Extended ART cost-effective for preventing mother-to-child HIV transmission in Nigeria

The World Health Organization’s (WHO) new recommendation for the extended use of triple drug antiretroviral prophylaxis for mother and infant is highly cost-effective compared to the current short-course two drug therapy for the prevention of mother-to-child transmission (PMTCT) in Nigeria, Maunank Shah and colleagues reported in an analysis published in the advance online April edition of AIDS.

Scaling up the current 10% PMTCT service coverage to the existing antenatal coverage of 58% the WHO’s recommendations would reduce mother-to-child transmission to 12.8% per year, compared to 16.1% with the current minimum standard of care.

7680 cases of infant HIV and 230,400 disability-adjusted life years (DALYs) each year would be averted. (DALYs refers to the number of years of life saved in the Nigerian context, assuming that HIV infection is prevented).

This represents an incremental cost-effectiveness ratio (ICER) of US$113 for each DALY averted. (Incremental cost-effectiveness ratio represents the difference in cost between using the existing intervention and the new intervention). This is highly cost-effective according to a WHO recommended willingness-to-pay threshold, which classifies any intervention that costs less than 1 x GDP per capita as highly cost-effective. (GDP per capita was US$1191 in Nigeria in 2010).

PMTCT in Nigeria is an important public health strategy and priority. An estimated 4-12% of pregnant women are HIV-infected. Without any intervention MTCT rates are approximately 30-45%. An estimated 67,000 to 125,000 children are infected through MTCT each year. In 2009 240,000 children were reported to be living with HIV.

The current minimum standard of care comprises single-dose nevirapine (the least effective of ARV prevention strategies) or short-course combination ARV (zidovudine + lamivudine), which while more effective does not provide any benefit to the mother for her own health. 

New evidence led to WHO’s new recommendations for extended ART for mothers and and extended prophylaxis for infants. This strategy could reduce transmission to 1-2% but is anticipated to be considerably more expensive than current strategies in Nigeria.

In light of Nigeria’s plans to scale up PMTCT programmes at the national level, the authors wanted to determine whether WHO’s recommendations are a cost-effective policy choice compared to the current short-course ART strategy in reducing mother-to-child transmission.

The analysis was done from a health system perspective with a target population of HIV-infected pregnant women in Nigeria and a target audience that included the Ministry of Health and public-sector health-care payers.

A decision-analysis model compared two strategies for PMTCT programme coverage:

1) The WHO new recommendation, Option B: extended maternal triple ART (zidovudine (AZT)/lamivudine (3TC)/efavirenz(EFV) starting at 14 weeks of pregnancy continued throughout breastfeeding with infant antiretroviral prophylaxis, and

2) Minimum standard of care in Nigeria: short-course ART (AZT/3TC) from the 34^th week of the pregnancy to one week after delivery with single-dose nevirapine for the infant and mother during labour/delivery.

The primary outcomes were expected costs, paediatric HIV cases and total DALYs with each strategy. Incremental cost effectiveness ratios (ICERs) determined cost-effectiveness; that is the cost in US dollars for DALYs averted and the cost in US dollars for the number of HIV cases prevented when comparing the two strategies.

The authors note that from a health system perspective WHO’s  recommendation could potentially be cost-saving assuming the lifetime health costs for an HIV-infected child increased to more than US$17,000, or if MTCT rates were to exceed 20%.

Estimated costs if coverage were extended to current pregnancy rates using the WHO recommendation or the minimum standard of care would be US$48 million a year, and $10.5 million a year, respectively. While considerable funding is received from PEPFAR and the Global Fund for HIV/AIDS services, a 2010 audit showed US$5.8 million was spent on PMTCT services. 

The average health system cost for each pregnancy using the WHO recommendation and the MSOC would be US$401 and US$293, respectively.

The authors note maintaining coverage at the current level of 10% using the MSOC would cost the Nigerian health system approximately US$93,000,000 a year resulting in the most expensive and least cost-effective choice. Offering the WHO recommendation at 100% coverage would cost the same.

The study authors noted a number of limitations, including difficulties in estimating lifetime treatment costs for an HIV-infected child, the lack of inclusion of any health care costs averted as a result of maternal treatment, and an assumption that uptake of voluntary counselling and testing, as well as PMTCT interventions, would be high among Nigerian women.

However they say that their model can help guide scale-up plans by demonstrating the potential cost-effectiveness of different levels of coverage, allowing informed decision-making about how to allocate scarce resources.

The authors note cost-effectiveness is dependent upon the lifetime costs of caring for infants infected perinatally and the efficacy of ARV regimens and add “Despite potential variability in these parameters sensitivity analysis suggests an almost 100% chance that the WHO recommendation…is the preferred [and most cost-effective] option for PMTCT.”

Shah M et al. Cost-effectiveness of new WHO recommendations for prevention of mother-to-child transmission of HIV in Nigeria. AIDS, 25: 1093-1102, 2010. (View free abstract here).