Study raises questions about cost effectiveness of nevirapine regimen
Polly Clayden, HIV i-Base
A cost effectiveness analysis published in the 20 August 2004 edition of AIDS reports that the efficacy of the nevirapine regimen for reducing mother-to child transmission in a field setting is much lower than desired and despite the low cost of the drug itself requires significant financial resources to implement successfully.
The authors explain that the United Nations (UN) agencies recommend a four-component strategy for reducing HIV-infection in children:
- HIV prevention particularly in young women;
- Prevention of unintended pregnancy in HIV-infected women;
- Reduction of MTCT through interventions with antiretroviral drugs, safer delivery and infant feeding;
- Care, treatment and support to HIV-infected women, their infants and their families.
However, the third component, particularly the use of antiretroviral drugs, has dominated the focus of donors and researchers in the MTCT field. Although in the developed world, use of effective interventions has meant that MTCT has been virtually eliminated, in developing countries interventions have been difficult to implement due to high costs and lack of healthcare infrastructure. Single-dose nevirapine to the mother and a single dose to the infant – according to the HIVNET 012 results published in 1999 – have been the most widely discussed strategy. The authors also emphasise that although in a trial setting this intervention has been shown to reduce MTCT by approximately 47%, for very little cost, in a field setting clinics frequently need additional financial and technical resources to implement the protocol. “Thus, the benefits of low cost and simplicity of the intervention may not always be realised in practice,” they write.
Additionally they explain that less attention has been given to the other components of the UN strategy and funds are primarily being dedicated to this single intervention. The study examines these issues by modeling the cost-effectiveness of single-dose nevirapine interventions for HIV-infected women and their infants using field data from eight sub-Saharan African countries. National programme costs and impact on infant infections, and reductions in adult HIV prevalence and unplanned pregnancies among HIV-infected women that would have equivalent impact on infant infections prevented by the nevirapine are analysed. The model outcomes include total national programme costs, the number of infant infections averted, the cost per HIV infection averted, and the cost per disability adjusted life year (DALY) saved by the intervention.
The primary research question was: “What are the health benefits for national health care systems to invest in a short-course nevirapine intervention for HIV infected pregnant women, and what reduction in adult HIV prevalence and reduction in the number of HIV-infected women who become pregnant, would yield equivalent reductions in infant HIV transmission as the nevirapine intervention.”
Data from antenatal clinics from Botswana, Cote D’Ivoire, Kenya, Rwanda, Tanzania, Uganda, Zambia and Zimbabwe were used. These countries were selected because they have high HIV prevalence among pregnant women and great differences in uptake of the various stages involved in accessing the nevirapine intervention. The investigators report wide variation in cost outcomes across countries.
Base-case cost effectiveness results
In this analysis the average national programme costs for the intervention were $3,646,703, this ranged from $439,537 in Botswana to $6,679,675 in Uganda. The average cost per HIV infection averted was $3,813, ranging from $1,808 in Botswana to $9,258 in Cote d’Ivoire. The cost per DALY saved ranged from $58 in Botswana to $310 in Cote d’Ivoire. They noted that healthcare systems accounted for most programme expenses, followed by HIV testing and counselling but drug costs accounted for a very small proportion of the overall costs. Besides the very low cost of the drug, this also reflected the low numbers of eligible women taking up all the interventions and in turn receiving the nevirapine.
Impact of HIV prevalence and unplanned pregnancy
They report that lowering HIV prevalence by just a small amount among women of childbearing age would have an equivalent impact to the nevirapine intervention in reducing infant infection. In Cote d’Ivoire, prevalence would only need to be reduced by 1% from 10% to 9% and in Botswana – where the most cost effective nevirapine intervention was found – a reduction from 43% to 39% would be necessary to produce an equivalent reduction.
Similarly, a minimal reduction in unplanned pregnancies in HIV-positive women would lower the rate of infant infection by the same rate as the nevirapine intervention. The authors cite Kenya and Zambia, lowering the pregnancy rate by 5.6% and 6.6% respectively would have the equivalent impact. In countries where the nevirapine intervention was more cost effective such as Rwanda a greater reduction would be needed, in this case by 35% to achieve the same reduction in infant infection.
Cost effectiveness of more effective regimens
In this study, a sensitivity analysis determined that cost-effectiveness of the nevirapine intervention was highly sensitive to the effectiveness of the regimen. The amount of money that would be equivalent to the nevirapine intervention was calculated as cost per DALY saved, this could then be spent on alternative peri or postnatal regimens or strategies. The model uses a drug cost of $0.27 for the nevirapine and an effectiveness rate of 47% in reduction of mother to child transmission.
The authors explain that it has been suggested that more costly antiretroviral regimens are either unaffordable or not cost effective in most developing countries. Compared to the across country base-case analysis in this evaluation, however, they report that $152 could be spent per pregnant woman to maintain an equivalently cost effective programme to the nevirapine intervention if the efficacy of that intervention were 70%.
The greatest expense
Overall, this analysis found that the greatest expense in scaling up antiretroviral programmes to reduce mother to child transmission will be the cost of building up the healthcare system to implement them successfully. The authors believe that earlier analysis of the cost-effectiveness of these programmes have either not accounted for or underestimated the limitations of current healthcare systems in Africa. The estimated cost per DALY saved of a mean of $127 across all eight African counties evaluated far exceeds earlier published estimates of $11.29.
They point out though that overall this intervention should be considered cost effective, although variable across countries and less so than previously reported. The finding that programmes could spend up to $152 per woman on an antiretroviral drug that had 70% efficacy and achieve the same cost effectiveness as the current nevirapine programmes is important, and the authors add: “Therefore spending more on the eligible women who actually make it through the system and receive the antiretroviral drug would be more efficient and effective.”
Sweat M, O’Reilly KR, Schmid GP et al. Cost-effectiveness of nevirapine to prevent mother-to-child HIV transmission in eight African countries. AIDS: Volume 18(12) 20 August 2004 pp 1661-1671.