Misunderstanding of questions regarding anal sex in microbicide HIV prevention trial

This article is more than 10 years old. Click here for more recent articles on this topic

There was widespread misunderstanding and misinterpretation of questions about anal sex being asked of participants in the Vaginal and Oral Interventions to Control the Epidemic (VOICE) trial, according to findings of a qualitative ancillary study to the VOICE trial qualitative analysis study (called MTN-003D or VOICE-D) presented at the HIV Research for Prevention conference (R4P) in Cape Town, South Africa last month.

“It is very important for us to know if women are having penile-anal intercourse (anal sex) in prevention trials due to the increased risk of HIV acquisition through anal sex, especially if they are using vaginal prevention products, such as microbicides,” said Zoe Duby, lead author and presenter of this study.

VOICE-D was conducted at a third of the 15 VOICE sites in South Africa, Uganda and Zimbabwe and was designed to explore the contextual and trial-specific issues affecting actual and reported product use and sexual behaviors during women's participation in VOICE. VOICE was a phase 2B, randomised, double-blind study which was designed to test the safety and efficacy to prevent HIV of daily Truvada (tenofovir 300mg plus emtricitabine 200mg) as pre-exposure prophylaxis (PrEP), daily tenofovir (300mg) as PrEP and a 1% tenofovir-containing gel to be used as a vaginal microbicide. The results of the VOICE trial found that less than a third of women were regularly using the microbicide as prescribed.



A product (such as a gel or cream) that is being tested in HIV prevention research. It could be applied topically to genital surfaces to prevent or reduce the transmission of HIV during sexual intercourse. Microbicides might also take other forms, including films, suppositories, and slow-releasing sponges or vaginal rings.


Qualitative research is used to explore and understand people’s beliefs, experiences, attitudes or behaviours. It asks questions about how and why. Qualitative research might ask questions about why people find it hard to use HIV prevention methods. It wouldn’t ask how many people use them or collect data in the form of numbers. Qualitative research methods include interviews, focus groups and participant observation.


Social attitudes that suggest that having a particular illness or being in a particular situation is something to be ashamed of. Stigma can be questioned and challenged.


How well something works (in a research study). See also ‘effectiveness’.

equivalence trial

A clinical trial which aims to demonstrate that a new treatment is no better or worse than an existing treatment. While the two drugs may have similar results in terms of virological response, the new drug may have fewer side-effects, be cheaper or have other advantages. 

Participants in the original VOICE study were asked, using Audio Computer-Assisted Self Interviewing (ACASI), how many times they had had anal sex in the past three months. It was further explained to participants that by anal sex, the question was asking about “when a man puts his penis inside your anus”. Although the use of ACASI elicits higher reporting of stigmatised behaviours, there is no opportunity to identify miscomprehension.

High reporting of anal sex at the initial VOICE study’s baseline raised concerns regarding the limitations of using ACASI. Terms for anal sex were revised and re-translated and implemented 18 months after VOICE started. This led to a decrease in reported anal sex prevalence at South African sites, for example, where overall prevalence of anal sex in the previous three months decreased form 21% to 17%.

Stage 1 of VOICE-D involved 88 women (22 women from Uganda, 26 women from Zimbabwe and 40 women from South Africa), who took part in individual one-time in-depth interviews after exiting VOICE, most of whom were interviewed before the trial's results were made publicly available. Participants were pre-selected to ensure more than 10% had reported anal sex during VOICE. Stage 1 was designed in part to better understand women’s perceptions and understanding of various risk behaviours, including anal sex, using in-depth interviews (IDI) to cover the topic of anal sex. A body-mapping activity was used to initiate discussion on sex and was used as a visual aid to provide clarity on anatomical knowledge and understanding of terms used in the interview.

Inconsistencies were found between the self-reporting of anal sex in VOICE ACASI and VOICE-D’s in-depth interviews among the 88 women. Twenty-four of 88 participants who had reported anal sex in ACASI did not disclose ever having anal sex in the in-depth interviews of VOICE-D and a third of these women needed the term for anal sex to be clarified during the in-depth interviews. Seven (of 88) reported having had anal sex in the in-depth interviews and not in ACASI, and 11 reported having had anal sex in both the in-depth interviews and ACASI.

This inconsistency may be due to a miscomprehension of ACASI questions or terms relating to anal sex, or social desirability and unwillingness to disclose anal sex behaviours to interviewers in in-depth interviews.

The widespread interpretation (in both the interview methods) of the translated terms for anal sex was for it to mean vaginal sex ‘from behind’. This could be because the widely used (formal and slang) terms for anal sex in all of the local languages (isiZulu, Shona and Luganda) are euphemistic, indirect, vague, ambiguous or could refer to both anal sex or vaginal sex, such as ‘dog-style’, ‘at the back’ or ‘from behind’. 

Body maps were used by most women to discuss pleasure, however only half of the women used the tool to identify areas associated with pain. Only six women were reluctant to discuss their sexual behaviour: two refused due to religious beliefs, one only labelled biological functions of the body, two avoided looking at the map and one woman was too uncomfortable to discuss anal sex.

Communication about sex is complex and subject to social and cultural norms. Due to taboos and social stigmatisation of anal sex, participants may not disclose openly, regardless of reporting method. It is also typically ambiguous, indirect and euphemistic. This creates challenges in sexual behaviour research where unambiguous, precise, yet understandable and socially acceptable terms, must be selected by researchers for participants to understand what is being asked of them. These challenges are amplified in cross-cultural or multi-site research, where equivalent translated terms need to be used.

It was recommended that triangulation and multi-methods, such as longitudinal in-depth interviews, ACASI and visual aids, are needed to improve validity and reliability of reporting socially stigmatised sexual behaviours. Rigorous pre-testing of terms and tools with target audience is necessary to ensure comprehensibility an accuracy of translated terms.

“We need to pay attention to the language and translation that we use. Sometimes direct and potentially uncomfortable terms may need to be used in the interest of ensuring the accuracy of the research”, said Duby.

Motivation for anal sex and gender power dynamics

The main motivations for anal sex that were revealed in the in-depth interviews involved gender and power dynamics in sexual decision-making or because of the belief that HIV cannot be transmitted through anal sex

Some of the main motivations for anal sex, according to the women, were male pleasure and male sexual satisfaction, relationship security due to the fear of losing their partner or partner infidelity, being forced, ‘accidental’ anal penetration by male partner, men wanting to have anal sex because the "anus is tighter than the vagina" and "feels like having sex with a virgin", the vagina being "too wet" and vaginal fluid being regarded negatively, to avoid contact with menstrual blood and satisfy the male partner’s sexual needs, sex workers being paid more for anal sex than vaginal sex.


See also: VOICE trial's disappointing result poses big questions for PrEP

and: Stigma, ambivalence and other priorities – explaining poor adherence to PrEP and vaginal microbicides

Duby Z et al. Language, terminology and understanding of anal sex amongst VOICE participants in Uganda, Zimbabwe and South Africa. HIV Research for Prevention Conference (HIV R4P), abstract OA02.05, Cape Town, South Africa, 2014.

To view the slides and listen to the audio of this presentation, go to:


To view the abstract, go to:


Naidoo S et al. Application of a Body Map Tool to Enhance Discussion of Sexual Behaviour in Women: Experiences from MTN 003D

To view the abstract, go to:


Duby Zet al. Perceptions and practices of heterosexual anal sex amongst VOICE participants in South Africa, Uganda and Zimbabwe. HIV Research for Prevention Conference (HIV R4P), poster P46.03, Cape Town, South Africa, 2014.

To view the poster, go to: