Five years after the ending of one of the three big
randomised controlled trials of male circumcision as an HIV prevention measure,
four out of five men who were in the control arm of the trial and thus not
circumcised have opted to get circumcised, a follow-up study presented to the 18th Conference on Retroviruses and Opportunistic Infections has found.
The study also found that, if anything, the protective
effect ascribed to circumcision appears to have strengthened over time.
The post-trial analysis was conducted on the randomised
controlled trial of male circumcision as an HIV prevention measure conducted in
Rakai, Uganda, in 2005-6 (Gray 2007). In this study 4996 HIV-negative men aged 15 to 49 were
randomised either to be immediately circumcised or to be offered circumcision
at the end of the trial.
The study was designed to last two years but was terminated
early in December 2006 when it was found that HIV infections were just
under half as common (efficacy, 51%) in men who had been randomised to be
circumcised compared with men in the control group.
analyses showed that this efficacy underestimated the true effectiveness of
circumcision. The HIV infection rate in men who actually got circumcised was
58-60% lower than in men who remained uncircumcised, and 70% lower in men with
high numbers of partners.
Dr Xiangrong Kong of Johns Hopkins University told the conference in Boston that by the end of the fifth
year after the study ended just over 80% of the control group, who had not been
circumcised during the trial, had opted for circumcision and, out of 2916 men who were uncircumcised at the last scheduled visit during the trial, only 372 men
now remained uncircumcised. Including the intervention group and excluding those lost to follow-up, 90% of those who entered the study had been circumcised.
Looking at men who were not circumcised during the trial, HIV incidence in men who got
circumcised, in the post-trial period was one infection per 181 men per year after circumcision (0.55%), and in men who remained uncircumcised one infection per 60
men a year (1.67%). Circumcision was thus 68% effective. If the trial period was included
this made very little difference and efficacy still stood at 67%.
If the men who got circumcised during the trial were included, then the overall efficacy of circumcision over the whole period from the start of the study was 73%.
There are data on sexual behaviour for the first 2.8 years
since the end of the trial. Before the trial, there had been concerns that
circumcision might produce behavioural disinhibition in men and an increase in
unsafe sex, especially once men knew circumcision worked.
In the original trial, 18% of participants reported
consistent condom use during the trial and 52% did not use them at all. During
the follow-up period, condom use declined by 4.3% in consistent condom users to
13.5% and the proportion who never used them increased by 6% to 58.2%.
there was no difference in decreases in condom use between circumcised and
uncircumcised men, and in fact condom use levels now are almost exactly what
they were at baseline before the start of the study. The declines in condom use
therefore probably reflect reduced availability of condoms and safer sex advice post-trial, rather than any disinhibiting effect of circumcision.
There was no change in the number
of non-marital sexual partners, and a 9.4% decrease in the number of men who
reported alcohol use during sex, again with no difference between circumcised
and uncircumcised men.
These findings are remarkably similar to a post-trial
analysis 3.5 years after the end of one of the other two circumcision efficacy trials, in Kisumu,
Kenya, presented at the 2008 International AIDS Conference, which found a long-term
efficacy of 65% for circumcision and no increase in risk behaviour.