Friday, 10th of April 2009 |
CSU 20/2009: 1) READER COMMENT / 2) MODELING THE IMPACT OF MALE CIRCUMCISION/ CALMETTE AND GUERIN
1) READER COMMENT
Reader Bob Bailey, of the University of Illinois, comments as follows on
the social science side of male circumcision:
‘The below is the reference to a review of acceptability studies in
nine different countries in sSA. Also, for answers to many questions about circumcision,
you might want to turn to the website recently created by WHO/UNAIDS
entitled, The Male Circumcision Clearinghouse. The website is
at http://www.malecircumcision.org/publicationsmale_circumcision_publications.html
Westercamp N, Bailey RC. Acceptability of male circumcision for prevention
of HIV/AIDS in sub-Saharan Africa: a review. AIDS Behav 2007;11(3):341-355.
2) MODELING THE IMPACT OF MALE CIRCUMCISION
Writing in the International Journal of Epidemiology, Gray and colleagues
review the evidence on male circumcision and HIV prevention, especially in
the light of different models of roll-out options for MC. Their conclusions,
quoted in the excerpts below, and those of Londish and Murray, are likely
to generate much discussion.
Where 5 to 15 circumcisions prevent a single HIV infection, then MC is
extremely cost-effective. Few interventions prevent HIV for a unit cost of <
$1000 per new infection, a figure likely to be achieved in high prevalence
countries where circumcision costs less than $50 per procedure. More
contentious is a low priority to infant circumcision, which takes little
account of the fact that circumcision of neonates is relatively simpler and
less expensive, and that HIV/AIDS in Africa is likely to remain a pandemic
in future decades, when today’s infants become sexually active. Among older
age groups, some writers on the subject would prioritize boys in their teens
rather than the 20-34 year age group.
There is no 'either-or' here; the same resources can serve to
circumcise younger boys, adolescent males and adults.
From the editorial:
‘In most sub-Saharan African settings, the number of surgeries per HIV
infection averted over a decade ranges from 5–15, depending on male HIV
incidence. This makes circumcision a highly cost effective intervention,
particularly when costs are discounted by savings for future antiretroviral
care due to prevention of HIV acquisition.’
‘. . . as suggested by Londish and Murray, priority might be given to men
aged 20–34 among whom incidence is generally greatest in Africa, and
because such men often have relationships with younger female partners, the derivative
benefits to women are likely to be maximized. . .’
‘ Models can also address the question of whether to devote resources to
surgery in adolescents and adults, or to infant circumcision. Again, the
results are clear. Adolescent and adult surgery will reduce HIV over 10–20
years, whereas with infant circumcision, HIV impact will be delayed for more
than 20 years due to delayed onset of sexual activity.’
Both the editorial, and the article by Londish and Murray from the same
journal, are available online, with weblinks. The article is at
http://ije.oxfordjournals.org/cgi/content/abstract/37/6/1246 and the
editorial is at http://ije.oxfordjournals.org/cgi/content/full/37/6/1253 .
Good reading.
BD
International Journal of Epidemiology, Volume 37, Number 6, Pp. 1253-1254
Published by Oxford University Press on behalf of the International
Epidemiological Association © The Author 2008; all rights reserved.
Commentary: Disease modelling to inform policy on male circumcision for HIV
prevention
Ronald H Gray1,, Maria J Wawer 1, Godfrey Kigozi 2 and David Serwadda 3
1 Johns Hopkins University, Bloomberg School of Public Health, Baltimore,
Maryland, USA.
2 Rakai Health Sciences Program, Entebbe, Uganda.
3 School of Public Health, Makerere University, Kampala, Uganda.
Corresponding author. E-mail: rgray@jhsph.edu
Accepted 7 April 2008
The findings from three randomized trials 1–3 and multiple observational
studies4 that male circumcision prevents HIV acquisition in men has been
welcomed as an historic opportunity to control the HIV epidemic,
particularly in sub-Saharan Africa.5 However, the challenges are daunting
because we have never attempted to use surgery as a means of controlling an
infectious disease, the African health infrastructure is weak and trained
personnel required to provide circumcision surgery on a massive scale are
limited. Therefore, modelling the impact of circumcision on the future
course of the HIV epidemic is needed to persuade health authorities and
donors to invest resources in this unprecedented initiative.
The paper by Londish and Murray in this volume 6 adds to the growing body of
models, all of which suggest that circumcision has the potential to abate
but not abolish the African HIV epidemic over a period of 10-20 years.7–10 A
variety of model projections were reviewed at a recent Joint United Nations
Programme on AIDS (UNAIDS) meeting at Imperial College, London (March 5–6,
2008). A report will be forthcoming. The models have varied in their
assumptions and structures, and in the endpoints used (e.g. HIV prevalence
or incidence over time, HIV infections or AIDS deaths prevented, the number
of surgeries needed to avert one HIV infection and the costs per infection
averted). Irrespective of these differences in modelling methods and
outputs, the direct biological effect of circumcision on reducing HIV
acquisition in men by 60%, and the secondary protection afforded to women
via reduced exposures to HIV infected men, are so overwhelming that, under
most plausible scenarios, the impact of circumcision on the African HIV
epidemic is clear and substantial. The impact of circumcision will likely be
greatest in settings, such as those in southern Africa, where HIV incidence
is high and the prevalence of circumcision is low.
The circumcision trials provide an estimate on the numbers needed to treat
per HIV infection over a short period of two years. However, since the
efficacy of circumcision is likely to be life long, models can estimate the
number of surgeries needed to prevent one HIV infection over a period of
10–20 years. In most sub-Saharan African settings, the number of surgeries
per HIV infection averted over a decade ranges from 5–15, depending on male
HIV incidence. This makes circumcision a highly cost effective intervention,
particularly when costs are discounted by savings for future antiretroviral
care due to prevention of HIV acquisition.
Other policy relevant questions addressed by modelling include whether to
provide services to all men or to focus on specific segments of the
population such as limited age groups or subgroups with higher sexual risk
behaviours. Thus, as suggested by Londish and Murray, priority might be
given to men aged 20–34 among whom incidence is generally greatest in
Africa, and because such men often have relationships with younger female
partners, the derivative benefits to women are likely to be maximized.
Similarly, a focus on high risk core groups such as STD clinic attendees or
clients of commercial sex workers might provide greater benefit. However,
there are practical limitations to such strategies. First, HIV prevalence
will be high in such high incidence subgroups, and since circumcision of
HIV-infected men does not appear to directly benefit women,11 the impact of
the program will be diluted and there would be substantial number of
surgeries in already HIV infected men who may infect their female partners
if intercourse is resumed before full wound healing is complete.11 Second,
such ‘targeting’ could exclude large segments of the male population who,
given the belief that circumcision is protective, might seek services from
unsafe sources. Therefore, although models predict greater impact from
targeting specific adult age or risk groups, this may be of limited
practical programmatic value.
Models can also address the question of whether to devote resources to
surgery in adolescents and adults, or to infant circumcision. Again, the
results are clear. Adolescent and adult surgery will reduce HIV over 10–20
years, whereas with infant circumcision, HIV impact will be delayed for more
than 20 years due to delayed onset of sexual activity. Similarly, models can
provide guidance for the speed of program scale up. Rapid achievement of
high circumcision coverage will maximize impact by more rapidly preventing
new HIV infections in the population.
In summary, modelling the effectiveness of circumcision for HIV prevention
can be an important tool for policy and planning. The only remaining
question is whether policy makers will use this information in their
decision making, whether they will devote resources to this initiative, and
whether programs can be brought to scale in a timely manner.
References
1 Gray RH, Kigozi G, Serwadda D, et al. Male circumcision for HIV prevention
in men in Rakai, Uganda: a randomized trial. Lancet (2007) 24:657–66.
2 Bailey RC, Moses S, Parker CB, et al. Male circumcision for HIV prevention
in young men in Kisumu, Kenya: a randomized controlled trial. Lancet (2007)
369:643–56.[CrossRef][ISI][Medline]
3 Auvert B, Taljaard D, Lagarde E, Sobngwi-Tambekou J, Sitta R, Puren A.
Randomized, controlled intervention trial of male circumcision for reduction
of HIV infection risk: the ANRS 1265 Trial. PLoS Med (2005) 11:e298. Epub
2005 October 25. Erratum in: PLoS Med 2006 May;3:e298.
4 Weiss HA, Quigley MA, Hayes RJ. Male circumcision and risk of HIV
infection in sub-Saharan Africa: a systematic review and meta-analysis. AIDS
(2000) 14:2361–70.[CrossRef][ISI][Medline]
5 WHO and UNAIDS press release on recommendations for male circumcision on
prevention of HIV infection (March 28 2007). Available at:
http://www.who.int/mediacentre/news/releases/2007/pr10/en/print.html.
6 Londish GC, Murray JM. Significant reduction in HIV prevalence according
to male circumcision intervention in sub-Saharan Africa. Int J Epidemiol.
(2008) 37:1246–1253.[Abstract/Free Full Text]
7 Nagelkerke NJ, Moses S, de Vlas SJ, Bailey RC. Modelling the public health
impact of male circumcision for HIV prevention in high prevalence areas in
Africa. BMC Infect Dis (2007) 7:16.[CrossRef][Medline]
8 Gray RH, Li X, Kigozi G, et al. The impact of male circumcision on HIV
incidence and cost per infection prevented: a stochastic simulation model
from Rakai, Uganda. AIDS (2007) 21:845–50.[ISI][Medline]
9 Kahn JG, Marseille E, Auvert B. Cost-effectiveness of male circumcision
for HIV prevention in a South African setting. PLoS Med (2006)
3:e517.[CrossRef][Medline]
10 Williams BG, Lloyd-Smith JO, Gouws E, et al. The potential impact of male
circumcision on HIV in Sub-Saharan Africa. PLoS Med (2006)
3:e262.[CrossRef][Medline]
11 Wawer M, Kigozi G, Serwadda D, et al. Trial of male circumcision in HIV+
men, Rakai, Uganda: Effects in HIV+ men and in women partners. Proceedings
of the 15th Conference on Retroviruses and Opportunistic Infections. Boston,
February 3–6, 2008. Abstract 33LB CROI, Alexandria, VA.
3) CALMETTE AND GUERIN
Most readers of these updates are familiar with BCG, but some may not know
about the two French researchers who gave their names to the Bacille
Calmette-Guerin, a modified form of Mycobacterium bovis used in most
countries against tuberculosis (some studies show a protective effect of BCG
against leprosy as well).
See their story at http://www.technet21.org/Articles/BCG_vaccine.html
Cross-posted, with thanks, from EPI Technet.
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