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| GMCarter 2004-10-26, 7:06 pm |
| From the Cochrane Collaboration with regard to the use of condoms in
the prevention of heterosexually transmitted HIV disease.
George M. Carter
**
http://cochrane.bireme.br/cochrane/...lang=es&dblang=
Condom effectiveness in reducing heterosexual HIV transmission
Weller S, Davis, K.
--------------------------------------------------------------------------------
This review should be cited as: Weller S, Davis, K.. Condom
effectiveness in reducing heterosexual HIV transmission (Cochrane
Review). In: The Cochrane Library, Issue 2, 2004. Oxford: Update
Software.
A substantive amendment to this systematic review was last made on 19
November 2001. Cochrane reviews are regularly checked and updated if
necessary.
Abstract
Background: The amount of protection that condoms provide for HIV and
other sexually transmitted infections is unknown. Cohort studies of
sexually active HIV serodiscordant couples with follow-up of the
seronegative partner, provide a situation in which a seronegative
partner has known exposure to the disease and disease incidence can be
estimated. When some individuals use condoms and some do not, namely
some individuals use condoms 100% of the time and some never use (0%)
condoms, condom effectiveness can be estimated by comparing the two
incidence rates. Condom effectiveness is the proportionate reduction
in disease due to the use of condoms.
Objective: The objective of this review is to estimate condom
effectiveness in reducing heterosexual transmission of HIV.
Search strategy: Studies were located using electronic databases
(AIDSLINE, CINAHL, Embase, and MEDLINE) and handsearched reference
lists.
Selection criteria: For inclusion, studies had to have: (1) data
concerning sexually active HIV serodiscordant heterosexual couples,
(2) a longitudinal study design, (3) HIV status determined by
serology, and (4) contain condom usage information on a cohort of
always (100%) or never (0%) condom users.
Data collection and analysis: Studies identified through the above
search strategy that met the inclusion criteria were reviewed for
inclusion in the analysis. Sample sizes, number of seroconversions,
and the person-years of disease-free exposure time were recorded for
each cohort. If available, the direction of transmission in the cohort
(male-to-female, female-to-male), date of study enrollment, source of
infection in the index case, and the presence of other STDs was
recorded. Duplicate reports on the same cohort and studies with
incomplete or nonsepecific information were excluded. HIV incidence
was estimated from the cohorts of "always" users and for the cohorts
of "never" users. Effectiveness was estimated from these two incidence
estimates.
Main results: Of the 4709 references that were initially identified,
14 were included in the final analysis. There were 13 cohorts of
"always" users that yielded an homogeneous HIV incidence estimate of
1.14 [95% C.I.: .56, 2.04] per 100 person-years. There were 10 cohorts
of "never" users that appeared to be heterogeneous. The studies with
the longest follow-up time, consisting mainly of studies of partners
of hemophiliac and transfusion patients, yielded an HIV incidence
estimate of 5.75 [95% C.I.: 3.16, 9.66] per 100 person-years. Overall
effectiveness, the proportionate reduction in HIV seroconversion with
condom use, is approximately 80%.
Reviewers' conclusions: This review indicates that consistent use of
condoms results in 80% reduction in HIV incidence. Consistent use is
defined as using a condom for all acts of penetrative vaginal
intercourse. Because the studies used in this review did not report on
the "correctness" of use, namely whether condoms were used correctly
and perfectly for each and every act of intercourse, effectiveness and
not efficacy is estimated. Also, this estimate refers in general to
the male condom and not specifically to the latex condom, since
studies also tended not to specify the type of condom that was used.
Thus, condom effectiveness is similar to, although lower than, that
for contraception.
see website for full report
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| PaulKing 2004-10-26, 7:06 pm |
| Eighty per cent (which is not the conclusion of any study below) would
still mean one failure in five sex acts. So in reality with 100% correct
use you could never have sex with any for more than one week without a
100% chance of failure. SOME PROTECTION....IF HIV EXISTED.
_________
THE MAS OF STUDIES FIND NO EVIDENCE OF PROTECTION
FAILURES OF THE MEMBRANE OF THE CONDOM
1) Permeability of the latex membrane for microparticles, STD agents and
HIV
In 1977 D.Barlow v advanced the hypothesis of the existence of some pores
in
the latex membrane of a condom in order to explain why this did not
appear
to protect
against non-gonococcal urethrites and genital infections with Condylomata
acuminata.
This hypothesis has been revived in order to account for HIV infections
acquired during
sexual intercourse "protected" by use of a condomvi.
S.G.Arnold et al. (1988) vii have examined latex gloves from four
manufacturers using scanning electron microscopy and X-ray analysis.
They found that all of the gloves had pits 3-15µm wide and up to 30µm
deep
on both interior and exterior
surfaces.
Irregular particles (30-50µm) containing silicon and magnesium were
embedded in the latex deeply enough to cause pits themselves.
__________
REF: -
Freeze-fractured
1 Pontifical Council for the Family, Rome. Current adress: 18 via della
Traspontina, Roma, 00193, Italy.
2 English translation by D.E.Parry from the revised original article « Le
"sexe sűr" et le préservatif face au défi du Sida», Medicina e Morale,
n°4, 1997, pp.689-726.
2 sections of all gloves showed cavities throughout the matrix and
tortuous channels
(5µm) penetrating the entire thickness of the glove.
__________
Such irregularities in latex membrane surface and structure do not seem
to
be encountered in condoms, at least when they are new, and have not been
exposed to heat, oxygen, or ozone.
However, under scanning electron microscopy, the surface of a latex
condom
membrane is not uniformly smooth: it appears made of smooth areas
separated by puckers and dimples scattered across the specimen (viii).
There are hollows and irregular projections on this surface, with
irregular, dense inclusions (ix).
Although numerous pores are visible in scanning electron microscopy of
natural condoms (x,) no
evidence of breaks, fissures or pores have yet been reported in the few
published
transmission electron microscope studies of latex condoms (xi).
Some authorities have concluded that latex membranes of condoms, despite
their nonhomogeneous structure and the irregularity of their surface,
could be considered free of microscopic pores, of a size down to that of
the smaller virus.
However, these results have been put in question.
First, as Rosenzweig et al.(xviii) say it, all the aboved mentioned
electron microscopic studies of condoms have been "predominantly
anecdotal".
These later authors, in their own study of thirty samples from fifteen
non-lubricated Trojan condoms, did find that a large proportion of these
samples have visible surface abnormalities, with only 30% of all condoms
tested completely free of detectable defects under all magnifications.
50%
of the samples revealed a surface abnormality interpreted as either
cracking, melting or both.
Second, in vitro studies about the grade of impermeability of condoms
membranes to microorganisms, using a condom plunged into a culture
medium,
are few, and limited to small sample sizes.
Confidence intervals constructed around reported failure rates indicate
that "true" permeability rates could be quite high, and new data suggest
that some condom do leak HIV and that leakage is not necessarily
related to whether or not they are made of late (xxix).
Moreover, experience with STDs shows the need for prudence in
extrapolating results obtained in vitro to situations in (vivoxx).
Third, optimism about condoms membrane integrity has been shaken after
closely controlled condoms, coming from known manufacturers, had shown a
permeability to microspheres of greater size than that of HIV (6 condoms
out of 69)xxi.
Carey et al.(xxii) observed the passage of polystyrene microspheres, 110
nm diameter ( HIV diameter is from 90nm to 130 nm) across 33% of the
membranes of the latex condoms which they studied (29 over 89
nonlubricated latex condoms). More recently,
Lytle et al., while criticizing the "exaggerated conditions" of the in
vitro, polystyrene microspheres test carried out by Carey et al., found
that 2,6% (12 of 470) of the latex
condoms did allow some virus penetration, with no difference between
lubricated and nonlubricated condoms (xxiii).
It has been said that since HIV in semen is associated with white blood
cells (and, may be, also with spermatozoa) and since neither spermatozoa
nor white cells can pass through these very small hypothetic "pores" in
the latex, then HIV itself cannot pass. So these "pores", even if they do
exist, could not therefore be of such importance. But this is deceptive.
In fact HIV is present in sperm in two forms: associated with white blood
cells and as free virus particles (xxiv); And C.J.Miller et al.
have demonstrated that cell-free virus preparations are capable of
producing HIV infection by the genital routexxv.
Given their size, such free viruses from semen could transit through the
smallest defect of the membrane of a condom and reach, in the organism of
the sexual partnerxxvi, CD4 in Langerhans, lymphocytes and macrophages
cells. They may also potentiate indirectly the infectivity of HIV-1 in
semen, regardless of
HIV-1 source (xxvii).
A - THE PERFORMANCE OF THE CONDOM AS A CONTRACEPTIVE
The Pearl contraceptive index is in fact relatively high for the condom,
being between 8 and 15 (with extremes reaching up to 28)li lii.
The failure rate of the condom in preventing pregnancy, defined as the
probability of pregnancy over one year for a woman for whom the condom is
the only means of contraception is of the order of 15%liii liv.
If the admitted failure rate of condom used as a method of contraception
is said to be 3% for couples using condoms "perfectly" (both
consistently
and correctly)lv,
this failure rate is found to be 4% with couples highly motivated lvi and
rise to 12% in "typical couples experience"(Albert and Hatcher,
1991)lvii.
Moreover, these contraceptive failure rates are conservative estimates,
since each exposure does not result in pregnancy lviii.
This condom failure may explain the relationship between condom use and
teen age pregnancy ratelix. 11% of the women's unplanned pregnancies at
the Grady Memorial Hospital in Atlanta, USA, were attributed to condom
failurelx. 27% of the abortions performed at the hôpital Saint Louis in
Paris are said to be requested because of condom failure lxi.
Of the 4,666 women who came to be aborted at the Marie Stopes Centre in
Leeds, England, between 1989 and 1993, 40% of them blamed condom failure
for their pregnancyl xii.
In the study reported by M.Gabbay et al.(1996)lxiii,
83% of female students presenting for post-coital contraception at the
Rusholme Health Centre, Manchester, claimed condom failure as the cause.
One of the factors for contraceptive failure when using a condom is
certainly the inexperience of the users lxiv. A large scale American
study
on the efficiency of different
condoms to prevent pregnancies showed a failure rate of 15% among young
users in their first year of use, a rate which reduces to 2% among
couples
who are expert in the use of this device lxv.
If we now consider the efficiency of the condom when used as a
prophylactic against STDs, we find a significant failure rate which
appears roughly inversely
proportional to the size of the pathogenic agentlxvi.
N.J.Fiumaralxvii reckons that the condom, which is in theory useful
against STDs, is, in practice, inefficient. J.Pemberton et al.
(1972)lxviii, while examining 2,093 STD cases diagnosed in Belfast found
a
lower percentage of syphilis and gonorrhea among
condom users, but a higher proportion of non-gonococcal urethrites and
idiopathic
STDs.
W.M.McCormack et al.lxix, studying a group of 140 students who were
carriers of urethral T-Mycoplasmas following sexual relations, found
14.3%
colonization among those students who always used a condom.
D.Barlow (1977)lxx, for a total of 3,543 diagnoses of gonorrhea in a
six-month period among 3300 patients, found that condom users (247) only
had slightly fewer
STD cases (259) compared to non-users.
Non-specific urethrites (mainly due to Chlamydia trachomatis and
Ureaplasma urealyticum, 200nm in diameter), were found in this series
with
the same frequency for both users and non-users of condoms.
Infections with Condylomata acuminata (genital warts) were more frequent
(5%) among condom users than among non-users (4.6%).
Cohen et al. (1992)lxxi, made a study in which those patients who had
contracted an STD received instruction in condom usage. In the nine
months
after this instruction, 19.9% of the males and 12.6% of the females
returned with a fresh STD, some
returning several times. In fact, STD reinfection rate increased even
among females after this instruction.
A study made in a genitourinary clinic in London (Evans et al. 1995)lxxii
showed that an increase in the use of condoms from 1982 to 1992 from 4%
to
21% did not have an effect on the number of viral STDs observed during
this same period.
The same authors found that increasing condom use with regular partners
correlated with decreasing incidence of gonorrhea, chlamydial infections,
and trichomoniasis in women having regular partners, but did not show
that
trend with non-regular partners.
Moreover, condom use was ineffective in the prevention of non-gonococcal
urethritis, candidosis, genital herpes and genital wartslxxiii.
J.M.Zenilman et al. (1995) lxxiv, studying the self-reported use of
condoms, and the occuring sexually transmitted diseases in a cohort from
a
high-risk population, comprising 323 males and 275 female, found,
surprisingly, that 15% of the men who
were "always" condom users had incident STDs, compared with 15.3% of the
"never users"; 25.5% of the women who were "always" users had incident
STDs, compared with 26.8% of "never" users.
This obvious lack of correspondence between the selfreported "always"
condom use and an effective prevention of STDs left these authors rather
perplexed, and they questioned the quality of self-reporting.
However, a recent study of M.Shew et al.(1997)lxxv on condom use among
adolescents found that selfreported condom use was valid, at least in
this
sample, although consistent condom use did not eliminate STDs (one STD
for
20 respondents for one in five when no condom was used).
K.M.Stone et al.(1986)lxxvi, in a review of statistical differences on
prevention of STDs, recommended condom use in "at risk" sexual relations,
while at the same time indicating the limits of the protection thus
obtained: one simply finds "less risk" of acquiring an urethral gonorrhea
gonococcal urethrite, a urethrite from Ureaplasma urealyticum, or other
venereal diseases among condom users than among non-users.
The condom, in the cases examined by K.M.Stone, seems particularly
effective against gonococcal urethrites, while not protecting against
non-gonococcal urethrites.
J.Sanchez et al.lxxvii, in a one-year survey of the prevalence and
determinats of
STDs among 435 female sex workers attending the Centro antivenereo of
Lima
(Perú), found that consistent condom use during the past year was
associated with somewhat decreased risk of gonorrhea and with VDRL
titer>=1:4, but not with a decrease in chlamydial infection.
This study did not show statistically significant relationship of
longterm
consistent condom use with antibody to either Herpes simplex virus type 2
or H.ducreyi infection.
| |
| Moira de Swardt 2004-10-26, 7:06 pm |
|
"PaulKing" <aimulti@aimultimedia.com> wrote in message
> Eighty per cent (which is not the conclusion of any study below)
would
> still mean one failure in five sex acts. So in reality with 100%
correct
> use you could never have sex with any for more than one week
without a
> 100% chance of failure. SOME PROTECTION....IF HIV EXISTED.
80% is a cumulative figure.
But you're not good at stats, maths or honest reporting, are you?
Moira, the Faerie Godmother
| |
| PaulKing 2004-10-26, 7:06 pm |
| That figure is based on them 'being used correctly".
The CDC admits that 32% of failures are from improper use.
Add 20% and 32% and you get...........
OVER HALF FAIL
| |
| GMCarter 2004-10-27, 10:06 pm |
| On Thu, 21 Oct 2004 16:16:00 -0400, "PaulKing"
<aimulti@aimultimedia.com> wrote:
>"Suggesting people NOT bother with condoms is idiotic."
>
>Suggesting people use something that will give them cancer and cause their
>children to be born with birth defects is criminal.
Yeah, it would be. Good thing condoms don't do that. Actually, they
help PREVENT unwanted pregnancies.
George M. Carter
| |
| PaulKing 2004-10-27, 10:06 pm |
| "Suggesting people NOT bother with condoms is idiotic."
Suggesting people use something that will give them cancer and cause their
children to be born with birth defects is criminal.
| |
| Moira de Swardt 2004-10-29, 7:06 pm |
|
"PaulKing" <aimulti@aimultimedia.com> wrote in message
> That figure is based on them 'being used correctly".
> The CDC admits that 32% of failures are from improper use.
> Add 20% and 32% and you get...........
> OVER HALF FAIL
You really don't understand stats, do you?
32% is 32% of those 20%
Moira, the Faerie Godmother
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