoretical manual for the modelling framework and process of the model used in this study.
Since injecting drug users (IDUs) are the population most affected by HIV in Estonia, we used the UNAIDS/WHO model of concentrated HIV epidemics. Most previous epidemiological modelling of HIV in Estonia has been based on this framework, and Estonian experts are relatively familiar with UNAIDS/WHO estimates. The total number of Estonians living with HIV was approximately 11 000 in 2008. This estimate is based on studies conducted among IDUs and other risk groups. As of April 2009, the cumulative number of diagnosed cases is approximately 7000, which indicates about 4000 undiagnosed cases. Comparing the modelled and diagnosed incidence rates over time shows that the diagnosis gap was probably largest in the beginning of the epidemic. Our results suggest that the diagnosis gap has decreased to approximately 10%. In addition, the actual incidence of HIV is decreasing due to high saturation of the major risk groups. The size of the total HIV-positive population and the magnitude of the diagnosis gap profoundly influence prevalence, treatment need and mortality estimates, both current and projected. Our model suggests that the number of infected people who now need antiretroviral treatment (ART) may be as high as 3000. This estimate implies that current ART coverage is less than 50% of need, leaving as many as 1800 people without the treatment they require. In turn, this suboptimal coverage greatly increases the risk of HIV transmission in the general population, since among people living with HIV (PLHIV), those who receive ART are much less infectious than those who do not. Universal ART coverage is one of the main tools for containing the HIV epidemic. The treatment gap is also a major source of disease burden and avoidable deaths. In addition, HIV infection is significantly implicated in the spread of several other diseases, of which tuberculosis (TB) is probably the most important for Estonia. Not only does the spread of HIV inevitably lead to increased TB incidence, but the course of TB infection is also more severe among PLHIV.
Finally, our projections indicate that increasing the availability, access and coverage of ART and other HIV services would significantly reduce HIV transmission in high-risk groups, decrease the risk of the disease spreading to low-risk groups and improve the health of PLHIV.