Poster presentation at the 8th Annual Conference of the Canadian Association for HIV/AIDS Research in May, 1999, in Victoria, BC. (Previously presented at the 11th Annual BC AIDS Conference, Vancouver, November 1998. Originally presented at the XII International Conference on AIDS, Geneva, Switzerland, July 1998.)

Unsafe Sex and Elevated HIV Incidence among Young Men having Sex with Men (MSM)

Steve Martindale¹; Steffanie A. Strathdee, PhD^1,2; Mary Lou Miller, RN¹; Robert S. Hogg, PhD^1,2; Brian Woodfall, MD³; Phil Sestak, MD³; and Martin T. Schechter, OBC, MD, PhD^1,2

for the Vanguard Project, the University of British Columbia and the British Columbia Centre for Excellence in HIV/AIDS.

1 British Columbia Centre for Excellence in HIV/AIDS, Vancouver.
2 University of British Columbia, Departments of Health Care & Epidemiology, Pathology and Medicine.
3 St. Paul's Hospital, Vancouver.

ACKNOWLEDGEMENTS:

The authors gratefully acknowledge the staff, participants and Community Advisory Board of the Vanguard Project; volunteer recruiter Garry Johnson; participating doctors and HIV testing clinics; and the National Health Research Development Program, Health Canada, for project funding. Artwork by John Ferrie. Poster designed by Steve Martindale, with assistance from Fiona Tetlock.

OBJECTIVE:

To determine HIV incidence among young men having sex with men (MSM) and to investigate trends in condom use.

BACKGROUND:

The Vanguard Project is a prospective study of HIV incidence and risk behaviours which began in May, 1995.

Eligible participants are males between the ages of 18 and 30, living in the Greater Vancouver area, who have not previously tested HIV-positive.

The study is open to all men who have sex with men, regardless of whether they self-identify as gay, bisexual or straight.

Eligible participants who provide informed consent complete an annual self-administered questionnaire and submit a blood sample for HIV antibody testing.

The questionnaire includes information on demographics, sexual behaviour with both men and women and psychosocial scales.

The baseline questionnaire pertains to the one-year period prior to enrolment, whereas the follow-up questionnaire pertains to the period between baseline and follow-up.

METHODS:

Statistical Analysis:

Prevalence of HIV infection and sexual and drug-using behaviours were determined for men who had completed a baseline questionnaire and HIV test as of May, 1998.

Among participants who tested HIV-negative at baseline and returned for follow-up, HIV incidence density and corresponding 95% confidence intervals were calculated.

For the purpose of this analysis, among men reporting always using condoms during anal intercourse prior to baseline, we defined "relapse" as any episode of unprotected anal intercourse reported at follow-up.

HIV-positive men, and men who subsequently became infected with HIV, were excluded from this analysis, since these individuals may have consciously changed their behaviours.

Odds ratios (ORs) for relapse were tested using McNemar's test, and 95% confidence intervals were calculated.

ORs were calculated separately for men who reported having anal sex with regular male partners (> once/month), and casual male partners (< once/month).

RESULTS:

Recruitment:

A total of 681 eligible men had completed a baseline questionnaire and HIV test as of May, 1998.

Participants were recruited through direct outreach (31%), physicians & clinics (29%), friends & other participants (19%), media (12%) and print materials (9%).

Demographics:

Median age was 25 years.

The majority of participants were Caucasian (72%), had completed high school (85%), and were employed (70%).

Sexual behaviours:

With respect to sexual behaviours (Table 1), most participants reported currently having sex only with men (81%), but a sizable proportion (12%) reported having sex with both men and women.

Among men with regular male partners, almost half (49%) reported having at least one episode of unprotected insertive or receptive anal intercourse in the previous year (Table 2).

Among men with casual male partners, 26% of respondents reported having at least one episode of unprotected insertive or receptive anal intercourse in the previous year (Table 2).

HIV Prevalence and Incidence:

At baseline, HIV prevalence was 2.42% [95% CI: 1.86, 2.98].

By May, 1998, a total of 422 men had returned for at least one follow-up visit, for a follow-up rate of 76%.

Eleven men seroconverted between baseline and follow-up, for an HIV incidence rate of 1.72 per 100 person years [95% CI: 0.70, 2.74].

Risk Factors for Seroconversion:

Compared to subjects who remained HIV-negative, HIV seroconverters were more likely to have been paid for sex, to ever have injected drugs, and to report having had unprotected anal sex with a male they knew at the time was HIV-positive (Table 3).

Relapse:

At follow-up, among men with regular partners, the odds of relapse increased two-fold for unprotected insertive and receptive anal intercourse (Table 4).

Among men with casual partners, similar increased odds were observed for unprotected insertive intercourse, but the proportion engaging in unprotected receptive anal intercourse was unchanged (Table 5).

LIMITATIONS:

1. Definitions used may restrict generalizability.
2. Self-reported risk behaviours.
3. Differential follow-up may have caused HIV incidence and behaviour trends to be underestimated.
4. Potential selection bias (e.g. volunteer cohort).

CONCLUSIONS:

Continued high levels of unprotected anal sex observed in our cohort are consistent with an unacceptably high HIV incidence. Seroincidence data reveal the need for prevention programs to take into account male sex workers, MSM/IDUs and men in serodiscordant relationships.

Early follow-up data suggest a disturbing trend towards increasing levels of unprotected anal sex among young gay and bisexual men in Vancouver.

Among other factors, complacency towards HIV infection could reflect undue optimism surrounding recent advances in antiretroviral drug therapy, feelings of fatalism and inevitability, or lack of direct experience of the AIDS epidemic among a newer generation of gay men.

Qualitative studies are needed to examine reasons for engaging in unsafe sex and reasons for relapse. Our data underscore the urgent need for HIV interventions among young gay and bisexual men who remain at high risk for infection.

* restricted to participants who reported having had sexual intercourse with males or females.

Table 2: [back to text]
Self-reported unprotected anal intercourse among young gay/bisexual men at enrolment

REGULAR Partners (n=503)	Unprotected INSERTIVE Anal Sex	Unprotected RECEPTIVE Anal Sex
Without ejaculation	151 (30%)	172 (34%)
With ejaculation	121 (24%)	134 (27%)
At all with a REGULAR partner: 245 (49%)
CASUAL Partners (n=537)	Unprotected INSERTIVE Anal Sex	Unprotected RECEPTIVE Anal Sex
Without ejaculation	85 (16%)	74 (14%)
With ejaculation	51 (9.5%)	31 (5.8%)
At all with a CASUAL partner: 140 (26%)

Table 3: [back to text]
Risk factors for Seroconversion in the Vanguard Project (n=332)

	Non-Converters (n=321)	Converters (n=11)**	p-value
Age (median)	27 yrs (IQR: 24-29)	25 yrs (IQR: 24-27)	0.09Ý
Caucasian	267 (83%)	11 (100%)	0.223*
Employed	292 (94%)	6 (60%)	0.003*
Stable housing	292 (94%)	6 (75%)	0.02*
> or = high school education	287 (90%)	7 (70%)	0.07*
Annual income >$10,000/yr	264 (86%)	5 (56%)	0.03*
Injected drugs	5 (2%)	3 (30%)	<0.001*
Shared needles	1 (0%)	1 (10%)	0.06*
Anal sex with known HIV+ partner	58 (19%)	3 (30%)	0.42*
Unprotected anal sex with known HIV+ partner	11 (3%)	3 (30%)	0.006*
Been paid for sex	23 (7%)	5 (45%)	<0.001*
Ý Wilcoxon rank-sum test. * Fisher's Exact Test. **Data for three participants (2 of whom are now deceased) were obtained from their baseline questionnaires; for one participant, follow-up data are not yet available.

Table 4: [back to text]
Comparison of self-reported episodes of unprotected anal intercourse among 285 young gay/bisexual men with REGULAR partners at baseline vs. follow-up

Unprotected INSERTIVE Anal Sex

Follow-up
Baseline	NO	YES	OR*
NO	144	52	2.2 (CI: 1.3, 3.6)
YES	23	66

Unprotected RECEPTIVE Anal Sex

Follow-up
Baseline	NO	YES	OR*
NO	130	55	1.9 (CI: 1.2, 2.9)
YES	29	71

*based on McNemar's statistics.
NB: Tables for REGULAR and CASUAL partners are not mutually exclusive.

Table 5: [back to text]
Comparison of self-reported episodes of unprotected anal intercourse among 278 young gay/bisexual men with CASUAL partners at baseline vs. follow-up

 Unprotected INSERTIVE Anal Sex

Follow-up
Baseline	NO	YES	OR*
NO	189	43	1.7 (CI: 1.1, 2.8)
YES	25	21

 Unprotected RECEPTIVE Anal Sex

Follow-up
Baseline	NO	YES	OR*
NO	216	26	1.3 (CI: 0.7, 2.3)
YES	20	16

 *based on McNemar's statistics.
NB: Tables for REGULAR and CASUAL partners are not mutually exclusive.