After starting antiretroviral therapy, HIV-positive female sex workers in Mombasa, Kenya, increased contraceptive use by over 50% but the number of sex partners and frequency of sex did not change, R Scott McClelland and colleagues report in a fifteen-year prospective study published in advance online by the journal AIDS.
A continuing decrease in sexually transmitted infections (STIs), following initiation of antiretroviral therapy (ART), gave added support to the validity of self-reported changes in behaviour (condom use) (AOR 0.67, 95% CI: 0.44 to 1.02, P=0.06).
Improved health and wellbeing following the start of antiretroviral therapy often leads to increased sexual activity. Low amounts of plasma viral load are believed to decrease the risks of transmission. So greater access to antiretroviral therapy overtime might then affect the course of the epidemic. This consequence cannot be separated from how treatment affects sexual risk behaviour.
The findings of the few studies that have examined how treatment affects sexual risk behaviour in resource-poor setting have produced contradictory results. Findings show that unprotected sex decreased, remained the same, or in one study in the Ivory Coast, increased. These findings highlight the complexity of the issue as well as the need to develop an evidence base.
The authors of the newly-published study began their analyses with the hypothesis that ART would be associated with increased sexual risk behaviour.
An open cohort study among female sex workers (FSWs) in Mombasa, Kenya examining HIV incidence and risk factors for acquiring HIV was set up in 1993. Monthly follow-up, if desired, was available to those who tested positive.
All visits comprised a physical examination and interview that included reports on the number of sex partners, sexual contacts and sexual contacts with condoms. All received individual risk reduction education and free condoms.
In 1998 those who tested positive had CD4 cell counts performed every three months. In 2004 in accordance with national (Kenyan) guidelines all women with CD4 cell counts less than 200 cells/mm³ or an AIDS-defining illness were eligible for ART.
The analysis included all HIV- positive women with follow-up data from February 1993 until April 2008. Those women who received ART elsewhere were excluded.
Of the 898 (97%) women included in the analysis, 298 (33%) became HIV-infected after follow-up and the other 69% were positive at screening. The median number of individual follow-up visits was 10 (IQR 3-27) with the median interval between visits 33 days (IQR 29-48). 14% (129) of women began ART with a median of 24.6 (IQR 11.4-32.9) months follow-up after the start.
Over 40% of the women were using a contraceptive method in addition to a condom.
Women who started ART only differed from the other women at baseline in that they were more likely to have been married (71.3% versus 61.2% P= 0.003) to have had more children (3, IQR 2-4 versus 2, IQR 1-3; P<0.001) and were less likely to be abstinent (3.9% versus 15.9% P<0.001).
Following ART there was no evidence of increased unprotected intercourse (AOR 0.86, 95% CI 0.62-1.19) when compared with those not on ART. To the contrary an over 50% increase in consistent condom use was reported.
Among those with advanced illness (CD4 cell counts less than 200 cells/mm³) there was a significant reduction in the numbers of partners as well as frequency of sex.
The authors note that this is in line with a previous finding in this cohort that among those on ART, those with the lowest CD4 cell counts were more likely to be abstinent.
There was a non-significant decrease in abstinence (AOR 0.81, 95% CI: 0.65-1.0, P=0.07). However, the significant increase in 100% condom use (AOR 1.54, 95% CI: 1.07-2.20, P=2.02) more than compensated for this change in sexual activity, the authors argue.
The finding that incidence of STIs decreased, the authors note, eliminates the possibility of the underreporting of risky sexual behaviour.
The authors highlight the strengths of the study.
The prospective cohort design provided extensive baseline data on risk behaviour before the start of ART. The long follow-up period including a median of more than two years on ART, gave insights into how risk behaviour may change after a lengthy time on ART.
Risk reduction messages and counselling time remained constant, before and after the start of ART, so eliminating potential bias. The study’s size allowed for control of confounding factors. And, the authors add, the results support the value of looking at multiple outcomes for a comprehensive understanding of changes in sexual risk.
The authors note that previous studies have shown rapid and sustained suppression of plasma and genital HIV after the start of ART within this cohort.
They conclude that their “findings provide strong evidence that risk behaviour did not increase following ART initiation in the same cohort [within the context of ongoing risk reduction education and the provision of free condoms]. Taken together these results support the potential importance of ART as one of the tools for reducing sexual HIV transmission.”
R. Scott McClelland et al. Treatment with antiretroviral therapy is not associated with increased sexual risk behaviour in Kenyan female sex workers AIDS, advance online publication, doi: 10.1097/QAF.0b013e32833616c7, 2010.