The current Russian policy of providing antiretroviral therapy to individuals who do not inject drugs does not make any public health, or economic sense, according to a study published in the November 14th edition of AIDS. Using a mathematical model assessing the public health benefits and economic cost of a number of HIV treatment strategies, American investigators calculated that treating both HIV-positive individuals who did not inject drugs and those who did inject drugs, was the strategy that would prevent the most new HIV infections over a 20 year period and cost only $300 more per year per life-year gained than the most conservative strategy, which provided treatment only to patients who did not inject drugs.
Officially the number of HIV cases in Russia is 300,000, but the actual figure is thought to be closer to 850,000, with 90% of these infections occurring since 2000. Over three-quarters of all HIV infections in Russia are attributed to injection drug use, and as there are between 1.5 million and 3 million registered injection drug users in Russia, the potential for the further spread of HIV is enormous.
Because of fears about poor adherence, virtually no current injecting drug users in Russia receive treatment with antiretroviral therapy. Indeed, only 5,000 individuals in the whole of Russia received antiretroviral therapy in 2005, but there are hopes that treatment programmes will increase this figure to over 30,000 during 2007.
Against this background of HIV risk behaviour and antiretroviral availability, investigators wished to see how effective the current strategy of only treating HIV-positive individuals who did not inject drugs was, both in terms of the number of new infections it prevented and the overall cost of HIV therapy and other healthcare.
A mathematical model based on the prevalence of injecting drug use and HIV infection in St Petersburg was therefore developed which can be accessed here. A number of possible strategies, making HIV therapy available to various population groups were included in the model.
St Petersburg was selected by the investigators because it has a high prevalence of both injecting drug use (4% of the adult population) and HIV (35% of injecting drug users are HIV-positive, and 0.6% of individuals who do not inject drugs). To see how application their model was to a setting with a lower HIV prevalence, the model was also tested on the Siberian city of Barnaul (6% injecting drug users, 2% HIV prevalence amongst injecting drug users and 0.06% amongst individuals who do not inject drugs).
The investigators calculated that HIV treatment would be used in accordance with current US treatment guidelines, and that therapy would be initiated once an individual’s CD4 cell count fell to 350 cells/mm3. They estimated that treatment would cost $1950 per annum, and that injecting drug users would require additional support service costing $500 per year, and all HIV-positive individuals were calculated to have non-antiretorviral treatment costs of $570 per year. Other medical costs were calculated at $115 per annum for all individuals.
Treating HIV with antiretrovirals was estimated to reduce the annual risk of HIV-related death by 20% and to lead to a six-fold reduction in the risk of progression from symptomatic HIV disease to AIDS.
The investigators admit that they were very cautious in their estimate the treatment with HIV therapy lead only to a 10% reduction in the risk of HIV transmission via injection drug use. However, they estimated that HIV therapy reduced by the risk of sexual transmission by 90% over the course of a year.
Finally, for each HIV treatment strategy the investigators calculated the quality adjusted health year (QALY) gained over a 20-year period and the number of new HIV infections prevented per treatment strategy.
Failure to increase access to HIV therapy would, it was calculated result in 64% HIV prevalence amongst injecting drug users after 20 years and 2% amongst the general St Petersburg population.
However, HIV therapy targeted at injecting drug users would prevent an estimated 40,000 new HIV infections (30,000 of which would be among individuals who did not inject drugs), adding 650,000 QALYS at a cost of $1500 per QALY gained.
Treating only HIV-positive individuals who did not inject drugs would prevent fewer than 10,000 new infections, adding 400,000 QALYs at a cost of $2500 per QALY.
The most effective and cost-effective strategy was to provide HIV therapy to both injecting drug users and individuals who did not inject drugs. This approach would, it was calculated, prevent approximately 40,000 new HIV infections, adding 950,000 QALYs at a cost of £1827 per QALY.
Sensitivity analysis performed in Barnaul yielded the same results.
“Our anaylsis indicated that expanded use of antiretroviral therapy, if appropriately implemented, could dramatically reduce HIV incidence amongst the general population in Russia, would yield enormous population-wide health benefits, and would be economically efficient”, comment the investigators.
The investigators believe that providing HIV therapy to injecting drug users is feasible. They factored additional support costs into their model to ensure that injecting drug users were properly informed and supported regarding adherence to anti-HIV therapy, and note that several studies have shown, that with appropriate support, current drug users can achieve the same levels of adherence and derive the same benefits from HIV therapy as individuals who do not inject drugs.
They conclude, “plans to expand antiretroviral therapy in St Petersburg provide for enormous public health benefits. However, if the full potential for this investment in health is to be realized, antiretroviral treatment must reach both the IDU and non-IDU populations.”
Long EF et al. Effectiveness and cost-effectiveness of strategies to expand antiretroviral therapy in St Petersburg, Russia. AIDS 20: 2207 – 2215, 2006.