Focus on six risk factors could prevent up to 80% of HIV infections in South African women

Addressing five modifiable risk factors could significantly reduce the number of new HIV infections among South African women, according to a study published in the online edition of AIDS and Behavior.

The researchers found that six risk factors were associated with HIV seroconversion and that five of them could be addressed through prevention initiatives.

“To have a very substantial impact on HIV prevention, a range of risk factors particularly related with unsafe sex need modifying,” comment the investigators. However, socioeconomic factors, possibly related to work migration patterns, were associated with HIV seroconversion for older women.

“[The] majority of cases among women could potentially have been prevented by effective public health interventions,” write the authors.

Age was the only non-modifiable risk factor for seroconversion identified by the investigators.

HIV incidence among South African women is high and unprotected sex is the single most important risk factor for acquiring HIV in the region.

Some risk factors for HIV – such as sexual behaviour – are potentially modifiable, and researchers wanted to see the proportion of new infections that were attributable to risks that could be addressed through public health interventions.

Their study population included 2523 HIV-negative women in Durban. The women participated in three separate community-based prevention studies between 2002 and 2005.  All the women were sexually active, were regularly tested for HIV and other sexually transmitted infections, and completed questionnaires about their sexual behaviour. Information was also gathered on the women’s socioeconomic circumstances, including their partnership and employment status.

The median age was 28 (range 22 to 36) and 39% were aged 24 or under. The majority – 80% – were not employed, and 58% were either single or not living with a partner. Over two-thirds (69%) of women reported at least instances of sexual intercourse in the previous seven days. In all, 88% of women said that they consistently used condoms, but 12% of women had a sexually transmitted infection at the time of entry to the study, a further 32% were diagnosed with at least one such infection during follow-up and 22% became pregnant.

A total of 211 women seroconverted for HIV, and the overall incidence rate of the infection was 7%.

One non-modifiable risk factor – younger age – was associated with seroconversion (age under 24, p < 0.001; age 25 to 34, p = 0.017).

All the other risks associated with new infections were related to potentially modifiable risks and included:

• Single or not cohabiting, p < 0.001

• Frequency of sex (three or more acts in the previous week), p = 0.048

• Sexually transmitted infection at baseline, p = 0.0185

• Incident of sexually transmitted infection during follow-up, p < 0.001

• Pregnancy during the study, p < 0.001

• Unemployed or insufficient income, p = 0.0437.

The investigators noted that reported condom use was not identified as a risk factor. However, they write, “generally, since STIs and particularly pregnancy can only occur with unprotected sex, these two risk factors can give hard evidence of inconsistent condom use.”

Information was not gathered on the number of sex partners. But the investigators believed “being single/not cohabiting combined with high frequency of sexual acts gives strong evidence of those women having multiple partners as well as possibly engaging in transactional sex.”

Next, the investigators calculated the proportion of new infections that could be attributed to these potentially modifiable factors.

Overall, 82% of infections could potentially have been averted if modifiable risks were effectively addressed in public health and other social interventions.

Being single, not having a partner, and three or more sex acts a week accounted for 64% of new HIV infections. This increased to 71% when sexually transmitted infections were added.

Therefore, the investigators believe, “measures aimed at reducing the frequency of unprotected sex and aggressive condom counselling with couples” could have a substantial impact of HIV incidence among women.

However, the importance of individual risk factors varied according to age.

Those related to sex were responsible for 81% of infections in women aged 25 to 34. But for older women socioeconomic factors had the largest impact on incidence, with not having a job/low income the reason underlying 43% of infections.

“Improving socio-economic conditions for women along with low-risk sexual behaviours may reduce…infections considerably,” comment the investigators. They call for employers to “change labour migrating patterns whereby the family unit moves with the job holder”.

They conclude that their research provides “a robust methodology for calculating quantitative epidemiology measures of disease burden that provides policy makers and health service administrators with an important tool to prioritise health service and prevention strategies”.