Polly Clayden, HIV i-Base
There are limited data from programmes in resource-limited settings describing the effectiveness of HAART compared to AZT monotherapy for PMTCT.
Scott Dryden-Peterson and colleagues from Botswana showed findings from a prospective, observational study of infants, born to HIV-positive mothers, enrolled on the maternity wards of one urban and one rural hospital between February 2009 and April 2010.
The investigators followed the infants from birth to 6 months and compared transmission rates between infants born to mothers receiving either HAART or an AZT based PMTCT strategy. Infants were tested for HIV (DNA PCR) at 1 month of age.
In Botswana, in accordance with national guidelines, the PMTCT programme provided HAART for women with CD4 <250 cells/mm3 and AZT monotherapy from 28 weeks gestation for women with CD4 >250 cells/mm3 (with single-dose NVP if <4 weeks AZT received). Infants were given single dose NVP+ one month AZT.
A total of 423 mothers agreed to participate and had received either HAART or AZT. Out of 428 infants, 258 were born to mothers receiving HAART and 170 to those receiving AZT (with or without single dose NVP).
Mothers receiving HAART had a longer duration of antiretrovirals prior to delivery, median 12 weeks (IQR 7.1-17.7) compared to median 10.4 weeks (IQR 7.8-12.1) for those receiving AZT, p=0.001.
The median CD4 count was lower for women receiving HAART compared to AZT, respectively 262 vs 430 cells/mm3, p<0.001.
There were no significant differences in infant prophylaxis, infant feeding or prematurity between the two groups.
Overall 10 infants (2.5%) were HIV-infected, 9/158 (5.7%) in the AZT group and 1/249 (0.4%) in the HAART group, p=0.001. When the investigators restricted the AZT group to mothers with CD4 >350 cells/mm3, as recommended in WHO guidelines, their findings were similar, p=0.007. They noted that half the infections occurred among mothers with >350 cells/mm3.
In multivariate analysis, the adjusted risk ratio for AZT compared to HAART was RR 15(95% CI 2.1-109), p=0.008.
The investigators acknowledged that they were unable to determine HIV status for 21 (4.9%) infants, including 9 who died prior to testing. Also, they were unable to determine efficacy in protection during breastfeeding as few women opted to do so in this programme.
However they wrote: Strategies to provide HAART for all pregnant women, as currently underway in Botswana, could nearly eliminate MTCT.
PROMISE will also more definitively address the AZT vs HAART debate for women who do not presently require therapy for their own health. In the Kesho Bora study with randomised comparison of women with similar CD4 200-500 cells/mm3, the transmission rate in women who received AZT vs those who received HAART was not significantly different. 
However real life is not always like a trial and notably in this analysis women with lower CD4 counts receiving HAART had better transmission rates than healthier women with AZT. That PMTCT strategies are complicated from an operational point of view has been a big concern among implementers.
If the differences between the groups are as great as appear to be in the retrospective analysis in the Botswana report, again PROMISE will then end early as there will be interim DSMB reviews of the data.
- Dryden-Peterson S et al. Effectiveness of Maternal HAART vs ZDV to Prevent MTCT in a Programmatic Setting: Botswana. 18th CROI. Boston. February 2011. Poster abstract 740.
- de Vincenzi I et al. Triple-antiretroviral (ARV) prophylaxis during pregnancy and breastfeeding compared to short-ARV prophylaxis to prevent mother-to-child transmission of HIV-1 (MTCT): the Kesho Bora randomized controlled clinical trial in five sites in Burkina Faso, Kenya and South Africa. 5th IAS Conference, Cape Town, South Africa.19-22 July 2009. Abstract LBPECO1.