NOTE: all abstract citations are from the XI International Conference on AIDS, held in Vancouver, BC, July 7-12, 1996.
An Ounce of Prevention or a Pound of Cure?
An important context for a discussion of perinatal HIV transmission (PHT) prevention strategies is the economic framework into which any strategy must fit. This "real-world" concern is perhaps most pressing in developing countries. At the XI International AIDS Conference in Vancouver, BC, in July 1996, studies which sought to evaluate the costs and savings of PHT prevention strategies were presented from a variety of global perspectives.
Cost-Effectiveness of PHT Interventions in Developing Countries
PHT is a particular problem in Africa, where both HIV seroprevalence and PHT rates are high. Within the existing economic structure, there are additional problems of limited health care, quality and access which affect the feasibility of PHT prevention programs in this region. Researchers from the U.S. Centers for Disease Control and Prevention (CDC) presented results from a study of the cost-effectiveness of AZT prophylaxis in developing countries. This study involved the creation of a "decision model" that encompassed potential epidemiological effects, cost and cost-effectiveness of a national AZT program for pregnant women in Cote d'Ivoire and in Thailand. The short-course regimen evaluated in the program would give AZT in the last 4-6 weeks of pregnancy, and then during labor and delivery to the mother only.
The researchers compared the costs, cost-savings and cost-effectiveness of short-course AZT with those incurred with no intervention. Two economic perspectives were examined: the cost to the healthcare system and the cost to society, where an arguably broader economic impact may be seen. Looking at the cost per case prevented requires acknowledging that an intervention can still represent a savings, even if there is a net cost. This is different from a cost/benefit analysis in that there may not be a cost-savings but there may be cost-effectiveness.
The model was designed to consider program costs, lifetime HIV-related healthcare costs and lost productivity costs associated with childhood HIV infection. Costs were reported in 1994 U.S. dollars, and future costs were discounted at 5%. The primary outcome measure was cost per case of infant HIV infection prevented. The results were sensitive to theoretically possible changes in maternal seroprevalence, AZT efficacy and lost productivity costs. In short, this model allowed the researchers to estimate that a national AZT program would reduce perinatal HIV incidence by 12% (combined for both countries).
Although the start-up costs for the programs are large -- $13.3 million in Cote d'Ivoire and $21 million in Thailand -- there would be significant overall savings to society and to national workforce productivity for both countries. Cost may be otherwise evaluated in terms of cost per pregnant woman: the cost in Cote d'Ivoire is $19.85 and in Thailand, $16.80. The cost to the healthcare system per infant HIV case averted in Cote d'Ivoire is $3,655 and in Thailand, $8,612. When productivity is also considered, the program savings per infant case averted ranges from $8,255 in Cote d'Ivoire to $27,200 in Thailand. In conclusion, short-course AZT is expected to save lives and may be cost-effective (ThC413).
Another research group presented a cost-effectiveness perspective on several interventions under study for use in developing countries. Although the efficacy of these strategies has not been established, the economic determinations made in this preliminary analysis are valid and useful.
The researchers evaluated several interventions: 1) the 076 regimen, 2) a shortened AZT regimen, 3) AZT administration during labor only, 4) elective cesarean section, 5) formula-feeding (alone and in combination with the first 4 strategies), 6) vaginal cleansing/disinfection and 7) vitamin A supplementation. For each intervention, they examined cost, health effects (in "disability adjusted life years"), and cost-effectiveness, given "plausible values" of HIV seroprevalence in a locale, efficacy of the intervention, compliance from patients and providers with the intervention, and coverage.
Despite the multiplicity of factors and variables that go into this analysis, the results may be summarized fairly simply.
The cost-effectiveness of these interventions were all found to compare favorably with existing child survival interventions in developing countries. Which intervention emerged as most cost-effective varied with HIV prevalence (e.g., 5%, 10%, 20%). Overall, the higher effectiveness of a shortened AZT regimen combined with formula-feeding "offsets the higher coverage and lower cost of simpler interventions such as vaginal cleansing and AZT administration during labor." The investigators conclude that "field research to confirm these encouraging findings and policies to implement effective programs to prevent perinatal HIV transmission deserve high priority in developing countries" (ThC4822).
The Cost-Effectiveness of Preventing PHT in North America
One interesting U.S. study compared the cost-effectiveness of 3 screening strategies to prevent PHT: 1) offering testing to pregnant women determined to be at risk, 2) universal HIV counseling of all pregnant women, with voluntary HIV testing and 3) "compulsory screening," which seems to mean mandatory testing. The researchers found that screening women with identified risk factors (the method studied in arm 1) was least costly as well as least effective, failing to identify 75% of pediatric infections detected by either of the other 2 methods. They also concluded that, in this strictly controlled clinical trial setting, compulsory screening (arm 3) appears to be better than voluntary screening at identifying cases of HIV infection. But, the researchers continue, this compulsory strategy may be suboptimal if implemented in the real world, where many women may delay or altogether avoid seeking prenatal care, or may refuse treatment even if their HIV positive status were identified through such an approach. Therefore, they say, the "potential behavioral effects of compulsory screening may negate these [beneficial] effects." As the debate rages over what policies would best prevent perinatal HIV transmission, consideration must be given to the psychological and emotional factors that may not be addressed in the clinical trial setting but which provide a very real context for any intervention in the real world. These factors and human rights in general, as well as cost-effectiveness, must be addressed (WeC3590).
A clear and compelling study from the CDC offers "strong support for implementing U.S. Public Health Service (USPHS) recommendations," i.e., counseling and voluntary HIV testing and treatment with AZT of HIV-infected pregnant women and their infants. CDC researchers calculated the national costs of implementing these guidelines, and compared the costs with the cost-savings gained by preventing new pediatric infections. They used the 076 regimen and results in their analysis.
Without any intervention, an estimated 1 of 4 HIV positive women in the U.S. will perinatally transmit HIV. This means 1,750 HIV positive infants born each year, with lifetime estimated medical costs of $282 million. The estimated cost of the intervention (counseling, testing and AZT) is $67.6 million. The estimated number of annual (infant) infections prevented is 656, representing a savings of $105.6 million in medical care costs. The net savings, then, is $38.1 million. This estimate excludes lifetime productivity savings and quality of life improvements related to HIV infections averted.
Finally, a Canadian study concluded that using AZT during pregnancy successfully prevents PHT, saves lives and is cost-effective. They based their conclusions on an evaluation of the economic impact of implementing the 076 regimen in their hospital in Montreal. Since 1991, 116 HIV positive women have given birth there. Their overall PHT rate is approximately 25%, ranging from about 31% among untreated women to 7.6% among AZT-treated women. In comparing the costs of treating vs not treating, the researchers assessed all costs that might be incurred by the hospital, including ambulatory (outpatient) and hospitalized (inpatient) services.
At Ste-Justine Hospital, the full 076 regimen costs $2,000 (Canadian) per mother/child pair. The total hospital costs per year for an asymptomatic HIV-infected child are $19,520; for an ill HIV-infected child, $36,187, and for affected but non-infected children, $7,258.
The researchers found that, over a period of 3 years, treatment with AZT prevented 2 of 3 cases of PHT and reduced management costs by 47% (ThC4807).
Conclusion
It would appear that the old saying may be true, that an ounce of prevention really is worth a pound of cure. With respect to the slogan of the conference, "One World, One Hope," the importance of continual efforts to assure that global resources are used wisely and responsibly is clearer than ever. It will take concerted humanitarian action to ensure that the official slogan rings truer than the more cynical one coined by AIDS activists at the conference, who quipped, "Whose World, Whose Hope?" See also Perinatal HIV Transmission in the Era of 076: Updates from the XI International Conference on AIDS in Vancouver, BC
Leslie Hanna is Associate Editor of BETA.