Trends in HIV incidence and sexual behaviour among a cohort of men who have sex with men (MSM) in Montreal: 1996-2002 Robert S. Remis, Michel Alary, Joanne Otis, Benoit Mâsse, Eric Demers, Clemon George, Jean Vincelette, Bruno Turmel, René Lavoie, Roger LeClerc, Raymond Parent and the Omega Study Group XIV International Conference on AIDS Barcelona, Spain, July 9, 2002

Background MSM in Montreal seriously affected by the HIV epidemic Omega is a cohort study of 2,000 seronegative gay men whom we are following to better understand HIV transmission in Montreal First subject recruited October 1996

Study objectives Estimate HIV incidence and identify risk factors associated with seroconversion among Montreal MSM Monitor and characterize trends in sexual behaviour Facilitate transfer of knowledge to community groups for HIV prevention

Recruitment and follow-up MSM HIV-negative or unknown serostatus Recruited from community and clinical sites Follow-up visit every 6 months Continuous recruitment to replace those lost to follow-up Attempt to oversample younger (<30 years) and marginalized MSM and those from ethnic minorities

Data and specimen collection Self-administered and interviewer administered questionnaires on: Demographic characteristics Sexual behaviours, lifetime and previous 6 months Psychosocial data HIV and syphilis test at each visit

Statistical analysis, trends in sexual behaviour Calendar time divided into six-month periods Each subject presenting at a particular calendar visit included Trend analysis: General estimating equation (GEE) to control for multiple visits by the same subject

Characteristics of participants (n=1,787) Age Median 31, 80% 21 – 47 Education College/university 69% Residence Montreal Island 88% Place of Birth Quebec 71%, Canada other 12% Language French only 79%, English only 12%

HIV prevalence at baseline by age

HIV prevalence at baseline by education p-value Education < Secondary Secondary/College Higher 112 700 699 7.4% 1.4% 0.86% 0.001

HIV prevalence at baseline by drug injection

HIV prevalence at baseline by sexual history p-value Age at first homosexual sex <15 15-20 20+ 395 486 316 3.3% 1.2% 0.00% 0.002   Number of casual partners, lifetime 0-5 6-49 50+ 379 710 585 0.79% 1.3% 2.8% 0.03

Incidence density among subjects with two or more visits (n=1,436) Age Sero- conversions Person-years Incidence density (95% CI) <30 30+ 11 12 1,493 2,549 0.74 (0.37, 1.3) 0.47 (0.20, 0.74) Total 23 4,041 0.57 (0.34, 0.80)

HIV incidence by age group and period of study

Unprotected anal sex among subjects by sexual partner type and calendar time 04-09/97 10/98-03/99 04-09/00 10/01- 03/02 p-value p-value, adjusted Relationship % Casual partner 8.2 10.4 11.1 11.5 0.02 NS Regular HIV- 21.4 23.0 23.2 24.2 0.09 All except regular HIV- 15.7 16.6 18.9 19.4 0.005 Regular HIV+ 0.6 1.3 1.4 1.0 Regular HIV? 8.8 7.7 9.0 9.8 0.004 Any partner 34.1 36.4 37.5 40.9 0.0003

Unprotected anal sex among subjects <30 years by sexual partner type and calendar time 04-09/97 10/98-03/99 04-09/00 10/01- 03/02 p-value p-value, adjusted Relationship % Casual partner 4.4 12.0 10.1 13.4 0.01 NS Regular HIV- 22.1 23.7 27.3 32.3 0.08 All except regular HIV- 18.8 20.3 21.2 23.4 0.06 Regular HIV+ 0.9 0.4 1.1 0.5 Regular HIV? 15.2 11.0 13.0 12.9 Any partner 36.7 40.9 43.9 52.0 0.006

Unprotected anal sex among subjects 30+ years by sexual partner type and calendar time 04-09/97 10/98-03/99 04-09/00 10/01- 03/02 p-value p-value, adjusted Relationship % Casual Partner 10.0 9.3 11.6 10.8 NS Regular HIV- 21.0 22.5 21.2 20.9 All except regular HIV- 14.4 14.0 17.8 0.02 Regular HIV+ 0.4 1.9 1.6 1.2 Regular HIV? 5.9 5.3 7.0 8.7 0.09 0.01 Any partner 32.9 33.2 34.4 36.5 0.002

Limitations Data on behaviours self-reported Subjects not necessarily representative of MSM in Montreal Selective attrition may introduce bias

Conclusions HIV prevalence at baseline related to age, drug injection and age at first homosexual sex Trends in HIV incidence differ in younger versus older MSM Overall, HIV incidence relatively low and stable Reasons are not clear; organization dedicated to HIV prevention in MSM may in part be responsible Increase in 2001-02 may be real, given increasing risky sexual behaviour

Acknowledgements Gay and HIV-related community organizations Staff, volunteers and Steering Committee members Funding agencies who supported the study: Canadian Institutes for Health Research Centre québécois de coordination du sida Fonds de la recherche en santé du Québec Men who contributed their time and energy by participating in the study