Women who learn of their HIV infection during pregnancy are at higher risk of vertical transmission of HIV than those who previously knew their status, according to a matched case-control study of Ministry of Health facilities in Nyanza province in Kenya. The study also found that health system factors had a much stronger impact on vertical transmission of HIV than psychosocial factors.
The HIV prevalence of pregnant women is 19.1% in Kenya. Despite a 90% coverage of prevention of mother-to-child (PMTCT) services in Kenya, the country's rate of vertical transmission is 16%. A study which aimed to determine the individual, sociocultural and health-system factors which contribute to PMTCT failure in Kenya, was presented by Maricianah Onono at the International Conference on AIDS and STIs in Africa (ICASA), held in Cape Town, South Africa, from 7 to 11 December 2013.
Two hundred participants were enrolled in the case-control study as infants were diagnosed with HIV from November 2012 to June 2013. Fifty cases of HIV-infected mothers of infants aged six weeks to six months with a definitive diagnosis of HIV were enrolled, along with 150 controls of HIV-infected mothers of infants in the same age groups, who were not HIV infected. Cases and controls were matched in a 1:3 ratio based on sociodemographic characteristics and type of health facility.
Vertical transmission of HIV was 2.85 times more likely in mothers who learnt their HIV status during the course of pregnancy (95%CI, 1.40 - 5.77). Women who had not adhered to ART for their own health or for PMTCT were 3.35 times more likely to give birth to an HIV-infected infant (95% CI, 1.48 - 7.58). Infants born through home delivery were 2.40 times more likely to be HIV infected (95% CI 1.01 - 5.80).
Infants who had not been administered ART for PMTCT consistently in an adherent manner were also 3.92 more likely to be HIV infected (95% CI, 1.13 - 13.58). In cases where infants were not given ART prophylaxis, even when dispensed at the facility, the infants were 9.71 times more likely to acquire HIV, although the 95% confidence interval for this result is very wide at 2.74 to 34.57.
Facility-related factors which resulted in vertical transmission of HIV to infants included mothers not receiving HIV education (OR=3.57; 95% CI, 1.36 - 9.33); mothers not receiving HIV counselling (OR = 3.35; 95% CI, 1.28 - 12.21); women not being encouraged to involve their male partners (OR = 3.87; 95% CI 1.25 - 11.99); and women not receiving disclosure assistance (OR = 5.63; 95% CI, 1.99 - 15.9).
Other facility-related factors that increased the risk of HIV transmission to infants were: not being given ART at the first contact in the clinic (OR=2.97; 95% CI, 1.38 - 6.31); and health providers not following guidelines for the prescription of ART for mothers (OR = 8.61; 95% CI, 2.83 - 26.15) or for infants (OR = 9.72; 95% CI, 2.75 - 34.37). Factors such as accessibility and cost of health-facility services were not significantly associated with vertical HIV transmission.
Psychosocial factors such as disclosure of HIV status to close family members, stigma experienced from the community or facility, and intimate partner violence were not found to be statistically significant factors. However, mothers who lacked any social support were 2.83 times more likely to bear an HIV-infected infant (95% CI, 1.12 - 7.15).
There was no statistically significant difference in the mother’s mean age (26 years), infant’s mean age (3.9 months) and maternal CD4 counts (521 cells/mm3, IQR:354-671 in cases; 559 cells/mm3, IQR: 361-747) between cases and controls.
Women already on ART entering PMTCT programmes
Women entering antenatal care already on ART comprise a growing proportion of all women entering PMTCT programmes, according to a study presented at ICASA by Landon Myer of the University of Cape Town.
The study examined the clinic folders and PMTCT registers of pregnant women making their first antenatal visit to the Gugulethu Midwife Obstetric Units (MOUs). Gugulethu is a township outside Cape Town, South Africa, with a single large primary care antenatal and obstetric unit where approximately 4800 pregnant women are seen per year, 29.16 % (approximately 1400) of whom are HIV infected. A total of 17,683 women made a first antenatal care visit between 1 January 2010 and 31 March 2013, 27 % (4739) of whom were HIV positive.
The proportion of HIV-infected women entering antenatal care already on ART increased from 4.7% in the first quarter of 2010 to 34.7% by the first quarter of 2013, a relative increase of 600%. According to these results, by 2017, more than 50% of all HIV-infected pregnant women entering PMTCT services will already be on ART in this setting.
PMTCT programmes do not traditionally focus on HIV-positive women who are already using ART. PMTCT programmes are traditionally focused on identifying HIV-positive pregnant women, identifying those that need ART and delivering interventions to those who do not already know their HIV status.
“There is an urgent need to understand the optimal approach to manage these women in terms of individual patient management and at the health systems level. This may require different approaches than those used previously in PMTCT programmes,” said Dr Myer.
He highlighted a number of differences in the management of women already on ART that need to be incorporated in the planning and delivery of PMTCT services as the proportion of women already taking ART at the time of conception grows in the future. These include:
- The importance of viral load testing to ensure that women already on ART have fully suppressed viral load during pregnancy and at the time of delivery.
- Adherence support during pregnancy is necessary in order to maintain viral suppression.
- The importance of retention in both long-term HIV care and in maternal-child health services where prevention of mother to child transmission is the primary focus.
Onono M et al. PMTCT failure: The role of maternal and facility-related factors. 17th International Conference on AIDS and STIs in Africa, Cape Town, abstract ADS067, 2013.
Myer L et al. Increasing proportion of HIV-infected women entering PMTCT already on antiretroviral therapy: Implications for PMTCT programmes. 17th International Conference on AIDS and STIs in Africa, Cape Town, abstract ADS068, 2013.