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

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)

39

28 11

27 1

Background

HIV ‘Treatment as Prevention’: HPTN 052

(Cohen et al., 2011, NEJM)

Background

HIV ‘Treatment as Prevention’: PARTNER

(Rodger et al., 2014, CROI)

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.

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.

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

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.

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?

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

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%

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%

Results

Antiretroviral therapy and viral load

• At baseline, 89.5% of HIV-positive partners were taking ART.

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

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

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.

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

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

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

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

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’

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

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

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)

Results

Across follow-up: Perceived viral load & ‘Any CLS’

Undetectable Detectable/Unknown0

10

20

30

40

50

60

70

80

Any CLSInsertiveReceptive

Perceived Viral Load

Pe

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nta

ge

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.

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.

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