Medical Forum / Diseases and Disorders / AIDS / October 2004
Condoms
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GMCarter - 20 Oct 2004 17:22 GMT 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/show.php?db=&mfn=&id=_ID_CD003255&lang=es&dblang= Condom effectiveness in reducing heterosexual HIV transmission
Weller S, Davis, K.
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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
PaulKing - 21 Oct 2004 04:41 GMT 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 sûr" 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.
GMCarter - 21 Oct 2004 10:42 GMT >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. It does. No one ever said condoms were 100% successful. However, they reduce the risk of HIV infection substantially. Suggesting people NOT bother with condoms is idiotic.
George M. Carter
PaulKing - 21 Oct 2004 21:16 GMT "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.
GMCarter - 21 Oct 2004 22:13 GMT >"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
Moira de Swardt - 21 Oct 2004 10:59 GMT "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 - 21 Oct 2004 21:18 GMT 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
Moira de Swardt - 23 Oct 2004 18:30 GMT "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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