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.