Download - Background
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Evidence of behavioural risk compensation in a cohort study of HIV
treatment and transmission in homosexual male serodiscordant couples
Benjamin R Bavinton, Fengyi Jin, Iryna Zablotska, Garrett Prestage, and Andrew E Grulich, for the Opposites Attract Study Group
20th International AIDS Conference (AIDS 2014)
23 July 2014
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Total seroconversions
Linked infections Unlinked infections
Delayed ART Early ART
Total N = 1,763 couples
96% reduction in HIV transmission risk
(HR=0.04, 95%CI=0.01-0.27, p<0.001)
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28 11
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Background
HIV ‘Treatment as Prevention’: HPTN 052
(Cohen et al., 2011, NEJM)
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Background
HIV ‘Treatment as Prevention’: PARTNER
(Rodger et al., 2014, CROI)
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Background
Behavioural risk compensation
• Behavioural risk compensation: Reduction in condom use due to perceived protection from antiretroviral medications.
• Behavioural risk compensation has not been evident in clinical studies of antiretroviral-based HIV prevention.
• Condom use typically increases in such studies.
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Method
Study Design
• Prospective longitudinal cohort study.
• Open enrolment (currently funded until December 2015).
• Unit of recruitment is a couple comprising two men in an ongoing sexual relationship where one is HIV-positive and the other HIV-negative at baseline.
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Method: Study Sites
Rio de Janeiro Instituto de Pesquisa Clinica
Evandro Chagas (IPEC)
BangkokThai Red Cross AIDS Research Centre
CairnsCairns Sexual Health Centre
Brisbane Gladstone Road
Medical Centre
SydneyDr Doong’s SurgeryEast Sydney DoctorsHoldsworth HouseSt Vincent’s Hospital (IBAC)Sydney Sexual Health CentreTaylor Square Private Clinic
MelbourneAlfred Hospital
Centre ClinicMelbourne Sexual Health Centre
Northside ClinicPrahran Market Clinic
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Method
Study Design
• Couples attend at least 2 clinic visits per year:– Viral load and CD4 in HIV-positive partners– HIV antibody tests in HIV-negative partners
• Both partners complete an online questionnaire at each clinic visit.
• Phylogenetic analysis to be conducted at the end of the study.
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Method
Research Question
• Is there evidence of behavioural risk compensation in the Opposites Attract cohort?
– Do the HIV-negative partners report more condomless anal sex with their HIV-positive study partner when they perceive their partner to have undetectable viral load?
– Are these patterns sustained over time?
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Results
Enrolments, visits and couple-years
• 124 couples enrolled in Australian clinical sites, and 108 (87.1%) had attended at least one follow-up visit.
• Number of visits: – Mean: 2.93 visits (SD = 2.03)– Median: 2 visits (range = 1 – 14)
• Mean time between visits: 105 days (Median: 90 days)
• This analysis includes 129.3 couple-years of follow-up time.
1 2 3 4 5 6 7 8 9 10 11 12 13 140
20
40
60
80
100
120
140
Study Visit
Nu
mb
er
of
co
up
les
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Results
Demographics at baseline
HIV-Negative
PartnerHIV-Positive
Partner
Age – mean (median) 39.8 (38.7) 40.5 (39.3)
‘Gay’ sexual identity 97.5% 98.4%
Ethnicity
Anglo-Australian 60.5% 53.7%
Other Caucasian 12.9% 15.5%
University education 52.8% 47.2%
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Results
Relationship characteristics at baseline
• Length of relationship: • 69.1% of couples lived together.
• 96.0% described each other as ‘partner’, ‘husband’ or ‘boyfriend’.
• 48.8% of HIV-negative partners had sex with other partners outside the couple.
12 months or less:
33%
1 to 5 years:
33%
5 or more years:
34%
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Results
Antiretroviral therapy and viral load
• At baseline, 89.5% of HIV-positive partners were taking ART.
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Results
Antiretroviral therapy and viral load
• At baseline, 89.5% of HIV-positive partners were taking ART.
• Viral load pathology results:
Undetectable Detectable0
102030405060708090
100
Pe
rce
nta
ge 75.8
24.2
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Results
Antiretroviral therapy and viral load
• At baseline, 89.5% of HIV-positive partners were taking ART.
• Viral load pathology results:
<400 copies >400 copies0
102030405060708090
100
Pe
rce
nta
ge
Undetectable Detectable0
102030405060708090
100
Pe
rce
nta
ge 75.8
24.2
90.0
10.0
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Results
Perceived viral load
• 77.4% of HIV-negative partners perceived their HIV-positive partner’s viral load to be undetectable.
• Perceptions were mostly in accord with pathology results.
• Detectable viral load was overestimated rather than underestimated:
– Of the 94 men who perceived the viral load to be undetectable, 2.2% of the partners actually had over 400 copies.
– Of the 21 men who perceived the viral load to be detectable, 61.9% of the partners actually had less than 400 copies.
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Insertive Receptive withdrawal
Receptive ejaculation
0
10
20
30
40
50
60
70
HIV-negative partners reporting CLS with study partner by CLS type
Pe
rce
nta
ge
Results
Condomless sex (CLS) within the couple
• At baseline, total of 66.1% of HIV-negative partners reported ‘any CLS’ with hisHIV-positive partner in the previous 3 months.
• These proportions were similar during follow-up.
58.9
37.9
18.6
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Results
Sex within couples: Total acts of anal sex
• Text Total
number% of acts
Mean (SD) Median Range
Anal sex acts 9,342 100.0 75.34 (109.6) 35 0 – 650
Condomless anal sex acts 6,425 68.78 51.81 (101.2) 13 0 – 650
Insertive 3,867 60.19 31.19 (68.9) 5 0 – 541
Receptive – withdrawal 1,258 19.58 10.15 (24.1) 0 0 – 179
Receptive – ejaculation 1,300 20.23 10.48 (31.8) 0 0 – 220
Anal sex acts with condoms 2,917 31.22 23.52 (47.8) 8 0 – 367
Insertive 1,712 58.69 13.81 (28.6) 4 0 – 184
Receptive 1,205 41.31 9.72 (24.5) 0 0 – 184
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Results
Sex within couples: Total acts of anal sex
• Text Total
number% of acts
Mean (SD) Median Range
Anal sex acts 9,342 100.0 75.34 (109.6) 35 0 – 650
Condomless anal sex acts 6,425 68.78 51.81 (101.2) 13 0 – 650
Insertive 3,867 60.19 31.19 (68.9) 5 0 – 541
Receptive – withdrawal 1,258 19.58 10.15 (24.1) 0 0 – 179
Receptive – ejaculation 1,300 20.23 10.48 (31.8) 0 0 – 220
Anal sex acts with condoms 2,917 31.22 23.52 (47.8) 8 0 – 367
Insertive 1,712 58.69 13.81 (28.6) 4 0 – 184
Receptive 1,205 41.31 9.72 (24.5) 0 0 – 184
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Results
Sex within couples: Total acts of anal sex
• Text Total
number% of acts
Mean (SD) Median Range
Anal sex acts 9,342 100.0 75.34 (109.6) 35 0 – 650
Condomless anal sex acts 6,425 68.78 51.81 (101.2) 13 0 – 650
Insertive 3,867 60.19 31.19 (68.9) 5 0 – 541
Receptive – withdrawal 1,258 19.58 10.15 (24.1) 0 0 – 179
Receptive – ejaculation 1,300 20.23 10.48 (31.8) 0 0 – 220
Anal sex acts with condoms 2,917 31.22 23.52 (47.8) 8 0 – 367
Insertive 1,712 58.69 13.81 (28.6) 4 0 – 184
Receptive 1,205 41.31 9.72 (24.5) 0 0 – 184
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Results
Primary Analysis
• What is the association between condomless anal sex and perceived viral load?
– Baseline analysis: ‘Any condomless sex’
– Baseline analysis: Number of acts of condomless sex
– Longitudinal analysis: ‘Any condomless sex’
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Undetectable Detectable/Unknown
0
20
40
60
80
Perceived Viral Load
Per
cen
tag
e
Results
Baseline: Perceived viral load and ‘Any CLS’
• At baseline, HIV-negative partners were more likely to report CLS with their study partner when the perceived VL was undetectable.
OR = 3.5995% CI = 1.49-8.63p-value = 0.004
72.9
42.9
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Results
Baseline: Perceived viral load and acts of CLS
Perceived Undetectable VL
Perceived Detectable or Unknown VL
Median Mean Median Mean
Any condomless sex 8 18.4 0 10.8 *
Insertive condomless sex 4 11.6 0 4.7 *
Receptive condomless sex 0 6.8 0 6.1
* Wilcoxon Ranksum Test: p < 0.01
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Results
Across follow-up: Perceived viral load and ‘Any CLS’
Percentage having UAI IRR 95% CI p-value
Perceived UVL
PerceivedDVL/DK
Any CLS 74.3 35.2 1.98 1.27-3.07 0.002
Any Insertive CLS 64.4 29.5 2.04 1.27-3.28 0.003
Any Receptive CLS 49.0 25.0 1.83 1.02-3.32 0.044
Statistical Test Used: Generalised Linear Models (Poisson regression)
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Results
Across follow-up: Perceived viral load & ‘Any CLS’
Undetectable Detectable/Unknown0
10
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30
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80
Any CLSInsertiveReceptive
Perceived Viral Load
Pe
rce
nta
ge
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Conclusion
• Condomless anal sex (CLS) within these homosexual serodiscordant couples is common, and higher than found in other samples of gay men.
• CLS is strongly associated with the HIV-negative partner’s perception of his HIV-positive partner’s viral load.
• There is evidence of behavioural risk compensation in this cohort, and this pattern of behaviour continues over time.
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Conclusion
• There may be more evidence for risk compensation relating to HIV-negative partners taking the insertive role in condomless anal sex.
• The Opposites Attract Study continues to recruit, and will continue follow-up for a further 18 months.
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Acknowledgements
All Study Participants
Study Investigators: Andrew Grulich, Garrett Prestage, Iryna Zablotska, Fengyi Jin, David A Cooper, Anthony Kelleher, David Wilson, Kersten Koelsch, Christopher Fairley, Kathy Triffitt, Sean Emery, Beatriz Grinsztejn, Nittaya Phanuphak, Benjamin Bavinton
Research Assistant: Lara Cassar
Site Investigators: David Baker, Mark Bloch, Nicolas Doong, Jennifer Hoy, Anna McNulty, Richard Moore, David Orth, Catherine Pell, Norm Roth, Darren Russell, Ban Kiem Tee, David Templeton
All Recruiting Clinicians
Laboratory Partners: Kate Merlin, Doris Chibo, Bertha Fsadni, Shayla Sharmin, Brooke Berry, Sandro Nazer, Tippawan Pankam
Site Coordinators/Staff: Colette Cashman, Jess Costa, Sian Edwards, Ruth Khalili Friedman, Shruti Gupta, Peta Hamill, Shane Hewitt, Julia Hoffman, Piranun Hongchookiat, Vicki Ieroklis, Helen Kent, Helen Lau, Karen McRae, Siriporn Nonenoy, Elizabeth Odgers, Janine Roney, Egydio Sampaio, Nicky Sharp, Julie Silvers, Kate Sinn, Rachel Woolstencroft, David Youds
Community Partners: ACON, VAC, Positive Life NSW, Living Positive Victoria, HIV/AIDS Legal Centre
Designers: Danny Adams, James Sheraton
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