prenatal care, provider behavior, or other factors affecting perinatal HIV transmission are not optimal, the number of HIV-infected babies increases. For the purposes of this illustration, the committee's assumptions about current practices are as follows: 85% of HIV-infected women seek prenatal care, 75% of women are counseled regarding HIV testing, 80% of women accept the test, 90% of HIV-infected women are offered ZDV, and 90% of women accept and comply with ZDV treatment when it is offered. Given this scenario, 1,172 babies would be born to the hypothetical cohort of 7,000 HIV-infected women, a 235% increase over the currently achievable state (i.e., from 350 to 1,172 HIV-infected babies).4

If we hold all but one condition constant, changing one parameter at a time, the impact of changes in the current environment can be assessed (for details, see Appendix K):

  • Increasing receipt of prenatal care from 85% to 100% reduces the number of HIV-infected babies by 9% (i.e., from 1,172 to 1,070).
  • Increasing the rate at which providers' offer HIV tests from 75% to 100% reduces the number of HIV-infected babies by 16% (i.e., from 1,172 to 979).
  • Increasing women's acceptance of HIV tests from 80% to 100% reduces the number of HIV-infected babies by 12% (i.e., from 1,172 to 1,027).
  • Increasing providers' offering of ZDV treatment from 90% to 100% reduces the number of HIV-infected babies by 5% (from 1,172 to 1,107).
  • Increasing women's acceptance of ZDV treatment from 90% to 100% reduces the number of HIV-infected babies by 5% (i.e., from 1,172 to 1,107).

Given the current environment, the most effective single intervention to reduce perinatal transmission is to increase providers' offering of HIV tests (reduces perinatal HIV transmission by 16%). If providers were in complete compliance with the PHS guidelines (i.e., they offered HIV tests and ZDV treatment to all women), there would be a 24% decrease in the number of HIV-infected babies (from 1,172 to 893). Alternatively, if the current environment remained the same, but all HIV-infected women accepted HIV testing when offered, and accepted and complied with ZDV treatment, there would be a 19% reduction in the number of HIV-infected babies (i.e., from 1,172 to 947). If both providers and HIV-infected women had optimal rates (i.e., if all but prenatal care is set to 100%), there would be a 52% decline in the number of HIV-infected babies (i.e., from 1,172 to 560). Increasing the rate at which providers offer HIV tests from 75% to 100%, and increasing the proportion of women who accept it from 80% to 100%,

4  

The model assumes only two HIV transmission rates, 0.25 if women are not treated and 0.05 if they are treated. These transmission rates actually vary according to the HIV-infected woman's clinical state, and the onset and completeness of treatment. The model also assumes that testing rates for HIV-positive women are similar to those observed in the general population of pregnant women.



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