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Condoms reduce the risk of HIV infection by 80%(1). There is a
mounting body of evidence however, to show that they also lead to an
increase in promiscuity and encourage individuals to engage in more high
risk behaviour more frequently and to have relations with high risk
individuals(2). There comes a point were the protective effect of the
condom is offset by the behavioural change that it elicits. This is the
phenomenon of “risk compensation”. Some Individuals mistakenly believe
themselves to be invulnerable and thus engage in high risk behaviour
thereby negativing the protective effect of the condom. This is amenable
to a simple mathematical model.
The risk of HIV infection in a given community following sex with a given
individual is x. Condom use reduces this risk to 0.2x. The risk of
contracting HIV following sex with n partners, using a condom which each
partner, is given by
1 – (1- 0.2x)^n
The risk of acquiring HIV following relations with m partners with no
condom use is.
1- (1-x)^m
When the two risks are equivalent:
1 – (1- 0.2x)^n = 1- (1-x)^m
(1- 0.2x)n = (1-x)m
nlog(1-0.2x) = mlog(1-x)
n/m = log (1-x)/log(1-0.2x)
The ratio n/m refers to how many times more partners an individual
must have before the protective effect of the condom is abrogated by the
promiscuity it elicits. Solving this equation for the epidemiological
prevalence of HIV, this value is five. Hence if the presence of condoms
leads to a five fold increase in the number of sexual occasions then the
net risk reduction effect of the condom is extinguished. This simple
analysis neglects to consider the fact that there is zero risk in the case
of abstinence. It also fails to take into account the potential for
increased engagement in high risk behaviour with high risk individuals.
These factors would serve to reduce this ratio.
The “condom only message” simply is not working. Current evidence shows
that HIV rates, even in the Western World, are on the rise(3). As doctors
we should not be shy to promote other effective ways of arresting the HIV
pandemic which include abstinence and fidelity or ridicule those who
attempt to promulgate such a message. These methods are effective and cost
nothing, however unpalatable they may be (4). They do not have the same
economic or environmental ramifications of the condom nor do they require
the same industrial and educational infrastructure for their dissemination
and effective use. These are important considerations in the Third World.
Durex reported pre-tax profits up by 46 % to £32.5 million for a six month
period in 2008(5). There is clearly money to be made from the world-wide
distribution of condoms.
1. Kamerow D. The papal position on condoms and HIV. BMJ. 2009 Mar
25;338:b1217
2. Cassell MM, Halperin DT, Shelton JD, Stanton D. Risk compensation:
the Achilles' heel of innovations in HIV prevention? BMJ. 2006; 332:605-
607
3. Janice Hopkins Tanne HIV prevalence in US capital is at epidemic
level BMJ 2009;338:b1205
4. Shelton JD, Halperin DT, Nantulya V, Potts M, Gayle HD, Holmes KK.
Partner reduction is crucial for balanced "ABC" approach to HIV
prevention. BMJ. 2004; 328:891-893
Prof Ed Green, a Harvard AIDS expert (1) and a Guardian commentary
(2) have both supported the Pope's recent statement on condoms and both
give rational explanations as to why they do so, with no reference to
religious dogma.
Green is a self-confessed secularist but since the Guardian writer is
a Catholic, I won't hold my breath about you mentioning either article in
the coming week's news bulletin. Clearly you have made your mind up
already at the BMJ and any balance in reporting on this issue is not to be
expected. At least those interested enough to go online here may be able
to see there are actually two sides to this argument.
The Catholic Church Has A Valid Argument
Condoms reduce the risk of HIV infection by 80%(1). There is a
mounting body of evidence however, to show that they also lead to an
increase in promiscuity and encourage individuals to engage in more high
risk behaviour more frequently and to have relations with high risk
individuals(2). There comes a point were the protective effect of the
condom is offset by the behavioural change that it elicits. This is the
phenomenon of “risk compensation”. Some Individuals mistakenly believe
themselves to be invulnerable and thus engage in high risk behaviour
thereby negativing the protective effect of the condom. This is amenable
to a simple mathematical model.
The risk of HIV infection in a given community following sex with a given
individual is x. Condom use reduces this risk to 0.2x. The risk of
contracting HIV following sex with n partners, using a condom which each
partner, is given by
1 – (1- 0.2x)^n
The risk of acquiring HIV following relations with m partners with no
condom use is.
1- (1-x)^m
When the two risks are equivalent:
1 – (1- 0.2x)^n = 1- (1-x)^m
(1- 0.2x)n = (1-x)m
nlog(1-0.2x) = mlog(1-x)
n/m = log (1-x)/log(1-0.2x)
The ratio n/m refers to how many times more partners an individual
must have before the protective effect of the condom is abrogated by the
promiscuity it elicits. Solving this equation for the epidemiological
prevalence of HIV, this value is five. Hence if the presence of condoms
leads to a five fold increase in the number of sexual occasions then the
net risk reduction effect of the condom is extinguished. This simple
analysis neglects to consider the fact that there is zero risk in the case
of abstinence. It also fails to take into account the potential for
increased engagement in high risk behaviour with high risk individuals.
These factors would serve to reduce this ratio.
The “condom only message” simply is not working. Current evidence shows
that HIV rates, even in the Western World, are on the rise(3). As doctors
we should not be shy to promote other effective ways of arresting the HIV
pandemic which include abstinence and fidelity or ridicule those who
attempt to promulgate such a message. These methods are effective and cost
nothing, however unpalatable they may be (4). They do not have the same
economic or environmental ramifications of the condom nor do they require
the same industrial and educational infrastructure for their dissemination
and effective use. These are important considerations in the Third World.
Durex reported pre-tax profits up by 46 % to £32.5 million for a six month
period in 2008(5). There is clearly money to be made from the world-wide
distribution of condoms.
1. Kamerow D. The papal position on condoms and HIV. BMJ. 2009 Mar
25;338:b1217
2. Cassell MM, Halperin DT, Shelton JD, Stanton D. Risk compensation:
the Achilles' heel of innovations in HIV prevention? BMJ. 2006; 332:605-
607
3. Janice Hopkins Tanne HIV prevalence in US capital is at epidemic
level BMJ 2009;338:b1205
4. Shelton JD, Halperin DT, Nantulya V, Potts M, Gayle HD, Holmes KK.
Partner reduction is crucial for balanced "ABC" approach to HIV
prevention. BMJ. 2004; 328:891-893
5.http://business.timesonline.co.uk/tol/business/industry_sectors/health/a...
Competing interests:
None declared
Competing interests: No competing interests