Douching does not seem to increase STI risk

Neither rectal douching nor vaginal washing appears to be as significantly associated with sexually transmitted infections or other microbial conditions that increase the risk of HIV, as had been feared, the International Microbicides Conference heard yesterday.

In the case of women, vaginal washing and other vaginal health practices have been associated with bacterial vaginosis (BV), an imbalance in the types of bacteria that colonise the mucous surfaces of the vagina. BV can cause pelvic inflammatory disease and premature delivery in pregnant women and is associated with a higher risk of both acquiring and transmitting HIV.

The HPTN 035 trial of the candidate microbicide PRO2000 therefore included a survey of vaginal health practices, counselling against ones associated with a raised risk of BV, and assessing any link between these practices and BV. It found none, though a smaller study of women in Los Angeles did find an association not with douching, but with the use of petroleum jelly as a lubricant and BV.

In the case of rectal douching in women and gay men, there is very little we currently know about the practice. However, findings over the last couple of years that the use of lubricants for anal sex, particularly water-based ones, is associated with higher rates of sexually transmitted infections have raised concerns that other practices that impact on the fragile rectal mucosa may also raise the risk of sexually transmitted infections (STIs) and HIV. International Rectal Microbicide Advocates (IRMA) has therefore conducted a survey of rectal douching practice. Interim results were presented yesterday, although the survey is still ongoing.

Vaginal and rectal practices in women in HPTN 035 and in Los Angeles

In HPTN 035, vaginal hygiene practices were assessed at quarterly visits and the 3087 participants were counselled to try not to use the practices. They were divided into women who did not practice vaginal washing, ones who only used water, and those who used other products such as soap and water or commercial douches (Kasaro). 

The proportion of women practising any vaginal hygiene fell from 60% at baseline to 36.5% at last visit, and this was a steady fall over time, not just occurring immediately after the baseline visit.

Bacterial vaginosis was common at baseline and the proportion of women with it did not change over time – at any visit 36 to 38% of women had it. There was no association between vaginal hygiene practices and BV.

Another study of women in Los Angeles (Brown) assessed vaginal hygiene lubricant practices in an observational cohort of 141 women. The cohort was structured to reflect a mix of ethnicity and HIV serostatus: 26% had HIV and 40% were black, 34% white and 26% Latina. Their median age was 33 (range 18 to 65). Rates of anal sex were quite high: 71% had ever had it and 18% had had it over the last month.

Forty-five per cent reported vaginal douching and 4% rectal douching over the past month: the most common method was diluted vinegar in water, used by 71% of women who douched. As for sexual lubricants and similar products, 21% reported using commercial lubricants and other products such as petroleum jelly or oil over the last month vaginally, and 11% rectally.

Black women were more likely to report vaginal douching (55% reported it) and rectal lubricants (16%). They tended to favour petroleum jelly as the most often-used product whereas white and Latina women used commercial lubes more. Most women were consistent in their practices across all visits. There was no association between women's HIV status and their use of douching or lubes.

There was a strong association between use of petroleum jelly and bacterial vaginosis: averaged over all visits, women who used this were 2.6 times more likely to have BV. But there was no association between any kind of douching or with other kinds of lubricants.

Rectal douching: the IRMA survey

Shauna Stahlman of the University of California, Los Angeles, presented findings from the first three months of the IRMA rectal douching survey. During that time, 926 people answered the survey; most were gay men but 16% were women and 2% transgender. Two-thirds came from North America and 19% from Europe (7% from the UK) ,and their mean age was 38, with a quarter under 30. Over three-quarters of respondents (726) reported anal sex in the last three months and only they were included in this analysis.

Over 90% of people who had anal sex reported using lubes during the last three months and 63% reported rectal douching. Only 32% reported that their partner had always used a condom when they had been the receptive partner in anal sex.

Of the 440 people who reported rectal douching over the last three months, the vast majority (94%) were gay men – there were only 26 women reporting this. Three-quarters douched before having anal sex; about a third did it afterwards and one-fifth before and after. Three-quarters used a 'homemade product' while 35% used commercial products. 'Homemade product' usually meant water but people reported douching with things ranging from wine to urine.

Douching was associated with lube use and drug use and douchers had more sexual partners, an average of five over the last three months rather than two. It was strongly associated with having HIV: 44% of douchers had HIV compared with 18% of non-douchers. It was also associated with having an STI diagnosis: 21% of douchers reported that they had had an STI recently but only 11% of non-douchers. There was no association, however, with condom use: douchers were neither more nor less likely to use them.

In multivariate analysis, being HIV positive and recreational drug use remained strongly associated with douching, as did – to a lesser extent – age (older people were more likely to douche). But STI diagnosis was no longer significant as an independent risk factor as even though it was 43% more likely in douchers; this could be explained by the fact that they tended to have more sexual partners.

Although this is a self-selected sample and may not represent all the likely users of rectal microbicides, the survey suggests that rectal hygiene practices are already common amongst those likely to benefit from rectal microbicides and that formulation as an enema as well as a lube would probably be acceptable and not in itself likely to raise STI risk.

Future analyses will look at trends by region, gender and partners type: the survey is still open and can be participated in at www.keysurvey.com/votingmodule/s180/survey/382277/d7a7/.