Rectal douching
may put men who have sex with men (MSM) at increased risk of HIV and other
sexually transmitted infections (STIs), according to research published in Sexually Transmitted Infections.
Synthesising the results of 24 separate studies, investigators showed that
rectal douching was associated with increased odds of infection with HIV and
STIs including viral hepatitis and bacterial infections such as
chlamydia and gonorrhoea.
“This is the first
systematic review and meta-analysis known to these authors to quantify
associations between rectal douching and HIV/STIs among MSM,” comment the
investigators. “High rates of co-occurring risk behaviours, including rectal
douching…highlight the need to explore high-risk practices among MSM in a
holistic way that accounts for the complex realities of the sexual risk
environment.”
The investigators
suggest that douching may damage the delicate lining of the rectum, thereby
facilitating the transmission of HIV/STIs.
Rectal douching –
the insertion of a liquid, such as tap water or soapsuds, into the rectum via a tool, to cleanse the rectum before or after
anal sex – is a common activity among MSM. Research suggests
that up to half of MSM in the US engage in rectal douching.
Studies exploring
the association between rectal douching and HIV/STI risk have yielded
conflicting results. A team of researchers at Sun Yat-sen and Shanghai Jiaotong
Universities led by Professors Huachun Zou and Yong Cai therefore performed
a systematic review and meta-analysis of studies involving MSM that examined
the relationship between douching and HIV/STI infections.
They identified a
total of 28 studies involving 21,570 MSM. Almost half (46%) were
conducted in the US, with over a third (35%) in Europe and the remainder in
South America, Asia and Africa. The studies were published between 1982 and
2018.
Half the participants (52%) reported rectal douching. There was a cross-over between
douching and high-risk sexual behaviour: 52% of men reporting rectal douching
said they had recently had anal sex without a condom and 58% reported a high number of
recent sexual partners.
Twenty studies
assessed the association between douching and HIV infection, with 17 finding a
positive association. Of the 17 studies looking at the relationship between
rectal douching and other STIs, three found that douching was associated with
increased odds of infection with hepatitis B virus, one for hepatitis C virus, six for chlamydia and
gonorrhoea, one for syphilis and two for multiple bacterial and viral STIs, while five found no association with the STIs examined.
A total of 24
studies (20,398 participants) had sufficient statistical analyses to be
included in the meta-analyses.
The odds of HIV
infection among men who practiced rectal douching were increased almost
threefold (OR = 2.8; 95% CI, 2.32-3.39), an association that remained robust
after adjustment for potential confounders (OR = 2.74; 95% CI, 2.14-3.50).
The pooled results
of the 15 studies that looked at the association between rectal douching and other STIs found that the practice was associated with a more than twofold increase
in the risk of an STI other than HIV (OR = 2.46; 95% CI, 1.95-3.11). Specifically, rectal
douching was associated with a threefold increase in the odds of infection
with hepatitis B or C, and also of chlamydia and gonorrhoea.
After taking into
account potential confounders, rectal douching remained associated with a more
than twofold increase in the odds of an STI (OR = 2.27; 95% CI, 1.70-3.04).
But was the
relationship between rectal douching and an increased risk of HIV and other
STIs simply because MSM engaging in douching were more likely to have anal sex
without a condom? The authors don’t dismiss this possibility but think it
unlikely, noting that most of the studies performed multiple analyses to take
into account potential confounders such as sexual risk behaviour and partner numbers. Findings were robust in an analysis that only included these studies.
The investigators
believe there are several reasons why the association between rectal douching
and increased HIV/STI risk is biologically plausible:
- Damage to the delicate lining
of the rectum.
- Removal of protective naturally
occurring bacteria.
- Transmission of infections
through sharing of douching tools.
The researchers
acknowledge that their research is subject to several limitations, especially
the observational design of all the studies included in the meta-analyses. They note that the studies do not record enough information about potential contributory factors, such as whether douching occurs before or after sex, the types of liquids used, and the types of tools used.
“More studies are
needed to examine co-occurring high-risk sexual behaviours among MSM who
practice rectal douching,” conclude the authors. “Our results suggest the need
for health education materials that inform MSM about the potential increased
risk of HIV/STIs if they choose to douche before or after anal sex.”