Sexual Behaviour with other HIV-Positive Men is a Key Driver of New
Diagnoses with Syphilis, Gonorrhoea and Chlamydia among MSM
Attending HIV care in Ontario, Canada
Ann N Burchell1,2, Vanessa G Allen3, Sandra Gardner1,2,
Darrell Tan4,5, Ramandip Grewal1, Veronika Moravan1,
Janet Raboud2,5, Ahmed M Bayoumi2,4, Rupert Kaul2,5,
Tony Mazzulli3, Frank McGee6, Sean B Rourke 1,2,4
1. Ontario HIV Treatment Network, Toronto, Canada, 2. University of Toronto, Toronto,
Canada,3. Public Health Laboratories, Public Health Ontario, 4. St. Michael’s Hospital, Toronto,
Canada, 5. University Health Network, Toronto, Canada, 6. AIDS Bureau, Ontario Ministry of
Health and Long Term Care, Toronto, Canada
Presenting Author: Ann Burchell <[email protected]>
Ongoing and sustained epidemics of bacterial STIs among gay and other men who have sex with men (MSM) have been noted in many urban settings
internationally, commonly among men co-infected with HIV. We identified sexual risk factors for a new diagnosis of syphilis, chlamydia or gonorrhoea
among MSM participating in an HIV clinical cohort in Ontario, Canada.
Methods
We analyzed data from MSM participants who were followed from 2010
to 2013 and who self-completed ≥1 questionnaire that measured sexual
activity during the preceding 3 months.
A new diagnosis of syphilis, chlamydia or gonorrhea was ascertained via
record linkage with the Public Health Ontario Laboratories.
We conducted separate Cox regression analyses for time from baseline
questionnaire to a new diagnosis of (1) syphilis and (2) chlamydia or
gonorrhea. Multivariable models included age, race, and region as
measured at baseline and time-updated measures of sexual behaviour
and viral load.
OHTN Cohort Study (OCS) Profile
The OCS is an anonymous, multi-site, open dynamic cohort
of people attending specialty HIV clinics in Ontario, Canada.
Primary data collection includes medical chart abstractions
and annual interviews. We also conduct record linkage with
external administrative health databases including the Public
Health Ontario Laboratories. From 01/1995 to 03/2014, a
total of 6,408 participants were enrolled and followed over
38,388 person-years. Average annual attrition is 3.8 per 100
person-years. As of 03/2014, 58% (3,709) were still under
active follow-up.
Table 1. Characteristics of HIV-positive men
who have sex with men at first completion
of sexual behaviour questionnaire
Age
Mean (SD)
Sexual orientation
Gay
Bisexual
Heterosexual
Unknown
Race/ethnicity
White
Black/African
Mixed race/ethnicity
Indigenous
Other
Education
High school or less
Some post-secondary
Completed post-secondary
Year of HIV diagnosis
Median (IQR)
HIV clinical status
Initiated antiretroviral treatment
Mean CD4 cell count/mm3 (SD)
Undetectable viral load (<40 copies/mL)
Number of sexual partners past 3 months
None
One
Two to four
Five or more
Anal sex behaviours past 3 months
Not sexually active
Sexually active but no anal sex
Anal sex always with a condom
Some condomless anal sex
Table 2. Sexual risk factors for a new
diagnosis with a bacterial STI among HIVpositive men who have sex with men
Sexual behaviours in
preceding 3 months
Number of HIV-positive partners
None
One
Two to four
Five or more
Number of HIV-negative/status
unknown partners
None
One
Two to four
Five or more
Anal sex with HIV-positive
partners
N
o sexual activity with HIVpositive partner
Sexually active but no anal sex
Anal sex always with a condom
Any condomless anal sex
Anal sex with HIV-negative/status
unknown partners
N
o sexual activity with HIVnegative/status unknown partner
Sexually active but no anal sex
Anal sex always with a condom
Any condomless anal sex
Syphilis
Cumulative
Adjusted
incidence @ 24 hazard ratio
months (95%CI)
(95%CI)
Chlamydia/Gonorrhea
Cumulative
Adjusted
incidence @ hazard ratio
24 months
(95%CI)
(95%CI)
3.7 ( 2.6 , 4.8)
1.6 (0.9, 2.2)
Reference
Reference
8.8 (5.7 , 11.7)
2.9 (1.1, 4.6)
14.7 (10.1 , 19.1) 1.3 (0.8, 2.2) 6.0 (3.0, 9.0) 1.9 (0.8, 4.1)
38.2 (28.1 , 47.0) 3.6 (2.1, 6.3) 10.6 (4.6, 16.6) 4.0 (1.7, 9.5)
2.6 (1.8 , 3.4)
2.9 (1.6 , 4.1)
5.8 (3.5 , 8.0)
9.4 (6.2 , 12.4)
3.7 (2.6 , 4.8 )
Reference
1.3 (0.7, 2.3)
1.1 (0.6, 2.0)
Reference
5.6 (1.5 , 9.6 ) 1.1 (0.5, 2.7)
11.1 (5.9 , 16.1) 2.1 (1.1, 4.0)
19.6 (15.6 , 23.5) 2.5 (1.5, 4.0)
5.6 (4.2 , 6.9)
Reference
5.3 (2.2 , 8.3)
0.8 (0.4, 1.6)
10.0 (6.7 , 13.1) 1.1 (0.6, 1.9)
16.9 (12.2 , 21.5) 1.2 (0.6, 2.1)
1.9 (1.1, 2.8)
1.6 (0.3, 2.9)
4.8 (2.0, 7.7)
6.4 (3.1, 9.7)
1.6 (0.9, 2.2)
0.9 (0.0, 2.5)
3.3 (0.4, 6.2)
7.3 (4.8, 9.8)
1.9 (1.1, 2.8)
0.4 (0.0, 1.3)
5.3 (2.9, 7.6)
4.6 (2.1, 7.2)
Reference
1.2 (0.5, 2.9)
1.2 (0.5, 2.9)
Reference
0.9 (0.2, 4.2)
2.3 (0.9, 6.0)
2.2 (1.0, 5.1)
Reference
0.7 (0.2, 2.2)
1.4 (0.6, 3.3)
1.2 (0.5, 3.0)
Figure 1. Cumulative incidence of a new
bacterial STI diagnoses, by number of HIVpositive partners
47.3 (10.6)
88%
7%
3%
1%
New Syphilis Diagnoses by Number of
HIV-Positive Partners
New Chlamydia/Gonorrhea Diagnoses
by Number of HIV-Positive Partners
74%
4%
8%
6%
8%
23%
22%
55%
1998 (1991-2005)
91%
538 (254)
78%
40%
24%
23%
13%
40%
12%
19%
29%
Results
At baseline, men were on average 47 years old and the majority were
White, on antiretroviral treatment, and had undetectable viral load (Table
1).
There were 165 syphilis, 41 chlamydia and 46 gonorrhea diagnosis events
at follow-up. Cumulative incidence proportions at 24 months were
8.0% (95%CI 6.8%, 9.3%) for syphilis and 2.8% (95%CI 2.1%, 3.6%) for
chlamydia/gonorrhea.
Sexual behaviour risk factors for a new bacterial STI diagnosis are shown
in Table 2.
Cumulative incidence was estimated treating the number of HIV-positive partners in the past
three months as a time-dependent covariate.
Conclusions
Among all behaviours evaluated, report of multiple HIV+ partners was
most predictive of a new bacterial STI diagnosis. Sexual behaviour with
HIV-negative/status unknown partners did not independently influence
STI diagnosis risk.
Bacterial STIs have reached high prevalence in certain sexual networks of
HIV+ MSM engaging in sex with other positive men. Our findings suggest
these may have low connectedness with sexual networks among HIVnegative MSM.
STI control strategies for MSM must specifically address prevention
needs for HIV-positive men.
Many thanks to: volunteer participants; past and present members of the OCS
Governance Committee (Past: Darien Taylor, Dr. Evan Collins, Dr. Greg Robinson, Shari
Margolese, Tony Di Pede, Rick Kennedy, Michael Hamilton, Ken King, Brian Finch, Dr.
Ahmed Bayoumi, Dr. Clemon George, Dr. Curtis Cooper, Dr. Troy Grennan, and present:
Patrick Cupido (Chair), Anita Benoit, Breklyn Bertozzi, Adrian Betts, Les Bowman, Lisungu
Chieza, Tracey Conway, Brian Huskins, Claire Kendall, Nathan Lachowsky, Joanne Lindsay,
John MacTavish, Mark McCallum, Colleen Price, Lori Stoltz, Rosie Thein); interviewers,
data collectors, research associates and coordinators, nurses, physicians, and OHTN staff
who provide support for data collection and management. We also acknowledge the Public
Health Ontario Laboratories for supporting record linkage.
The highest cumulative incidence was observed among men reporting
≥ 5 HIV+ partners (Figure 1). Population attributable fractions for this
risk factor were 32% and 23% for syphilis and chlamydia/gonorrhea,
respectively, despite overall low prevalence of this behaviour (5.3% at
baseline).
Funding: Canadian Institutes of Health Research (CIHR) operating grant 111146, a CIHR
New Investigator award to ANB, and OHTN Chair and Toronto and Western Hospital
Foundation Skate the Dream Fund award to JR. The OCS is funded by the AIDS Bureau,
Ontario Ministry of Health and Long-Term Care.
OHTN