Implications for HIV prevention programs from a serobehavioural survey of men who have sex with men in Vancouver, British Columbia: The ManCount study.
Moore, David M. ; Kanters, Steve ; Michelow, Warren 等
Gay, bisexual and other men who have sex with men (MSM) remain the
population most heavily affected by HIV in Canada and British Columbia
(BC). (1,2) MSM are thought to comprise 45% or more of the estimated
9,300-13,500 individuals infected with HIV in BC. (3,4) The number of
new diagnoses of HIV among MSM in BC has remained largely unchanged
since 2003, with approximately 150-180 new diagnoses each year. (4)
We conducted an analysis from an HIV serobehavioural survey of MSM
who attend community venues that cater to gay, bisexual and other MSM in
Vancouver in order to determine the current state of HIV knowledge and
HIV risk and preventive behaviours among this population.
METHODS
The Public Health Agency of Canada (PHAC) has developed a national
enhanced surveillance system for HIV among MSM called M-Track. In
Vancouver, M-track was called "The ManCount Survey" and was
jointly designed and implemented by PHAC and local partner
organizations. The study protocol was approved by the Research Ethics
Boards of the University of British Columbia and Health Canada.
Participants were recruited from August 1, 2008 to February 28,
2009 through venues that cater to gay, bisexual and other MSM. We used a
time-space sampling recruitment methodology based on a two-stage
sampling plan. This entailed the construction of a sampling frame of
potential recruitment events at participating venues followed by
developing a standardized process for sampling these events and venues.
Men [greater than or equal to] 18 years of age who reported ever
having had sex with other men were offered enrolment in the study.
Participants were excluded if they had previously completed the survey
or were unable to complete the questionnaire in English. After providing
informed consent, participants completed an anonymous self-administered
questionnaire and provided an anonymous dried blood spot (DBS) sample.
HIV testing was performed on the DBS using the Bio-Rad GS rLAV HIV-1 EIA
assay. Confirmatory testing was performed using the Bio-Rad Genetic
Systems[TM] HIV-1 Western Blot assay.
The questions included a core set, proposed by PHAC, for inclusion
in all M-Track surveys, as well as questions that were developed
locally. Unless otherwise stated, percentages are expressed from the
total of respondents who answered a particular question or set of
questions. We examined trends in HIV seropositivity and differences in
the awareness of HIV seropositivity across age categories using the
Cochran-Armitage test of trend and Fisher's exact test,
respectively. We compared the responses to key variables with
participants classified on the basis of their HIV serostatus by DBS and
by self-report using Chi-square and Fisher's exact tests.
RESULTS
A total of 2,805 individuals were approached for study
participation and 1,169 (41.7%) were enrolled. Of these, 1,138 (97.3%)
provided DBS samples which were suitable for testing. Participants were
recruited from bars (54%), followed by community events (25%),
businesses (12%), community associations (4.9%), and bathhouses (4.2%).
Most participants (76%) reported European/North American ethnicity; 6.6%
Asian; 4.0% Aboriginal; and 14% other. The median age was 33 years
(inter-quartile range [IQR]: 26-44) and 79% had completed some
post-secondary education. A total of 81% identified as being gay or
homosexual; 11% bisexual; 3.0% two-spirited; 2.3% queer; and 1.8%
straight.
Overall, 206/1,138 (18%; 95% CI 16-20) were HIV-positive by DBS. Of
these, 202 self-reported their HIV status and 86% were aware they were
positive. HIV seropositivity increased with age from 7.1% for men <30
years of age to 19% for those 30-44 years, and 34% for those [greater
than or equal to]45 years (p<0.001 for test of trend) (Figure 1).
However, the proportion of HIV-positive men aware of their serostatus in
each age group varied greatly, from 53% (16/30) among those aged <30
to 85% (74/87) among those aged 30-44 years, and 94.3% (93/98) among
those aged [greater than or equal to]45 years (p<0.001).
Among HIV-positive individuals who were aware of their serostatus,
the median year of diagnosis was 1997 (IQR: 1989-2003). Approximately
70% reported taking anti-HIV medication in the previous six months (an
additional 8.7% reported having used these medications in the past).
Of the participants who provided a DBS, 933 (82%) self-reported
their status as HIV-negative/unknown. Of these, 28 (3.0%) tested
HIV-positive by DBS, which represented 14% of the positive tests. Among
participants who self-reported as HIV-negative or unknown, 86% reported
ever having been tested for HIV. Among those aged <30 years, 77%
reported ever testing versus 89% for those aged 30-44 years, and 85% for
those aged [greater than or equal to] 45 years. Of the 882 men who were
HIV-negative/unknown by self-report, 601 (68%) reported testing in the
previous two years. Twenty (71%) of 28 individuals with undiagnosed HIV
infection reported ever having tested for HIV, of whom 14 (50% of the
28) had tested in the previous two years. As unprotected anal
intercourse (UAI) is the most likely route of HIV transmission in these
men, we compared the 18% of self-reported HIV-negative/unknown
serostatus participants who reported UAI with an HIV-positive or unknown
serostatus partner in the previous six months with the 72% who did not
report this behaviour (Table 1). While the prevalence of undiagnosed HIV
infection was higher in the latter group, the difference was not
statistically significant (4.3% vs. 2.0%; p=0.133)
Of the 281 participants who had not tested in the previous two
years, the most common reasons for not testing were a low perceived risk
for HIV infection (31%); wanting to test but not having done it yet
(18%); always practicing safer sex (17%); and a belief they were
HIV-negative (14%) (Table 2). The reported reasons for not testing
differed between those who were HIV-negative by DBS and those with
undiagnosed infection (Table 2). More of those with undiagnosed HIV
infection reported concern about the impact on their relationships (42%
vs. 3.0%; p<0.001); a suspicion that they were already HIV-infected
(33% vs. 1.1%; p<0.001); and not wanting to know (33% vs. 6.3%;
p=0.008). Not having gotten around to getting tested was also a commonly
reported reason, but did not differ significantly between the groups
(33% vs. 17%; p=0.236).
The most commonly reported methods of HIV prevention for men who
self-reported as HIV-negative/unknown and were HIV-negative on DBS
testing were: always having anal sex with condoms (68%); asking their
partner's HIV status before sex (63%); not having their partner
ejaculate inside them (43%); only having unprotected sex with men known
to be HIV-negative (35%); and having insertive anal intercourse only
(34%) (Table 3). We found no differences in reported HIV-prevention
measures used by participants who self-reported as HIV-negative/unknown
and were DBS-negative compared to those with undiagnosed HIV infection.
The use of risk-reduction measures was reported by 91% of study
participants (72% if reporting always having anal sex with condoms was
excluded). When stratified on the basis of serostatus, 86% of
self-reported HIV-positive and 92.1% of self-reported
HIV-negative/unknown serostatus participants reported using at least one
measure to prevent HIV transmission or acquisition.
A total of 78% of participants reported having anal sex in the
previous six months and of these, 59% reported using a condom the last
time they had anal sex. Significantly more self-reported HIV-negative
men reported using condoms the last time they had anal sex than
self-reported HIV-positive men (62% vs. 41%; p<0.001). Overall, 85%
of self-reported HIV-negative men thought it was unlikely or very
unlikely that they would acquire HIV during their lifetime. Among those
with an undiagnosed HIV infection, 10 (50%) of 20 participants thought
that they were very unlikely or unlikely to acquire HIV during their
lifetime.
For men who were HIV-positive by self-report and DBS, the most
commonly reported prevention methods were: asking sex partners'
serostatus (63%) and having sex other than anal sex (58%) (Table 2).
Overall, 37% of HIV-positive men reported having UAI with a partner who
was HIV-negative/unknown serostatus in the previous 6 months.
DISCUSSION
HIV prevalence was 18% overall and increased substantially with age
in this sample of MSM in Vancouver, approaching 1 in 3 for men aged
[greater than or equal to]45 years. Undiagnosed HIV infection accounted
for a small, but potentially important proportion of HIV-positive
individuals in this population. However, it appears that HIV prevention
is a priority for most MSM in this sample, as >90% of participants
reported using at least one HIV risk-reduction measure. The most
commonly reported measure by men who self-reported as
HIV-negative/unknown was always using condoms when having anal sex,
reported by 68% of respondents. This observation contrasts somewhat with
commonly-held views that HIV infection is not a concern for MSM and that
condom use has fallen into disfavour. (5)
These findings have implications for HIV-prevention programs for
MSM in Vancouver. A significant minority of MSM in this survey (36% of
HIV-positive men and 18% of HIV-negative men) reported engaging in UAI
with a serodiscordant or unknown serostatus partner. When combined with
the high HIV prevalence in this sample, this implies a high level of
risk for this minority, although this risk may be mitigated somewhat by
the high levels of HIV treatment reported by the HIV-positive
participants. (6) Indeed, the high HIV prevalence, in part, reflects the
success of antiretroviral therapy in keeping HIV-infected MSM alive,
healthy and available for inclusion in this study. The HIV prevalence we
found is comparable to recent seroprevalence surveys conducted in
Seattle, (7) and other M-Track surveys in Toronto, Ottawa, (8) Montreal
(9) and Victoria. (10)
Second, while close to 70% of HIV-negative men reported always
using condoms as a method of preventing HIV acquisition, when asked
specifically about condom use the last time they had anal sex, this
number fell to 58%. All-partner condom use is a rather crude indicator
of sexual risk-behaviour as MSM may vary their condom use depending on
whether they are having sex with a regular or casual partner and whether
they know the serostatus of their partner. Nevertheless, continued
promotion of condom use and provision of condoms remain fundamental
components of HIV prevention among MSM that should not be neglected.
It also appears that there is opportunity to further promote HIV
testing, especially among MSM <30 years of age, where 25% of
participants reported never having tested for HIV. Knowing that one is
HIV-infected has been shown to increase safer sexual behaviour among
MSM. (11) As 71% of men with undiagnosed infection had tested previously
(with 43% having tested in the previous 2 years), promoting more
frequent HIV testing for MSM could also reduce the number of undiagnosed
HIV infections.
Additionally, facilitating the discussion of HIV serostatus among
MSM would likely improve HIV prevention efforts. Approximately 64% of
participants reported asking the HIV serostatus of sex partners. This
likely facilitates discussion of condom use or other prevention methods
and should be actively promoted. As well, ensuring that disclosure is
frank and not implied, based on subsequent sexual behaviours, should
also be encouraged. (12,13) Additionally, accurate disclosure of HIV
serostatus is only possible if men are truly aware of their serostatus.
In our study, 3% of men who self-reported as HIV-negative were, in fact,
HIV-infected. Hence it is also important to provide MSM with accurate
information regarding the effectiveness of other means of HIV
risk-reduction employed here, including serosorting, strategic
positioning and HIV treatment. While none of these methods are as
effective as 100% condom use, they may contribute to some reductions in
HIV transmission at the community level. (14)
This study has several limitations. First, it is cross-sectional in
nature, so one cannot determine the directions of the associations we
have observed. Second, as we recruited individuals through venues that
cater to gay, bisexual and other MSM, it is only generalizable to those
MSM who frequent these venues. Last, our study is also likely to be
over-represented with individuals who attend these venues frequently,
since they would have a greater probability of being recruited into our
study.
In summary, our study found that 18% of men surveyed in venues or
events that cater to gay, bisexual and other MSM were HIV-infected. This
high prevalence requires that prevention programs do more to promote
primary HIV prevention through a number of different measures, and
support secondary HIV prevention through better identification of
undiagnosed HIV and ensuring effective treatment for those already
infected.
Acknowledgements: The authors thank the venues that participated in
the study, members of the community advisory board, volunteer
interviewers, and the ManCount Study participants. The M-Track/ManCount
Survey was funded by the Public Health Agency of Canada. DMM is
supported by a New Investigator Award from the Canadian Institutes of
Health Research.
Conflict of Interest: None to declare.
Received: April 21, 2011
Accepted: October 16, 2011
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David M. Moore, MDCM, MHSc, [1,2] Steve Kanters, MSc, [1] Warren
Michelow, MSc, [1] Reka Gustafson, MD, MHSc, [4] Robert S. Hogg, PhD,
[1,3] Michael Kwag, BA, [4] Terry Trussler, PhD, [5] Marissa McGuire,
MSc, [7] Wayne Robert, BA, [6] Mark Gilbert, MD, MHSc, [8] and the
ManCount Study Team *
Author Affiliations
[1.] British Columbia Centre for Excellence in HIV/AIDS, Vancouver,
BC
[2.] Faculty of Medicine, University of British Columbia,
Vancouver, BC
[3.] Faculty of Health Sciences, Simon Fraser University, Burnaby,
BC
[4.] Vancouver Coastal Health, Vancouver, BC
[5.] Community-Based Research Centre, Vancouver, BC
[6.] Health Initiative for Men, Vancouver, BC
[7.] Public Health Agency of Canada, Ottawa, ON
[8.] British Columbia Centre for Disease Control, Vancouver, BC
Correspondence: Dr. David M. Moore, BC Centre for Excellence in
HIV/AIDS, St. Paul's Hospital, 610-1081 Burrard Street, Vancouver,
BC V6Z 1Y6, Tel: 604-086-8478, E-mail:
[email protected]
* Members of the ManCount Study Team: Chris P. Archibald, Phillip
Banks, Mark Gilbert, Paul Gustafson, Reka Gustafson, Robert S. Hogg,
Gayatri Jayaraman, Steve Kanters, Michael Kwag, Rick Marchand, Marissa
McGuire, Warren Michelow, David Moore, Susanna Ogunnaike-Cooke, Maureen
Perrin, Wayne Robert, Arn Schilder, Jim Sheasgreen, Meaghan Thumath,
Stephanie Totten, Terry Trussler, Liz Venditti, Tom Wong.
Table 1. Factors Associated With Self-reported Unprotected
Anal Intercourse With a Known HIV-positive or
Unknown Serostatus Partner in the Previous Six
Months by ManCount Study Participants Who
Self-reported as Being HIV-negative or Unknown
Report Risky No Risky P-value
Sex * Sex
N (%) N (%)
Total * 141 (18) 650 (82) --
Median age 31 (25-39) 32 (26-42) 0.202
(interquartile range)
Sexual orientation
Gay/ homosexual 119 (85) 514 (80) 0.459
Bisexual 15 (11) 78 (12) ([dagger])
Straight/ heterosexual 0 (0) 15 (2.5)
Other 6 (4.3) 39 (6.0)
Ethnicity
North American 60 (42) 341 (53) 0.030
Aboriginal 6 (4.3) 18 (2.8) ([dagger])
Asian 5 (3.5) 47 (7.2)
European 42 (30) 156 (24)
Other 28 (20) 87 (13)
Some post-secondary 111 (79) 537 (83) 0.314
education
Personal income >$40,000 68 (50.0) 315 (49.3) 0.881
per year 133 (94.3) 566 (87.9) 0.086
Ever tested for HIV 83 (64.8) 300 (52.8) 0.013
Tested for HIV in last
year
Recruitment site 75 (53.2) 373 (57.4) 0.005
Bar 12 (8.5) 21 (3.2)
Bathhouse 33 (23.4) 163 (25.1)
Event 11 (7.8) 23 (3.5)
Association 10 (7.1) 70 (10.8)
Business
Report unlikely or very 78 (66.7) 484 (89.1) <0.001
unlikely to
acquire HIV infection 6 (4.3) 13 (2.0) 0.133
Unaware of HIV infection
(HIV-positive on DBS)
* Risky sex is defined as self-reported unprotected anal intercourse
with a known HIV-positive or unknown serostatus partner.
([dagger]) Fisher's exact test result.
Note: Totals reflect those who responded to the question asking
whether they were HIV-positive and the variable reported in each row.
As such, the denominators vary somewhat for each variable.
Table 2. Reasons for Not Testing in the Previous 2 Years for 281
Self-reported Serostatus HIV-negative or Unknown Stratified by
DBS HIV Test Result
Reasons for Not DBS HIV-negative DBS HIV-positive P-value
HIV Testing (%) (%) (Fisher's
N = 269 N = 12 Exact test)
I am at low risk 84 (31) 3 (25) 0.760
for HIV infection
I want to be 46 (17) 4 (33) 0.236
tested, I just
haven't done it
yet *
I always have 45 (17) 2 (17) 1.00
safer sex
I think I am 38 (14) 1 (8.3) 1.00
HIV-negative
I did not have 29 (11) 1 (8.3) 1.00
sex with an
infected person
Other reason 27 (10) 1 (8.3) 1.00
I do not want 17 (6.3) 4 (33) 0.008
to know *
I never thought 16 (6.0) 3 (25) 0.039
about it
I am healthy so 15 (5.6) 3 (25) 0.034
I don't need to
be tested
I am afraid of 15 (5.6) 3 (25) 0.034
needles
I could not deal 10 (3.7) 4 (33) 0.002
with knowing I
was infected *
It could affect 8 (3.0) 5 (42) <0.001
my relationships *
I don't have a 9 (3.4) 3 (25) 0.011
doctor
I do not know 9 (3.4) 1 (8.3) 0.358
where to get the
test
I am afraid of 8 (3.0) 2 (17) 0.062
having my name
reported
I am worried 7 (2.6) 3 (25) 0.006
about the impact
on my sex life
I am worried about 7 (2.6) 2 (17) 0.051
being
discriminated
against
It could affect 6 (2.2) 1 (8.3) 0.266
my career or
insurance
I think I am 3 (1.1) 4 (33) <0.001
HIV-positive *
I don't think I 5 (1.9) 1 (8.3) 0.232
can get HIV
If I tested 4 (1.5) 2 (17) 0.023
positive, nothing
can be done
I couldn't get an 3 (1.1) 2 (17) 0.016
appointment for
HIV testing when
I wanted one
Doesn't matter if 2 (0.7) 2 (17) 0.010
I'm infected
because of my age
I don't think the 1 (0.4) 2 (17) 0.005
test is always
right
* Most common responses for undiagnosed HIV infection group.
Table 3. HIV Prevention Strategies Reported by Self-reported
HIV Status and by DBS Result
HIV-negative/
Unknown
Serostatus
(Self-report)
Variable HIV Pos HIV Neg
(Self-report) (DBS)
n/N (%) N (%)
Any HIV prevention measure 149/173 (86) 772/836 (92.3)
Always have anal sex with
condoms N.A. 555/812 (68)
Ask sex partner's HIV
serostatus 105/167 (63) 474/750 (63)
Have sex other than anal sex 95/163 (58) N.A.
No ejaculation inside
partner ([dagger]) 76/160 (48) 319/737 (43)
Serosorting ([double dagger]) 81/161 (50) 263/752 (35)
Strategic positioning
([section]) 59/162 (36) 250/738 (34)
Have unprotected sex only
when viral load is low or
on HIV medication 41/155 (26) 48/719 (6.7)
HIV-negative/
Unknown
Serostatus
(Self-report)
Variable HIV Pos
(DBS)
N (%) p-value
([dagger])
Any HIV prevention measure 22/26 (85) 0.142
Always have anal sex with
condoms 13/24 (54) 0.182
Ask sex partner's HIV
serostatus 14/24 (58) 0.670
Have sex other than anal sex N.A. --
No ejaculation inside
partner ([dagger]) 9/23 (39) 0.832
Serosorting ([double dagger]) 9/23 (39) 0.664
Strategic positioning
([section]) 11/26 (42) 0.403
Have unprotected sex only
when viral load is low or
on HIV medication 3/23 (13) 0.206
* Bivariate comparison of those who are DBS-positive and -negative
among only those who are HIV-negative or unknown by self-report.
([dagger]) Refers to HIV-positive insertive not ejaculating in sex
partner, or HIV-negative or unknown status receptive not allowing sex
partner to ejaculate inside them.
([double dagger]) Refers to not using condoms with a sex partner of
concordant serostatus; i.e., with a known HIV-positive sex partner if
HIV-positive, or with a known HIV-negative sex partner if HIV-negative
or unknown HIV serostatus.
([section]) Refers to only practicing insertive anal sex if one is
HIV-negative and only receptive anal sex if one is HIV-positive.
N.A.--Not asked for individuals self-reporting this HIV serostatus.
Figure 1. HIV prevalence and proportion unaware of HIV-positive
serostatus by age among 1,132 ManCount
Study participants who provided a usable dried
blood specimen
Age Under 30 30-44 45+ P-value
(years) N (%) N (%) N (%)
Aware 16 (3.8) 74 (16) 83 (32) <0.001
([dagger])
Unaware 12 (2.8) 11 (2.4) 5 (1.9) 1.00 ([double
dagger])
Total * 30 (7.1) /422 87 (19) /451 88 (34) /259 <0.001
([section])
* Totals include two positive individuals under 30 and two between 30
and 44 years of age who failed to self-report their HIV serostatus.
([dagger]) p-value for Fisher's exact test to examine the association
between age group and knowledge of HIV seropositivity among those with
a positive HIV test.
([double dagger]) p-value for Fisher's exact test to examine the
association between age group and lack of knowledge of HIV
seropositivity among all study participants.
([section]) p-value for test of trend of HIV prevalence across age
groups.
