ARV Treatment: Special Focus
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In the last two months, all of us who work in the field of HIV have heard the news about prevention of mother-to-child transmission. A large study in Thailand showed that transmission can be decreased by giving the drug zidovudine or AZT to pregnant women who are HIV positive. The drug is only needed in the last few weeks of pregnancy so that has made it cheaper to use. The price of zidovudine may also decrease in some countries. Is the prevention of mother-to-child transmission in Vietnam a realistic objective this year? Or in the year 2000? Is it a cost effective activity? To find out some answers to these questions, we need to look at two issues: how many cases can we prevent and what the costs are to find and prevent them. The aggregate HIV prevalence in pregnant women who were tested through sentinel surveillance in 1997 in Vietnam was 0.12%. This means about one pregnant woman in a thousand who were tested had a positive test for the virus. To imagine how few this is, think of two packages of photocopy paper sitting under your photocopy machine. Only one sheet out of these thousand sheets represents an HIV positive mother. But this aggregate figure hides large regional variations. In some southern provinces prevalence was higher, and in some northern ones it was found to be zero. Most pregnant women in most provinces were not tested at all. Let us use the aggregate figure, as it is the only one we have. There are about two million births in Vietnam this year. Simply multiplying these numbers together gives a total of 2,400 births in which the woman who delivers a baby is HIV positive. But HIV transmission from mother to child is not 'mot tram phan tram'. In Asia, only about one in four babies born to HIV positive mothers will be HIV positive. So a maximum of 2,400 divided by four or 600 babies could possibly become HIV positive. That is the maximum number of infected children that everyone in Vietnam wants to reduce. But the drug treatment is also not one hundred per cent effective. If pregnant women take zidovudine in late pregnancy, the rate of 25% transmission is reduced to under 10%. Let us use 8% as a goal. So if all the pregnant HIV positive women in Vietnam take zidovudine, then the number of HIV positive babies will still be about 200. This is the minimum number that everyone hopes to achieve. If we subtract this minimum number from the maximum one, we can see that there are only four hundred potentially preventible cases of mother to child transmission in Vietnam in 1998. What would it cost to prevent every one of these 400 infections? What are the costs of counselling pregnant women, testing them, and treating some of them? There are many kinds of 'costs' that can be considered. It is best not to consider too many complexities in this analysis, as complexities usually increase costs. Let us focus on extra financial costs to the health care system. Costs for staff doing pre-test and post-test counselling, the costs of the test kits, costs of staff to perform the testing, and the costs of zidovudine are the four main ones that we need to consider. It is easy to do the arithmetic if we want to find every single one of the six hundred pregnant women who are HIV positive. We have to test all pregnant women. That amounts to two million tests a year. We don't need to work out the exact figures for us all to agree that this much testing is unfeasible in Vietnam. The health care infrastructure in Vietnam at present cannot handle two million blood tests for any one disease in one year. So resources need to be focused. We can make some difficult targeting decisions and leave out some of the pregnant women. Let us concentrate on counselling, testing, and perhaps treating one quarter of them. In the areas with the highest prevalence. And, just for the sake of argument, let us also suppose that we are perfectly successful in our focusing and find all of the HIV positive women with only these five hundred thousand tests. Of course in reality we are going to miss some of them. What is a reasonable amount to pay for these minimum five hundred thousand tests to prevent a maximum of four hundred cases of preventible mother to child transmission in Vietnam in 1998? If each test kit costs about two dollars, then they will cost a million dollars. Ten billion dong - muoi ty dong. If we consider the staff costs of doing high quality pre and post test counselling for half a million women and quality-controlled laboratory testing by skilled technicians on half a million blood samples, the cost is much higher. At least two to three million dollars: to be more realistic let us say four million. Forty billion dong. So when we divide the 400 infections prevented and lives saved by the cost of 4 million dollars, we find that it will cost $10,000 dollars to prevent one infection. Even if we focus more narrowly and test just one in ten pregnant women and our targeting is absolutely perfect, it still costs $1,000 to prevent just one end point infection. Imagine that the cost of a condom is two hundred dong, represented by a single sheet of paper. The cost of ten thousand dollars to prevent one infection is a pile of paper thirty metres high. If our targeting is absolutely perfect, one thousand dollars to prevent an infection still represents a pile of paper as high as a basketball net. Even if all our above assumptions are wildly inaccurate, it certainly costs over a thousand dollars to prevent one infection. It is clear that a prevention strategy of mass testing of pregnant women in Vietnam is NOT cost effective at present. Who can afford the millions of dollars this year to prevent just four hundred potential infections, who can afford it next year, and who can afford the massive investment in human resource training in counselling, testing, and programme management? As Joseph Saba, Clinical Research Specialist in the Department of Policy, Strategy, and Research of UNAIDS Geneva notes: "We modeled the cost effectiveness," (of mass testing and counselling) "and if the prevalence rate is very low, then maybe one should not use a program of mass testing and counseling, but either target settings where prevalence is higher, or focus testing on those women known to be exposed to HIV in one way or another." Even in the areas of the Vietnam where prevalence is highest, it is still very low. So we can only focus on the sexual partners of men who are known to be living with HIV. The drug costs are not a big problem. Money can be found for drugs to treat six hundred women if they are found. Even a donation of zidovudine would cost the transnational drug company Glaxo Wellcome almost nothing: a maximum of thirty thousand dollars at today's prices. And probably much less. Drug costs are no longer the major constraint. When the seroprevalence of HIV infection among pregnant women in Vietnam has increased twenty fold or thirty fold to two percent or three per cent, then it is time to discuss the issue of mass testing as a prevention strategy again. Studies in Africa show that when the prevalence is over two per cent, it is time to begin training. High volume testing does not save much money. Even when HIV prevalence in pregnant women reaches an overwhelming 12%, it still costs $1000 to prevent just one infection. Until then let us put most of our efforts into preventing youth and adult infections. HIV infected infants and children never spread HIV. Sexually active people do. If we prevent one infection in an adult, chances are we will prevent many more infections that they will cause down the line. Jamie Uhrig Hanoi - May 1998 |
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