Condom effectiveness in
reducing heterosexual HIV
transmission (Review)
Weller
S, Davis, K
This
is a reprint of a Cochrane review, prepared and maintained by The Cochrane
Collaboration and published in The Cochrane Library 2005, Issue 3
http://www.thecochranelibrary.com
T A B L E O F C
O N T E N T S
ABSTRACT
SYNOPSIS
BACKGROUND
OBJECTIVES
CRITERIA
FOR CONSIDERING STUDIES FOR THIS REVIEW
SEARCH
STRATEGY FOR IDENTIFICATION OF STUDIES
METHODS
OF THE REVIEW
DESCRIPTION
OF STUDIES
METHODOLOGICAL
QUALITY
RESULTS
DISCUSSION
AUTHORS'
CONCLUSIONS
ACKNOWLEDGEMENTS
POTENTIAL
CONFLICT OF INTEREST
SOURCES
OF SUPPORT
REFERENCES
TABLES
Characteristics
of included studies
Characteristics
of excluded studies
ADDITIONAL
TABLES
Table 01. Incidence rate information by study
INDEX
TERMS
COVER
SHEET
COMMENTS
AND CRITICISMS
Condom effectiveness in reducing
heterosexual HIV transmission (Review) I Copyright ©2005 The Cochrane
Collaboration. Published by John Wiley & Sons, Ltd
Condom effectiveness in
reducing heterosexual HIV
transmission (Review)
Weller
S, Davis, K
Status:
Commented
This record should be cited as:
Weller S, Davis, K. Condom effectiveness
in reducing heterosexual HIV transmission. The Cochrane Database of Systematic
Reviews 2002,
Issue 1. Art. No.: CD003255. DOI: 10.1002/14651858.CD003255.
This version _rst published online: 21 January
Date of most recent substantive amendment: 19 November 2001
A B S T R A C T
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.
Objectives
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
identi_ed 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 nonsepeci_c
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
_nal 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%.
Authors' 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.
S Y N O P S I S
Using
condoms consistently reduces sexual transmission of HIV infection Sexual
intercourse and contact with contaminated blood products (e.g., intravenous
drug use) account for the majority of HIV infections. The wearing of condoms
during sexual intercourse has been promoted to reduce the infection and spread
of sexually transmitted infections (STIs) such as HIV. The review of studies
found that condoms, when used consistently, substantially reduced HIV infection
but did not totally eliminate the risk of infection.
B A C K G R O U N D
Heterosexual
intercourse is the primary mode of HIV infection worldwide. In the
However,
the amount of protection condoms provide against HIV and other sexually
transmitted infections (STIs) is unknown. Design complexities and ethical
considerations make it dif_cult to study condom effectiveness for STIs. In
order to estimate efficacy, infection-free people must be sexually exposed to
infection, while some use a condom and some do not. Ideally, individuals should
be assigned to use or not use a condom at random (randomized controlled trial).
Because it is unethical to expose someone to a possibly serious disease
(especially if the disease is uncurable) or to withhold treatment from someone
with a treatable disease, studies that might provide clear evidence about
ef_cacy are not possible.
Instead,
condom ef_cacy must be estimated from observational studies, where individuals
happen to be exposed to infection and happen to use or not use condoms. It is
in these naturally occuring, although unfortunate, \experiments" that we
are able to obtain information on condom effectiveness for prevention of STIs.
In fact, HIV offers an unique opportunity to study
condom effectiveness, since it can be sexually transmitted, has no cure, and infection
can be confirmed by serology.
Effectiveness
of condoms as a contraceptive provides insight into their usefulness as a
barrier device capable of preventing HIV transmission. Contraceptive
effectiveness is de_ned as the proportionate reduction in pregnancies caused by
use of a contraceptive method. It is estimated as one minus the ratio of the
pregnancy rate with a contraceptive method to the rate without any method for a
given time period (Trussel personal). The probabilities of contraception with (Vaughan
1981; Schirm 1982; Grady 1986; Glass 1974; Jones 1992; Hatcher 1998) and
without (Trussell 1987) condom usage can be transformed into rates (Trussel
personal) and provide an estimate of condom effectiveness for preventing
pregnancy of 90.7% to 98.6%.
Effectiveness
of condoms in reducing HIV transmission may be estimated in the same way as for
contraception. For HIV, the pro- portionate reduction in HIV due to condom
usage is calculated from the seroconversion rate (HIV incidence) among couples
always using condoms and the rate (HIV incidence) among couples never using
condoms. A comparison group of condom non-users
is essential to determine the reduction in
HIV incidence that is due to condom use. Since HIV serodiscordant couples
cannot ethically be assigned at random to condom user groups, estimates must be
obtained from observational studies. The best measure of condom effectiveness
is obtained from a comparison of serodiscordant, always- and never- condom
users having penetrative sexual intercourse. When one partner is HIV positive
and the other is not (serodiscordant) and they are sexually active, it ensures
that
the HIV negative partner is exposed to HIV.
In order to identify the source of exposure and to link the source of exposure
to transmission, the sexual relationship should be of some duration and
preferably be monogamous. The seronegative partner should not have any
nonsexual HIV risk factors, such as contact with contaminated blood products or
injection drug use (IDU).
The
lack of random assignment of individuals to use or not use condoms can result
in an unequal distribution of HIV risk factors across those categories and can
bias estimates of condom effectiveness. Factors associated with both
seroconversion and condom use can bias estimates of condom effectiveness.
Differences between \always" and \never" users in duration and
frequency of exposure or in infectivity and susceptibility can bias estimates.
Because
condom use is associated with HIV risk factors, the association between condom use
and seroconversion is biased by the self-selection of individuals into the
always and never condom usage groups. Notably, condom non-users in recent
studies may be more likely to be IDUs (Padian 1997) and may be more likely to
engage in other risky behaviors (Skurnick 1998; Kennedy 1993; Pinkerton 1995;
Ross 1988). Higher HIV transmission among partners of IDUs (Padian 1997) and a
preponderance of partners of IDU index cases among condom nonusers, can inate
incidence estimates for condom nonusers and result in an overestimation of
condom effectiveness.
Condom
failure can occur because of user failure and/or because of method/device
failure. User failure includes incorrect condom usage and other user factors
that result in high rates of breakage and slippage. Method failure is the
theoretical failure rate of the device, apart from user failure. Method failure
is assumed to be constant, although condoms may vary in quality and thus vary
in breakage, slippage, and leakage rates. Since method and user failure are
inextricably confounded, a study of condom efficacy would attempt to minimize
user failure to the extent possible: participants would receive instruction on
proper condom use and would be interviewed about if and how condoms were used.
Similarly, causes of method failure not related to the outcome (HIV) also would
be controlled: all particpants would receive high quality condoms of the same
material and the date and quality testing results would be reported by the
investigators. Without these guarantees, what is estimated in a study of
serodiscordant couples is condom effectiveness and not condom efficacy (e.g.,
how they perform under good, but not necessarily optimally controlled
conditions of use).
Various
estimates of condom effectiveness for reducing heterosexual transmission of HIV
are available from studies of serodiscordant couples. This review provides a
quantitative summary of those studies. An initial meta-analysis (Weller 1993)
estimated effectiveness at 69%, but was awed by aggregation across studies with
various definitions of condom use, directions of transmission, study designs,
and types of index cases. A subsequent attempt (Pinkerton 1997), controlling
for the direction of transmission, estimated effectiveness at 94%, but was also
awed in that the \sometimes" or \occasional" condom users were
included with \never" users and the analysis also did not control for
study design.
A
new meta-analysis by Davis and Weller (
This
study re-examines available evidence regarding condom effectiveness for
reducing heterosexual transmission of HIV.
O B J E C T I V E S
The
purpose of this review was to estimate condom effectiveness in reducing
heterosexual transmission of HIV, based upon available studies of
serodiscordant heterosexual couples.
C R I T E R I A
F O R C O N S I D E R I N
G S T U D I E S F O R
T H I S R E V I EW
Types of studies
Estimates
of HIV incidence for \always" and \never" condom user groups, must be
obtained from cohort or longitudinal studies of serodiscordant couples. HIV
serology data must be available for two or more points in time: individuals
must have demonstrated seronegativity (HIV-) at the beginning of a time period
and then must be tested again to determine if seroconversion has occurred.
Since
incidence is needed to calculate effectiveness, only longitudinal or cohort
studies were eligible for inclusion.
Types of participants
Studies
ofHIVserodiscordant, sexually active heterosexual couples were eligible. Data
collection focused on seronegative sexual partners of HIV positive index cases
to ensure HIV exposure. Partners had to be seronegative at the beginning of the
observation period and be engaging in penetrative sexual intercourse with the
HIV positive index case. Studies focusing on commercial sex workers were not
considered because of the uncertainty of HIV exposure.
(If
a commercial sex worker used a condom and was not infected with HIV, it is not
clear if the condom provided protection or if the individual was not exposed to
HIV.) Sexual relationships of some duration and monogamy
between partners clarifies the link between the source of exposure and
possible infection. Most studies meeting these latter criteria concern
heterosexuals. Thus, this review focused only on serodiscordant heterosexual
partner studies.
To
ensure only sexual exposure, seronegative partners could not have any nonsexual
HIV risk factors (IDU or receipt of unscreened blood products).
Types of intervention
To
evaluate condom effectiveness, study groups were defined by their reported
condom usage. The only available measure of condom use is by self-report, and
comparisons of the responses of partners show these data to be reliable (Padian
1990, de Boer 1998).
Condom
usage was divided into always, sometimes, and never usage groups. Always-use
indicates that a condom was used for 100% of vaginal penetrative intercourse
acts. Never-use indicates that condoms were not used during any vaginal
penetrative acts (0%). Sometimes-use includes all intermediate estimates of usage
(1-99%) and combinations of never and sometimes (0-99%) or always and sometimes
(1-100%). Since the best measure of condom effectiveness is obtained from a
comparison of always- and never- condom users, only the \always" and
\never" usage groups were used in this review.
Types of outcome measures
The
outcome measures were HIV incidence among always condom users and HIV incidence
among never condom users. HIV status was determined by serology and not
self-report. HIV incidence was calculated from the number of individuals who
seroconverted and the person-years of disease-free exposure time. Thus, the
following information was obtained for the seronegative partners in each study:
the number of seroconversions and the person years of disease-free exposure
time for those who always used a condom; and the number of seroconversions and
the person-years of disease-free exposure time for those who never used a
condom.
Person-years
of disease-free exposure time was calculated from the number of seronegative
partners in a condom use group times the average length of disease-free
exposure time.
S E A R C H S
T R A T E G Y F O R I D E N T I F I C A T I O N O F S
T U D I E S
See:
HIV/AIDS Group search strategy
This
review examined in vivo evidence of condom effectiveness in reducing
heterosexually transmitted HIV. For this review, broad search strategies
(Appendix A) were developed to identify studies in electronic databases and
hand searched reference lists. Abstracts for meetings (unpublished,
non-peer-reviewed data) and international journals were included. The following
electronic databases were used:
AIDSLINE (1980- June 2000) CINAHL (1982-
March 2000) Embase (1974- June 2000) MEDLINE (1966- July Week 4 2000).
M E T H O D S O F T H E R E
V I EW
Inclusion Criteria. Studies had to meet
four criteria for inclusion: (1) examination of sexual transmission of HIV
among serodiscordant heterosexual couples having penetrative sexual
intercourse, (2) longitudinal study design, (3) HIV status determined by
serology, and (4) report on condom usage for \always" and/or \never"
condom users.
Data Collection. This review examined in
vivo evidence of condom effectiveness in reducing heterosexually transmitted
HIV. Peer-review articles, letters to the editor, hand searched reference
lists, and other sources available in June 2000 were located using computerized
databases (MEDLINE, AIDSLINE, Embase, and CINAHL). Sources included abstracts
and international journals.
Criteria for Assessing the Quality of
Studies.
Information regarding condom usage, HIV seroconversion and disease-free
exposure time, and possible confounding variables were recorded from published
descriptions of each study. Because observational studies may be biased by an
unequal distribution of HIV risk factors across study categories, the following
variables were recorded when available: direction of transmission
(male-to-female or female-to-male), date of study and subject enrollment,
source of infection in the index case (IDU, blood product recipient, bisexual,
heterosexual), level of infectivity in the index case, type of condom used
(latex or other type), the presence or history of another STI in the partner,
circumcision in male partners, subtype of HIV, estimates of frequency of sexual
intercourse, length of sexual relationship, age, and country (See data
collection form in Appendix B). Quality of studies was estimated by the detail
and specficity in available data. Specfically, studies that provided actual
person-years of disease-free exposure time were assumed to provide a better
estimate of disease-free exposure time than those studies that only provided
the average length of follow-up time. (Incidence would be underestimated if
average follow-up time included disease-free and diseased periods of time.) Also,
clear information on condom usage (what was asked and how responses were coded
into usage categories) allows for data to be incorporated into the proper
categories for analysis. Two people read, coded, and reached consensus about
each report. In addition, letters were sent to the senior author of each study
with a request to verify the classification of the condom usage data.
Methods of Analysis. Effectiveness was
estimated from the HIV incidence among always users and the incidence among
never users. Incidence was estimated from the number of seroconversions and the
person-years of exposure. Effectiveness could be calculated for studies with
both never (0%) and always (100%) condom users and then combined across
studies.
However,
there are few longitudinal studies that contain both categories of users and
such studies still would need to control for an unequal proportion of different
kinds of index cases (like IDUs) in the two groups. Thus in this review,
incidence was estimated separately for the always and never users from the
total number of seroconversions divided by the total person-years of exposure
across studies. Then, effectiveness was estimated from the two separate
incidence estimates: one minus the ratio of incidence among always users to the
incidence among never users.
Because
aggregations are most reliable when made across homogeneous sample estimates, a
chi-square test was used to test for homogeneity across studies in the
cumulative proportions of partners who had seroconverted and to check for
trends across time. Specifically, the following subgroups were checked for
homogeneity in the cumulative proportion of seroconversions: direction of
transmission (M+F-, F+M-) and source of infection in the index case. Possible
time trends by study enrollment and publication dates were also checked.
Although the chi square test for homogeneity is not very powerful for these
comparisons, it can nevertheless serve as a general indicator of the degree of
heterogeneity. In the case of heterogeneity across different subgroups of
studies, estimates were calculated separately for homogeneous subgroups.
Confidence intervals were constructed for proportions with the binomial
distribution (Fleiss 1981) and for incidence (with time as the unit of
analysis) with the Poisson distribution (Beyer 1966). Effectiveness was
calculated by taking
one minus the ratio of the HIV incidence
among always condom users to that among never condom users. Best- and
worst-case scenarios for effectiveness were calculated using the confidence
interval upper and lower bounds for the two seroconversion rates.
D E S C R I P T I O N O F S T U D I E S
See
Table for a listing of the studies included in the analysis: their
purpose/methods, participants, interventions, and outcomes.
See
Additional Tables for a more detailed listing of the incidence information for
each study. In that table, the first column contains the first author and
publication date for each study, the next four columns provide information on
the \always" user cohorts, and the last four columns provide information
on the \never" user
cohorts. The “Freqs" columns contain the
seroconversion information; the number of seroconversions and the cohort size.
The \Aver" columns contain the average years of disease-free exposure time
per person in the cohort. The \Total p/yrs" column contains the
person-years of exposure time (the product of the number in
the cohort and the average disease-free
observation time). (Note that these tables contain the data used in the
analysis.) There are 13 cohorts of \always" users: 7 provide information
on male-to-female (M+F-) transmission, 3 on female-to-male (F+M-) transmission,
and 3 studies did not specify direction. There are 10 cohorts of \never"
users: 5 provide information on male-to-female (M+F-) transmission, 2 on
female-to-male (F+M-) transmission, and 3 did not specify the direction of
transmission.
M E T H O D O L O G I C A L
Q U A L I T Y
The
preferred method for a meta-analysis of these data would be an analysis of the
original patient data, controlling for possible confounding variables. The
original patient data would contain the disease-free exposure time for each
seronegative partner. In the absence of original patient data, this review uses
aggregate or average disease-free follow-up time in the calculation of
incidence estimates. When those data are explicitly reported in a description
of a partner study, it is assumed that they are accurate. For example, a report
that provides the incidence and/or person-years of disease-free exposure time
would contribute more accurate information to a quantitative summary of
studies. A study that does not report that information specifically,
and instead reports disease-free follow-up time for all patients studied (and
not by the direction of transmission or not by condom usage group) would be
less accurate. A study that does not report disease-free exposure time, and
instead reports average follow-up time, could potentially be even less accurate
if \follow-up time" contains diseased and as well as disease-free
observation periods. The quality of the follow up information is indicated in
the Additional Table.
R E S U L T S
The
electronic searches yielded a total of 4709 references, including duplicates
across databases. MEDLINE yielded 1284 studies, AIDSLINE 2215, CINAHL 265, and
Embase 945. Once imported into Reference Manager v.8.5,
735 studies were identified as duplicates. An unknown number of additional
duplicates were not recognized by Reference Manager and were included in the
remaining 3974 references. The title of each of the 3974 references was read to
determine relevance to our review; 3596 were excluded. For the remaining 378
references, the abstract was read to determine whether study criteria were met.
After reading the abstracts, an additional 203 were eliminated. The full text
of the remining 175 studies was reviewed by the authors to determine the
presence of study criteria. (Three non-English language studies were reviewed
by someone identified by the
There
were 13 cohorts of \always" condom users in the studies that met the
inclusion criteria. The cumulative proportions of partners that seroconverted
were homogeneous across the 7 male to-female cohorts (X2[6]=2.76,p=.84), the 3
female-to-male cohorts (X2[2]=2.54,p=.28), across all 13 cohorts regardless of
the direction of transmission (X2[12]=10.49,p=.57), and across the 10 studies
containing those cohorts (X2[9]=7.77,p=.56). The cumulative proportions of
partners that seroconverted also did not demonstrate a trend across time (X2[1]
trend=2.81, p=.09). Because the studies provided consistent, homogeneous
estimates, incidence was estimated across the cohorts. Across all 13 cohorts
there were 11 seroconversions among 587 \always" users. There was a total of 964.3 person-years of observation time,
approximately 1.6 years per person. The incidence for \always" users
estimated from these data is 1.14 [95% C.I.: .56, 2.04] seroconversions per 100
person-years.
There
were 10 cohorts of \never" users with 40 seroconversions in 276
individuals. Each individual contributed an average of 2.169 years of
disease-free observation. In total there were 598.61 person-years of disease-free
time. In contrast to the \always" users, the cumulative proportions of
partners that seroconverted were significantly different across all 10 cohorts
of \never" users (X2[9]=23.876,p=.005; also
significantly different when the case report by Henry is excluded,
X2[8]=18.282,p=.019). No time trends were present in the data when cohorts were
examined by date of publication (p=.77) or by date of enrollment (p=.78). The
cumulative proportions of seroconversions were significantly different across the
5 male-to-female cohorts (X2[4]=13.947, p=.008; and
without Henry, X2[3]=8.697,p=.034), but not between the 2 female-to-male
cohorts (X2[1]=3.12,p=.078). In fact when studies were categorized by their
characteristics (direction of transmission, index case source of infection,
continent where the study was located, length of follow-up time), the largest
homogeneous category of studies consisted of the group of studies with the
longest follow-up time (X2[4]=9.0,p=.06). The follow-up time for these five cohorts
was longer than the average follow-up time (2.169
years)
for ”never" users. Four of the _ve cohorts are
studies of partners of transfusion recipients or hemophiliacs (studies by van
der Ende 1988, Peterman 1988, and O'Brien 1994); the fifth is a cohort in the
Allen (1992) study. The cumulative proportions of seroconversions in these five
cohorts were not significantly different (X2[3]=3.43,p=.33;
merging the two cohorts reported in Peterman, X2[2]=1.89,p=.39). The
transfusion/hemophiliac studies may also have the fewest confounding variables
present (STDs, possible IDU) and may represent the same subtype of HIV.
Incidence across all cohorts of \never" users is 6.68 [95% C.I.: 4.78,
9.10] per 100 person-years. In the transfusion/hemophiliac studies there were
12 seroconversions among 84 people (236.4 person-years) with an incidence of
5.08 [95% C.I.: 4.78, 8.88] per 100 person-years. In the transfusion/hemphiliac
studies and the Allen F+M- cohort (the five cohorts with the longest follow-up
time), there were 14 seroconversions among 87 people (243.3 person-years) with
an incidence of 5.75 [95% C.I.: 3.16, 9.66] per 100 person-years for non-condom
users.
Condom effectiveness was then estimated
from the incidence of HIV among \always" users and the incidence among
\never" users.
A single, homogeneous estimate of
incidence was found for the cohorts of \always" users (1.14), but
selection of a \best" estimate for \never" users is more difficult.
Effectiveness for reducing sexual transmission of HIV is 82.9% when the overall
incidence for \never" users is used (6.68), in spite of the notable
heterogeneity among the cohorts. Effectiveness was 77.6% for the subgroup of
transfusion/hemophiliac cohorts and 80.2% when incidence among \never"
users was estimated with cohorts that had longer than average follow-up time
(5.75). A best case and worst case scenario was also estimated using the lower
and upper limits of the confidence intervals for the incidence estimates. A
best case scenario, using the lower confidence limit for the incidence with
always condom use and the upper confidence limit for the non-condom users,
estimated effectiveness at 94.2%. A worst case scenario,
using the upper confidence limit for the always users and the lower limit for
the never users, estimated effectiveness at 35.4%.
Thus,
effectiveness is approximately 80.2%, but may be as low as 35.4% or as high as
94.2%.
D I S C U S S I O N
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, nor did they
report on the quality of the condoms used, 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.
The
set of cohort studies remains essentially the same as in the
This
review used two separately pooled incidence rates to estimate effectiveness
rather than pooling relative risks across studies. Comparison of condom usage groups
within the context of a single study could control for some extraneous
confounding variables, especially if the study used multivariate modeling
controlling for HIV risk factors and reported the adjusted relative risk for
condom usage. Four articles reported both always and never user cohorts (Van
der Ende 1988, Allen 1992, Siddiqui 1992, Deschamps 1996), but none reported a
relative risk controlling for HIV risk factors. A serious problem in estimating
effectiveness is the bias that may be present in the two condom usage groups.
When condom use is associated with any other HIV risk factor, the groups will
be biased and effectiveness may be over- or underestimated. If a true
experiment had been conducted (a randomized controlled trial) in which individuals
had been randomly assigned to 100% condom use or 0% condom use (and they were
instructed to have sexual intercourse with an HIV+ partner), condom usage would
be independent of HIV risk factors (because the risk factors would be
distributed similarly within each usage category). Such an experiment would not
be ethical, but parallel conditions (condom usage should be uncorrelated with
HIV risk factors) must exist in an observational study in order to obtain an
unbiased estimate of effectiveness and it is clear that condom use is now
inuenced by many factors. In longitudinal studies, repeated office visits with
HIV blood tests, interviewing, and counselling cause a significant increase in
condom usage (Deschamps 1996, van der Ende 1988, Kamenga 1991, Allen 1992,
Fischl 1987) and abstinence (Deschamps 1996, Kamenga 1991, De Vincenzi 1994,
Fischl 1987). The condom non-user group is now a condom refuser group:
individuals who knowingly have sex with an HIV-infected partner and, despite
continued counseling, refuse to use condoms. Condom non-users are more likely
to use drugs and alcohol (Skurnick 1988, Kennedy 1993). The bias inherent in
the condom use groups makes it difficult to find an appropriate and
minimally-biased comparison group to serve as a denominator for the estimation
of effectiveness.
In
this study, we attempted to deal with the difficulty of finding a proper
denominator by estimating effectiveness from two separate estimates of
incidence (with and without condoms) and exploring several possible denominators.
It is interesting to note that the 13 cohorts of always users (n=587) provided
a homogeneous estimate of incidence, while the 10 never user cohorts (n=276)
exhibited significant heterogeneity in spite of the much smaller sample size.
The
significantly different proportions of seroconversions in the
condom nonuser cohorts suggests that there may be different rates of HIV
transmission in those cohorts. While the presence of other STIs, different
subtypes of HIV, and/or different proportions of IDUs in the cohorts could
cause higher transmission rates, over-estimation of incidence among nonusers
would lead to an over-estimation of condom effectiveness. It could be argued
that HIV negative partners in the early hemophiliac and transfusion cohort studies
might serve as the best \historical control" cohorts, especially for
condom nonusers. These groups may provide a more accurate estimate of the HIV
transmission rate since they generally had no additional HIV risk factors and
condom use in some of the older studies was for contraception and not for HIV
prevention. This group of cohorts (van der Ende 1988, Peterman 1988, O'Brien
1994) plus the cohort in Allen (1992) were found to be homogeneous and to have
a longer than average follow-up time.
This
review is limited by the lack of detail in published reports concerning condom
usage information and disease-free exposure time. Although reporting of condom
use by individuals appear to be reliable (deBoer 1998, Padian 1990, Upchurch
1991, James 1991), rarely do investigators provide detail on the assessment
of condom usage. Most investigators
carefully report how HIV status was determined, but do not provide similar
detail regarding condom usage. A serious limitation in assessing condom usage
in a review of this type lies in the failure of published reports to state what
question(s) was asked, how responses were coded, and how responses were
recategorized. Terms such as \regular," \consistent,"
\systematic," and \routine" were used in original reports without a
clear definition.
Another
limitation is the availabiity of accurate information on the disease-free
exposure time. Use of the average length of follow-up time to calculate
incidence rather than the exact number of seronegative person-years
underestimates incidence. For example, in the Fischl et al study their reported
24 month median length of follow up time may be 12 months of seronegative time,
since half of the sexually active individuals seroconverted at or before 12
months (according to their table).Re-estimation of their incidence and
confidence interval with 12 instead of 24 months average follow up, causes the
incidence rate to increase and the study becomes even more of an outlier. If
incidence is underestimated by different amounts in each condom user group,
effectiveness may be over- or underestimated.
To
clarify ambiguities in reported information concerning condom usage and
disease-free exposure time, letters were sent to the authors of each study.
Authors were asked to verify that information taken from their article were coded accurately and if the original data might still
be available for analysis. Replies have been received from Feldblum (Hira
1997), Peterman (1988), and Makuch (Siddiqui 1992) confirming the coding of
their data. The inquiry to Ryder (Kamenga 1991) was returned unopened and a
reply from Lambert (Laurian 1989) indicates Laurian has changed affiliations.
No other responses have yet been received, but when and if responses are
received the review will be updated.
A U T H O R S ' C O N C L U
S I O N S
Implications for practice
Consistent
condom use is effective in reducing sexual transmssion of HIV, but does not
eliminate the risk of HIV transmssion.
Consistent
use is de_ned as using a male condom for all acts of penetrative vaginal
intercourse. Condom effectiveness is similar to, but somewhat less effective,
than for pregnancy.
Implications for research
Estimates
of condom effectiveness for reducing HIV transmission can be improved, even
though direct estimation of efficacy is impossible to estimate. Design of new
studies will not reduce the difficulty of estimating condom efficacy as condom
use is now inextricably confounded with HIV risk factors. Individuals who
knowingly have unprotected, penetrative sex with an HIV+ partner after being
advised to abstain or use protection (condoms) are at-risk for other HIV risk
factors. Perhaps a cohort of serodiscordant couples, for example of
hemophiliacs, can be located from early in the HIV epidemic (say in the early
1980s) to create an historical control cohort. Detailed analysis of original
patient data may also improve estimates of effectiveness. Effort at improving
the coding of condom usage and estimation of disease-free exposure time would
improve the accuracy of effectiveness estimates.
Future
couple studies need to be as careful about asking about and reporting condom
usage as they are about serological determination of HIV status. Questions
should be asked in the most reliable way possible and coding of responses
should be reported.
A C K N OWL E D G E M E N T
S
This
review is based in part upon the article by Davis and Weller that appeared in
Family Planning Perspectives (1999, 31:272-279).
P O T E N T I A L C O N F L I C T O F I N T E R E S T
None. (No other private or federal funding
related to condoms or condom use.)
S O U R C E S O F S U P P O
R T
External sources of support
_ The Population Council,
Horizons Project
Internal sources of support
_ No sources of support
supplied
R E F E R E N C E S
References to studies included in this review
Allen 1992 ¯published data only´ Allen S, Tice J, Van
de Perre P, Seru_lira A, Hudes E, Nsengumuremyi F, et al. Effect of serotesting
with counselling on condom use and seroconversion
among HIV discordant couples in Africa. British Medical
Journal 1992;304:1605{1609.
Deschamps 1996 ¯published data only´ Deschamps M, Pape JW,
Hafner A, Johnson WD. Heterosexual Transmission of HIV
in
deVincenzi (ESG)1994 ¯published data only´ de Vincenzi I, for
the European Study Group onHeterosexual Transmission of HIV. A
Longitudinal Study ofHuman Immunodeficiency Virus Transmission
byHeterosexual Partners. TheNew
Fischl 1987 ¯published data only´ Fischl MA,Dickinson
GM, Scott GB, Klimas N, Fletcher MA, Parks W. Evaluation of
Heterosexual Partners, Children, and Household Contacts of Adults
with AIDS. Journal
of the American Medical Association
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Henry 1991 ¯published data only´ Henry, K. Documented
male-to-female transmission of HIV-1 after minimal vaginal exposure in the
absence of other cofactors for infection.
Hira 1997 ¯published data only´ Hira SK, Feldblum PJ,
Kamanga J, Mukelabai G,Weir SS, Thomas JC. Condom and Nonoxynol-9 Use and the Incidence of HIV Infection in
Serodiscordant Couples in
Kamenga 1991 ¯published data only´ Kamenga M, Ryder RW,
Jingu M, Mbuyi N, Mbu L, Behets F, et al. Evidence ofMarked
Sexual Behavior Change AssociatedWith HIV-1 Seroconversion in 149
Married Couples With Discordant HIV-1 Serostatus:
Experience at an
Laurian 1989 ¯published data only´ Laurian Y, Peynet J,
Verroust F. HIV Infection in Sexual Partners of HIV-Seropositive
Patients With Hemophilia. The
Musicco (ISG) 1994 ¯published data only´ Musicco M, Lazzarin
A,Nicolosi A, Gasparini M, Costigliola P, Arici C for the Italian
Study Group on HIV Heterosexual Transmission.
Antiretroviral
Treatment ofMen InfectedWith Human Immunodeficiency Virus Type 1 Reduces the
Incidence of Heterosexual Transmission. Archives of Internal
Medicine 1994;154:1971{1976.
O'Brien 1994 ¯published data only´ O'Brien TR, Busch MP,
Donegan E, Ward JW, Wong L, Samson SM, et al.
Heterosexual Transmission of Human Immunodeficiency
Virus
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Partners. Journal
of Acquired Immune De_ciency Syndromes 1994;7:705{710.
Peterman 1988 ¯published data only´ Peterman TA,
Stoneburner RL, Allen JR, Jaffe HW, Curran JW. Risk of Human
Immunode_ciency Virus Transmission From Heterosexual
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the AmericanMedical
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Saracco (ISG)1993 ¯published data only´ Saracco A,Musicco M,
NIcolosi A, Angarano G, Arici C, Gavazzeni G, et al.Man-To-Woman
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Partners of Infected Men. Journal of Acquired Immune De_ciency
Syndromes 1993;6:497{502.
Siddiqui 1992 ¯published data only´ Siddiqui NS, Brown
LS, Phillips RY, Vargas O, Makuch RW. No Seroconversions Among Steady Sex Partners of Methadone-Maintained HIV-1-Seropositive
Injecting Drug Users in
van der Ende 1988 ¯published data only´ van der Ende ME,
Rothbarth P, Stibbe J. Heterosexual Transmission of HIV by
Haemophiliacs. British Medical Journal 1988;297:1102{ 1103.
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Jingu 1993 ab Jingu M, Mbuyi N,
Ndilu N, Assina Y, Musungayi L. Impact of Prolonged Condom Use
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Kamps 1989 ab Kamps BS, Niese D,
Brackmann HH, Euler P, van Loo B, Kamradt T. No more
seroconversions among spouses of patients of the
Laye 1998 ab Laye C, Maposhere C,
McFarland W, Mbizvo M, Katzenstein D, Parsonnet J.High
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Buccolero G, De Gennaro M, Angarano G, Pastore G. Ef_cacy of
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Massimo 1992 ab Massimo M, Angarano G, Saracco A, et al. Antiretroviral
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Moss 1992 ab Moss G, Clemetson D,
D'Costa LJ, et al. Despite Safer Sex Practices After Counselling,
Seroconversion is High Among HIV Serodiscordant Couples in
Musicco 1992 ab Musicco M, Saracco A,
Nicolosi A, et al. Assessment of Incidence and Risk Factors for
Male to Female HIV Transmission. Int Conf AIDS.
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Musicco 1993 ab Musicco M, Saracco A,
Nicolosi A, Gasparini M, Arici C, Lazzarin A, for the Italian
Partner Study. The percentage of risk attributable to sexual
behavior and to man's infectiousness in man to woman sexual transmission
of HIV-1. Abstracts IXth International Conference on AIDS.
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Nastiff 1998 ab Nastiff VM, Beltran
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O'Brien 1993 ab O'Brien TR, Busch MP,
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Operskalski 1997 Operskalski EA, Stram
DO, Busch MP, et al. Role of Viral Load in Heterosexual
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Padian Padian NS, Obrien TR, Chang Y, Glass S,
Francis DP. Prevention of Heterosexual
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Heterogeneous Male-to-Female Transmission of Human
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Padian 1997 Padian NS,
Papetti Papetti C, Pesce AM, Mezzaroma I, et al.
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Papetti 1992 ab Papetti C, Mezzaroma
I, D'Of_zi GP, et al. Risk Factors for Heterosexual Transmission of HIV-
Papetti ab Papetti C, Mezzaroma
I, D'Of_zi GP, Valdarchi C, Pinter E, et al. High prevalence of
HIV heterosexual transmission in one hundred stable couples. Int
Conf AIDS. 6:101{123.
Saracco 1989 ab Saracco A. HIV
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Serwadda 1995 Serwadda D, Gray RH,
Wawer MJ, et al. The Social Dynamics of HIV Transmission as
Reected Through Discordant Couples in Rural
Sion Sion FS, Santos EA, Salerno-Gon, Calves R,
et al. Lack of female to male transmission in
husbands of HIV infected women. Int Conf AIDS 6:266{23.
Sion 1992 ab Sion FS, Signorini
DJ, Santos EA, et al. Absence of Female-to-Male Transmission of HIV
in Stable Couples in Rio de Janeiro, Brazil. Int Conf
AIDS. 1992;8:C273{24.
Skurnick 1995 ab Skurnic JH, Bromberg
J, Kennedy C, Sheffet A, Louria DB. Couples' Practice of Safe Sex After Knowledge of HIV Discordance: A Women's Report From
the Heterosexual Transmission Study (HATS). HIV Infect
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Tice ab
Tice
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on Condoms/Spermicide Use Among HIV Discordant Couples in Africa. Int Conf AIDS. 6:262{23.
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Muga R, et al. HIV Transmission in Heterosexual Partners of Intravenous
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Additional references
Beyer 1966 Beyer WH. CRC Handbook of Tables
for Probability and Statistics.
CDC 1988 Centers for Diesease Control. Condoms for prevention of sexually transmitted diseases.
MMWR
1988;37:133{137.
CDC 1993 Centers for Disease Control. Update:
Barrier protection against HIV infection and other
sexually transmitted diseases. MMWR 1993;42: 589-591,597.
Fleiss 1981 Fleiss JL. StatisticalMethods for
Rates and Proportions.New York: John Wiley & Sons,
1981.
Glass 1974 Glass R, Vessey M, Wiggins P. Use-effectiveness of the condom in a selected family
planning clinic population in the
Grady 1986 GradyWR,HaywardMD,Yagi J. Contraceptive failure in theUnited States: Estimates
from the 1982 National Survey of Family Growth. Family Planning
Perspectives 1982;14:68{74.
Hatcher 1998 Hatcher RA, et al. Contraceptive
Technology. 17 Edition.
James 1991 James NJ,Bignell CJ,Gillies PA. The relisbility of
self-reported sexual behavior. AIDS 1991;5:333{336.
Jones 1992 Jones EF, Forrest JD.
Contraceptive failure rates based on the 1988 NSFG.
Family
Planning Perspectives 1992;24:12{19.
Kennedy 1993
Padian 1990 Padian NS. Sexual Histories of
Heterosexual Couples with One HIV Infected Partner. AJPH 1990;80(8):990{991.
Padian 1997 Padian NS, et al. Heterosexual
transmission of human immunodeficiency virus (HIV) in
Pinkerton 1995
Pinkerton 1997
Ross 1988 RossMW. Personality
factors that differentiate homosexualmen with positive and negative
attitudes toward condom use.
Schirm 1982 Schirm AL, et al.
Contraceptive failure in the
Skurnick 1998 Skurnick JH, et al.Maintenance of safe sex behavior by HIV-serodiscordant
heterosexual couples. AIDS Educ and Prevention 1998;10: 493{505.
Surgeon General Surgeon General. Condom use for prevention of sexual transmission of
HIV infection. JAMA 1993;269:2840.
Trussel personal Trussel, J. The
likelihood of pregnancy with or without a condom is actually a
probability and must be transformed into a rate. Thus effectiveness is: 1-(-ln
- fc)/ (-ln- f0) where fc indicates the likelihood of pregnancy with a
condom and f0 is the likelihood without a condom.
Trussell 1987 Trussel J,Kost K. Contraceptive failure in theUnited States:
Acritical review of the
literature. Studies
Fam Plan 1987;18:237{283.
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Shepard M, Brookmeyer R, Fox R, et al. Interpartner
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1991;134(10):1159{66.
Weller 1993
T A B L E S
Characteristics of included studies
Study Allen 1992
Methods
Prospective study of sexually active HIV discordant heterosexual couples
(incidence estimation and associated risk factors)
Participants
-
-
enrolled in 1988
-
M+F- couples (n=30)
-
F+M- couples (n=23)
-
IC type: heterosexual
- partner exclusions: none
Interventions
- counselling (educational video about AIDS & discussion group led by a
social worker)
- free latex condoms & spermicidal suppositories
- free health care
- @
3mo sex practices, HIV serotest
- @
6mo medical history
- @
12mo physical exam
Outcomes
Vaginal condom usage
- every time (100%)
- sometimes (1-99%)
- never (0%)
HIV
serotesting by ELISA, confirmed by Western blot
Notes
- some male partners not monogamous
- some male partners circumcised, some not
- spermicide use
Allocation
concealment D
Study Deschamps 1996
Methods
Prospective study of sexually active HIV discordant heterosexual couples (incidence
estimation and associated risk factors)
Participants
- Port-au-Prince, Haiti, National Institute for Laboratory Research (sole
source of free testing for HIV in
-
enrolled 1/88- 7/92
-
M+F- couples (n=143)
-
F+M- couples (n=34)
-
IC type: heterosexual
- partner exclusions: homosexuals, bisexuals, IVDU, blood
transfusion in past 5 years
Interventions
- counselling about HIV and safe sex
- free latex condoms
- @
3mo HIV serotest
Outcomes
Vaginal (and possibly anal) condom usage
-
\used for every sexual act" (100%)
- occasionally (1-99%)
- never (0%)
HIV
serotesting by ELISA, con_rmed by Western blot
Notes
- STDs in partners
Allocation
concealment D
Study Fischl 1987
Methods
Prospective study of HIV transmission to household members (including sex
partners)
Participants
- United States, university medical center in FL
-
enrolled 1/83- 6/85
-
M+F- couples (n=18)
-
F+M- couples (n=6)
-
IC type: IVDU, heterosexual, bisexual, transfusion, hemophiliac, unknown
-
partner exclusions: those with \an independent risk factor"
Interventions
- @ 4-6 mo medical history, sexual practices, physical exam, lab tests (inc.
serotest for HTLV-III/LAV)
Outcomes
Vaginal condom usage
- routine use (100%)
- intermittent/ never (0-99%)
HIV
serotesting by radioimmunoprecipitation and enzyme immunoassay, con_rmed by
Western blot
Notes
- all of the index cases had AIDS
Allocation
concealment D
Study Henry 1991
Methods
Case report (n=1) of male-to- female HIV transmission
Participants
-
-
1990
-
M+F- couple (n=1)
-
IC type: IVDU bisexual
Interventions
- HIV test results available for 1988- 1990
Outcomes
HIV serotesting by EIA, con_rmed by Western blot
Notes
- because this is a case report, it may be an unusual observation
Allocation
concealment D
Study Hira 1997
Methods
Prospective study of sexually active HIV discordant heterosexual couples
(incidence estimation and associated risk factors)
Participants
-
- enrolled 1988- 1992
-
M+F- couples (n=80)
-
F+M- couples (n=30)
-
IC type: heterosexuals attending an STD clinic
- partner exclusions:
Interventions
- counselling to use condom and spermicide together
- free latex condoms and spermicidal products
- @
3mo contraceptive counselling, physical exam, STD tests, HIV test, coital log
Outcomes
Vaginal condom usage
- always (100%)
- sometimes/ never (0-99%)
HIV
serotesting by ELISA, con_rmed by Western blot
Notes
- spermicide (N-9) use
-
STDs in partners
- majority of men not circumcised
- each sex act considered independently
Allocation
concealment D
Study Kamenga 1991
Methods
Prospective study of sexually active HIV discordant heterosexual couples
(incidence estimation and associated risk factors)
Participants
-
- enrolled 1987- 1988
-
M+F- couples (n= 79)
-
F+M- couples (n=69)
-
IC type: heterosexual factory and bank employees
- partner exclusions: none
Interventions
- \intensive" counselling about STDs, HIV, and condoms use
- free condoms w/ spermicidal lubricant
- @
1mo coital log, counselling
- @
6mo physical exam, venipuncture, GYN exam
Outcomes
Vaginal (and possibly anal) condom usage
- always (100%)
- some/never (0-99%)
HIV
serotesting by ELISA, con_rmed by Western blot
Notes
- some male partners uncircumcised
-
STDs in partners (low prevalence)
- index cases are not IVDUs
-
suspected improper use among some seroconverters, but not reported for all
Allocation
concealment D
Study Laurian 1989
Methods
Prospective study of sexually active HIV discordant heterosexual couples (and
associated risk factors)
Participants
-
-
enrolled 10/85- 10/87
-
M+F- couples (n=31)
-
IC type: hemophilia
- partner exclusions: ?
Interventions
- counselling
- @
6mo counselling, HIV antibody and antigen tests
Outcomes
Vaginal (and possibly anal) condom usage
- always (100%)
- some/never (0-99%)
HIV
antibody and antigen tested by ?
Notes
Allocation
concealment D
Study Musicco (ISG) 1994
Methods
Prospective study of sexually active HIV discordant heterosexual couples
(incidence estimation and associated risk factors)
Participants
-
-
enrolled 2/87- 5/92
-
M+F- couples (n=436)
-
IC type: IVDU (predom.)
- partner exclusions: IVDU, prositutes, recipients of blood
products
Interventions
- counselling about HIV prevention, condom use, GYN exams
- @
6mo sexual history, STD history, contraceptive history, HIV test
Outcomes
Vaginal (and possibly anal) condom usage
- always (100%)
- not always/ never (0-99%)
HIV
serotesting by immunoenzymatic method, con_rmed by Western blot
Notes
- some ICs underwent zidovudine treatment (and had lower transmission)
- each time exposure considered independent (each person mihgt
contribute to each category of condom use/ exposure time)
Allocation
concealment D
Study O'Brien 1994
Methods
Retrospective cohort study of HIV discordant heterosexual couples (incidence
estimation and associated risk factors)
Participants
-
- enrolled 1987- 1992
-
M+F- & F+M- couples (n=
-
IC type: transfusion after 1978
- partner exclusions: none necessary (no other risk factors
present)
Interventions
- counselling about HIV
- @
6mo medical history, sexual history, counselling, HIV serotest
Outcomes
Vaginal condom usage
- all (100%)
- most but not all (1-99%)
- never (0%)
HIV
serotesting by enzyme immunoassay (EIA), con_rmed by Western blot
Notes
- date of transfusion known
Allocation
concealment D
Study Peterman 1988
Methods
Retrospective cohort study of sexually active HIV discordant heterosexual
couples (incidence estimation and associated risk factors)
Participants
-
-
enrolled 1987
-
M+F- couples (n=55)
-
F+M- couples (n=25)
-
IC type: transfusion after 1978
- partner exclusions: those with other HIV risk factors
Interventions
- none (look-back study)
Outcomes
Vaginal (and possibly anal) condom usage
- ever used (1-99%)
- never (0%)
HIV
serotesting by enzyme- linked immunosorbent assay, con_rmed by Western blot
Notes
- date of transfusion known
- follow-up reported for IC transfusion to IC HIV-diagnosis
Allocation
concealment D
Study Saracco (ISG)1993
Methods
Prospective study of sexually active HIV discordant heterosexual couples
(incidence estimation and associated risk factors)
Participants
-
-
enrolled 2/87- 5/91
-
M+F- couples (n=305)
-
IC case: IVDU (predom.)
- partner exclusions: those with other HIV risk factors
Interventions
- counselling about HIV, condom use, advise to remove
IUDs
- @
6mo sexual & medical history, HIV serotest
Outcomes
Vaginal (and possibly anal) condom usage
- always (100%)
- not always (1-99%)
- never (0%)
HIV
serotesting by ELISA, con_rmed by Western blot
Notes
Allocation
concealment D
Study Siddiqui 1992
Methods
Prospective study of sexually active HIV discordant heterosexual couples
(incidence estimation and associated risk factors)
Participants
-
-
enrolled 12/88- 10/91
-
M+F- couples (n=16)
-
F+M- couples (n=6)
-
IC case: IVDU (only) on methadone maintenance
- partner exclusions: IVDU
Interventions
- counselling
- @
3-4mo sexual & medical history, HIV serotest
Outcomes
Vaginal condom usage
- every time (100%)
- intermittent (1-99%)
- none (0%)
HIV
serotesting by ?
Notes
- 3 partners had STDs
- 2
couples had anal sex 1.9 times/mo
Allocation
concealment D
Study deVincenzi (ESG)1994
Methods
Prospective study of sexually active HIV discordant heterosexual couples
(incidence estimation and associated risk factors)
Participants
- 8 countries in European Community, hospital wards, outpatient clinics, STD
clinics, public health departments
-
enrolled from 3/87- 3/91
-
M+F- couples (n=157)
-
F+M- couples (n=88)
-
IC type: IVDU (predom.), transfusion, bisexual, heterosexual
- partner exclusions: IVDU, male homosexuals, recipients of
unscreened blood products, multiple sexual partners, one or more sexual
partners from sub-Saharan
Interventions
- counselling about HIV and safe sex
- @
6mo counselling, HIV serotest, sexual history
Outcomes
Vaginal and anal condom usage
- always (100%)
- inconsistent (0-99%)
HIV
serotesting by ELISA, confirmed by Western blot or radioimmunoprecipitation
Notes
- \always" users were those who used condoms for all vaginal AND anal
contacts
-
STDs in partners
Allocation
concealment D
Study van der Ende 1988
Methods
Prospective study of heterosexual hemophiliacs and their partners
Participants
-
-
enrolled 1984
-
M+F- couples (n=13)
-
IC case: hemophilia
- partner exclusions: none (no other risk factors present)
Interventions
- @ 3mo blood screened for cell counts, liver enzyme activity, cytomegalovirus,
Epstein-Barr virus, and HIV
- @
6mo lymphocyte counts and lymphocyte stimulation tests
Outcomes
Vaginal condom usage
- always (100%)
- sometimes (1-99%)
- never (0%)
HIV
antibody confirmed by immunoblotting
Notes
- 7/13 had Walter Reed stages IV or V, \progressive disease"
Allocation
concealment D
Characteristics of excluded studies
Cameron
1989 ab insufficient information on the entire sample
Feldblum
1992 ab insufficient information (see Hira 1997)
Feldblum
ab insufficient information on condom use and seroconversions
Flepp
not received
Guimaraes
ab insufficient information on condom use and seroconversions
Hira
1989 ab Hira 1997 has a larger cohort
Jingu
1993 ab insufficient information
Jingu
ab insufficient information on condom use and seroconversions
Kamenga
1989 ab Kamenga 1991 more recent
Kamps
1989 ab insufficient information on follow-up time
Laye
1998 ab insufficient information on condom usage
Lo
1992 ab insufficient information on condom use and seroconversions
Mandelbrot
1997 Insufficient information on exposure time
Massimo
1992 ab More information in Musicco 1994
Moss
1992 ab insufficient information on condom use and seroconversions
Musicco
1992 ab More detail in Saracco 1993;
Musicco
1994 Musicco 1993 ab More detail in Saracco 1993; Musicco 1994
Nagachinta
ab insufficient information on condom use and seroconversions
Nastiff
1998 ab insufficient information on condom use and seroconversions
O'Brien
1993 insufficient information on condom usage
O'Brien
1993 ab insufficient information on condom usage
Operskalski
1997 insufficient information on condom usage
Padian
insufficient information on condom usage
Padian
1989 ab insufficient information on condom usage and seroconversion
Padian
1997 insufficient information on condom usage
Papetti
insufficient information on condom usage
Papetti
1992 ab insufficient information on condom use and seroconversions
Papetti
ab insufficient information on seronegative partners (see Papetti 1992)
Saracco
1989 ab insufficient information
Serwadda
1995 insufficient information on condom usage
Sion
insufficient information on total exposure time to index case
Sion
1992 ab insufficient information on condom usage
Skurnick
1995 ab insufficient information on seroconversions
Tice
ab insufficient information on condom use and seroconversions
Tor
1992 ab insufficient information on condom usage
al Nozha not received
A D D I T I O N A L
T A B L E S
Table 01. Incidence rate
information by study
. . .
I N D E X T
E R M S
Medical Subject Headings (MeSH)
Cohort
Studies; Condoms [standards]; Disease Transmission, Horizontal; Evaluation
Studies; HIV Infections [prevention & control]; HIV Seronegativity; HIV
Seropositivity; Heterosexuality
Medical MeSH check words
Female;
Humans; Male
C O V E R S H E E T
Title Condom effectiveness in reducing heterosexual HIV
transmission
Authors Weller S, Davis, K
Contribution of author(s) Karen R. Davis: search for and identify
studies, read and abstract information from studies, table information from
studies, write-up description of methods.
Susan
C. Weller: read and abstract information from studies, analyse information from
studies, write-up findings and discussion, send letters to PIs of original
studies.
Issue protocol first published /
Review _rst published /
Date of most recent amendment 20 May 2004
Date of most recent
SUBSTANTIVE amendment
19
November 2001
What's New Information not supplied by author
Date new studies sought but none found
Information
not supplied by author
Date new studies found but not yet included/excluded
Information
not supplied by author
Date new studies found and included/excluded
Information
not supplied by author
Date authors' conclusions
section amended
Information
not supplied by author
Contact address Susan Weller
Telephone:
409 772 – 2551 E-mail: sweller@utmb.edu
Facsimile: 409 772 - 2573
DOI 10.1002/14651858.CD003255
Cochrane Library number CD003255
Editorial group Cochrane HIV/AIDS Group
Editorial group code HM-HIV
C O M M E N T S
A N D C R I T I C I S M S
Condom effectiveness in reducing heterosexual HIV
Summary
Why
aren't the data presented as time to event? Is this a limitation of the way the
results were presented? Even if considering the outcome as binary rather than
time to event is justified could you explain why the numerators and
denominators have been simply summed across trials, which is considered wrong
for RCTs? It is usual to apply a weighting scheme such that the trials
containing the most information receive the most weight.
Author's
reply The data are indeed presented as the average
length of disease-free follow up time. That is necessary to estimate incidence.
For each study the following are reported: the cohort size, the number of
subjects who seroconverted, and the average disease-free follow-up time.
This
information is reported for those who used and for those who did not use
condoms. A limitation is that this information is available only in the
aggregate for each study and not for individual subjects. Cohort results are
combined relative to their sample sizes and are not weighted equally.
Contributors S.Weller.
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