Researchers in San
Francisco wished to measure the impact of providing
risk reduction counselling to people taking post-exposure prophylaxis (PEP) to
prevent HIV infection. They measured changes in sexual behaviour one year later.
They randomised 457 people receiving PEP to either receive two
sessions of standard counselling, or an enhanced programme of five counselling sessions.
The standard counselling intervention consisted of two
sessions of 20 to 30 minutes each, individually tailored on the basis of social
cognitive theory, motivational interviewing, and coping effectiveness training. In the first session, the counsellor and
participant explored the details and context of the risk exposure and developed
a written risk reduction plan. At the second session a week later, the baseline HIV test
result was given. The participant was asked about risk behaviour in the past
week and the effectiveness of the risk reduction plan, which was adjusted if
People receiving the enhanced intervention received the same
two sessions, as well as three further sessions, during which difficulties in
implementing the plan were explored, contextual factors (such as particular
places or emotions) that led to high or low risk behaviour were identified and
an increasingly personal risk reduction plan was developed. (A detailed
protocol for the five sessions is freely available on the journal’s website).
Adherence counselling was also separately provided on three
Almost all participants were men, and PEP had commonly been
prescribed after unprotected anal sex (80.1%), unprotected vaginal sex (7.5%)
or oral sex to ejaculation (5.9%) in the previous 72 hours. Four out of ten
people receiving PEP knew that their partner was HIV-positive.
To assess the impact of the two styles of counselling, the
behaviour of participants was assessed at the time of taking PEP and one year
When the data for all participants were analysed together,
the extra intervention appeared to provide a modest benefit, but perhaps one
that could not justify the cost of its provision.
The study’s primary outcome was change in the number of
unprotected anal or vaginal sex acts. In the six months before taking PEP,
participants had had unprotected sex an average of 5.5 times. In people who
received two counselling sessions, this dropped by a mean of 1.8, while those
getting the extra sessions had 2.3 fewer unprotected sex acts.
The results are more interesting if we only look at those
individuals who were taking more sexual risks to begin with. A fifth of the
participants had had unprotected sex four or more times in the six months
before taking PEP, and the extra counselling had much more impact in this
In terms of the primary outcome, those with higher risk receiving
the standard two sessions had a reduction in 7.0 unprotected sexual acts,
whereas in those getting the extra sessions the average reduction was 13.2 acts.
Whereas 31.5% of higher-risk individuals receiving the
standard intervention felt the need to come back for a second course of PEP
within a year, this was case in 17.1% of those receiving five sessions.
And most importantly, fewer people were HIV-positive one
year later. Among those with higher risk who received two sessions, 12.3%
seroconverted. In those who received five sessions, 2.4% did so. (These
infections are likely to be due to risk behaviour in the months after taking
PEP, not the failure of PEP to prevent infection).
The researchers say that while, overall, two session
counselling is non-inferior, this is not the case for those who have taken
greater sexual risks. “For riskier individuals the three additional sessions
may be necessary for risk behaviours to decrease,” they say.
Clinicians providing PEP need to take a sexual history in
order to target additional counselling at those who would benefit from it.
While PEP can provide
a benefit to individuals, the authors say that PEP will only make a public
health impact “if it is targeted, used as a tool to leverage additional
interventions, and the lessons learned from this study are adopted.”